PRELIMINARY PUBLIC HEALTH ASSESSMENT
BIG RIVER MINE TAILINGS DESLOGE
(a/k/a ST. JOE MINERALS)
DESLOGE, ST. FRANCOIS COUNTY, MISSOURI
|Year of Sample||Lead||Cadmium||Zinc||Cobalt||Nickel||Arsenic|
| 1980 |
| 826 - 6,200 |
| 6.8 - 78.6 |
| 233 - 3,990 |
| 1988 |
|880 - 1,440||8.4 - 19||370 - 1,100||9.8 - 18||6.9 - 17||ND|
| 1990 |
| 910 - 13,000 |
Surface & Subsurface
| 8.4 - 79 |
| 370 - 4,300 |
| ND - 42 |
| ND - 37 |
| ND - 14 |
|1992||25 - 5,360||-||-||NA||NA||-|
|Background||64 - 76||ND||35 - 67||12 - 16||ND||6.2 - 9.5|
| Comparison |
value & reference
|-|| 1 EMEG |
| 600 RMEG |
|ppm = parts per million||ND = Not Detected||- = Not available||NA = Not Analyzed|
| 1991 |
| T |
| ND |
| ND - 7.9 |
| 13.7 - 16.7 |
ND - 12.8
| 16.6 - 617 |
ND - 28.9
| ND - 46.5 |
ND - 32.9
| 60.2 - 705 |
69.4 - 416
| 1990 |
| T |
| 25 - 110 |
ND - 37
| ND - 37 |
ND - 27
| ND - 350 |
ND - 360
| 23 - 9,300 |
ND - 60
| ND - 680 |
ND - 620
| 26 - 850 |
ND - 23,000
| 1990 |
| T |
| ND - 21 |
| ND - 190 |
| ND - 85 |
| 36 - 14,000 |
20 - 33
| ND - 92 |
ND - 60
| 98 - 9,100 |
27 - 1,900
|14 - 85 |
ND - 51
|ND - 30 |
|53 - 170 |
ND - 55
|1,700 - 10,000 |
ND - 74
|60 - 170 |
ND - 43
|470 - 2,500 |
ND - 450
|7 EMEG |
EPA Action Level*
|ppb = parts per billion||ND = Not Detected||T - Total||D = Dissolved||- = Not Available|
|* = Applies to drinking water sample only|
| National Pile |
|1640 - 9283 |
|2 - 87 |
|81 - 5,055 |
|51 - 628 |
|Elvins Pile |
|851 - 11,600 |
|19.8 - 202 |
|108 - 11,900 |
|Leadwood Pile |
|597 - 17,000 |
|9.3 - 1,870 |
|633 - 25,800 |
|Bonne Terre Pile |
|1,300 - 7,000 |
|3 - 29.5 |
|51.3 - 967 |
|Federal Pile |
|580 - 2,830||-||-||-|
|Comparison value |
|-||1 EMEG |
|600 RMEG |
|On-Site Levels for comparison (Big River Mine Tailings/St. Joe Minerals. Desloge) ||25 - 13,000||6.8 - 79||35 - 4,300||-|
|ppm = parts per million||- = Not Available|
|all levels in ppm|
(with a single sample at 220)
(with a single sample at 27,460)
(with a single sample at 3,550)
|< = less than||ppm = parts per million||ND = non-detect|
|NOTE: No ATSDR comparison values are available for metals in indoor dust. An estimate of exposure cannot be determined from the available data, nor can it be determined whether a health threat exists. Data is presented for information only.|
|D = Dissolved||T = Total||ND = Not Detected||ppm = parts per million||ppb = parts per billion|
|Source: EPA 1991||L = Low||M = Medium||H = High|
|Total||levels in ppb|
|Big River |
|ND||ND||ND - 74||ND|
|Big River above |
|Big River along |
|28 - 34||ND - 4.8||74 - 120||41 - 100|
|Flat River |
|Big River |
approx. 5 miles
below site &
2.5 miles below
|Turkey Creek |
drains part of
|Big River 15 |
|ppb = parts per billion||ND = Not Detected|
|J = Data reported but not valid by approved QA/QC procedures|
|Big River |
|ND||ND - 1.4||21J - 53J|
|Leadwood tailings |
|Big River |
|Big River along |
Desloge Tailings pile
|21 - 120||1,300 - 3,600||840J - 6,700|
|Flat River tributary |
that drains Federal
|Big River approx. 5 |
miles below site &
2.5 miles below Flat
|Turkey Creek. |
drains part of Bonne
|Big River 15 miles |
|ppm = parts per million |
J = Data reported but not valid by approved QA/QC procedures
ND = Not Detected
|Location||Crayfish||Mollusks (mean)||Fish (mean)|
|- = Not Available||ppm = parts per million||* Single 25 year old catfish|
|Exposure Pathway Elements||Type of |
|Point of |
|Route of |
of the area
|Indoor Dust||Tailings |
Air & Dust
of the area
of the area
Appendix C: Comments and Responses on the Draft for Public Comment of
Preliminary Public Health Assessment for Big River Mine Tailings/St. Joe Minerals
Comments and Responses on the Draft for Public Comment for the Preliminary
Public Health Assessment for Big River Mine Tailings/St. Joe Minerals
- The document is not easy to read. Conjecture is mixed with fact, leading to the unintentional incorporation of "scare factors" in the report.
We do try to write the public health assessments in a readable way. When dealing withtechnical information, we often fall short of that goal. Thank you for telling us that youhad trouble understanding the document. We will make ATSDR aware of this and willencourage development of a format that is more understandable.
We are not sure what you consider "scare factors." The information provided is accurateand is current as to our knowledge of toxicology today. Our intent is to inform people ofhow they are exposed to contaminants with the hope that they will take precautions toreduce their exposure.
- It is very important to consider the species of metal-bearing minerals and how readily metals are released into the environment.
Mineral speciation is important to assessing what impact the Big River Mine Tailings site ishaving on local residents' health. However, recent studies conducted by EPA Region VIIIshow there may be many different lead species found in mine tailings, and that probably alllead species can be absorbed by the human body (bioavailable) to some degree. While itmay be less bioavailable than other lead species, galena still can enter and affect the humanbody. We currently are in the process of doing an exposure study on blood-lead levels inchildren to determine the bioavailability of the tailings in the area. We also understandthat EPA may have plans to conduct speciation testing along with environmental testing forthe blood-lead study.
- Speciation should have been evaluated during the assessment and before the report waswritten.
One of the purposes of the public health assessment is to identify data gaps and to makerecommendations to fill that gap. The recommendation is made in this document toperform speciation; however, recent studies by EPA indicate that all forms of lead are, tosome degree, bioavailable. Realistically, when deciding on how to remediate contaminationsuch as that of the mine tailings in the area, EPA will be evaluating many options. One ofthose options may be to convert the lead to the least bioavailable form. That action,coupled with the on-going community education activities that are underway, may pose thebest solution for this problem. We are working closely with EPA to evaluate the feasibilityof phosphate treatment as a method of addressing widespread metal contamination incombination with community health education.
- If lead is so toxic, why don't we see Suckers and other bottom fish dead and floating in the Big River?
While lead has been well-proven as a toxin, both to humans and to animals, exposuresusually do not cause immediate (acute) affects such as death except at extremely high doses. Effects are long-term (chronic) because lead accumulates in the body, and effectsare not usually physically obvious. Lead exposure can have very serious effects on humansand animals.
- In regard to Recommendation 3, I think resources could be better used for other studies, suchas the lung cancer study, water sampling, etc. Exposure to large amounts of lead sulfide does notelevate blood-lead levels. Why spend money on this aspect when we know lead sulfide does notcontribute lead to the bloodstream?
Contrary to current belief, lead sulfide is bioavailable and is a health threat. It is true thatthis species of lead is not as toxic as others and takes more to produce health effects, butrecent research shows that lead sulfide does enter and can harm the body. Our mandate isto protect public health, and we feel this study will contribute information that we need toadvise affected people and yet unaffected people in the area.
- Also, is a sucker with 1 ppm lead a health risk if some fruits and vegetables have several ppm lead? Is the fish advisory really necessary?
Our goal is to reduce lead exposure to the extent possible. The fish advisory is one of theways we can alert people and, hopefully, reduce exposure to lead by eliminatingconsumption of contaminated fish.
- I was born and raised in the Old Lead Belt and moved to the New Lead Belt in 1973. I haveconstantly been exposed to wind-blown tailings and water "contaminated" by the heavy metals,both as a result of the mining activity and by the naturally occurring mineralization. I have beenemployed by a mining company for more than 25 years and have worked in the mines and millsof the Old and New Lead belts. Because of this constant exposure, I should have a much higherblood-lead level than the average citizen of the Old Lead Belt. But my most recent blood testshowed less than 5 micrograms per deciliter of blood, measured in December 1993.
The blood-lead level is only a snapshot of a person's lead exposure. Lead does not stay inthe bloodstream for very long, especially in adults. The lead leaves the blood and is storedin bone, so a blood test only shows lead levels at the time of testing and may not indicateelevated lead levels if time has past since exposure. We are glad that you feel that lead hasnot impacted your health. However, we also feel that you should share the conditions ofyour exposure with your health care provider so that person can monitor your bloodpressure and other, less obvious effects.
- If, after all of the studies that have been completed regarding the toxic hazard of lead it can still only be a possibility, then it would appear time to move on to another project.
We appreciate your opinion even though we disagree. Information that we gather now willhelp people in your community and will also help others experiencing similar exposures.
- My uncle is, at present, 88 years old and still as sharp as most young men--and he worked in the lead industry for over 49 years. He started when he was 15 years old. So, really, there's not much of a health hazard here.
We are glad that your uncle is in good health. However, one person who apparently hasnot suffered ill effects cannot be used to predict how exposure may affect others. We haveto examine a larger population that includes people that could be much more sensitive totoxic effects than others. Our public health guidelines are meant to protect all people,including those that may be more sensitive.
- When there is lead in the ground and you drill a well through it, you are going to have lead in your well. But it hasn't killed anyone.
If a well is drilled and cased properly, lead that is bound to soil will not necessarily be inthe water at levels detected by normal analytical procedures. Our concern is water orother environmental media such as air that contains lead at levels that will increase yourbody burden if you are exposed. We realize that everyone will be exposed to lead that is inthe environment, but we need to minimize exposures when possible. As stated before, leadexposure will not cause death unless the dose is extremely high; lead's health effects aremuch more subtle, not usually physically observable, and result in problems that can affectthe welfare of others who are not exposed (such as with the affected child who disrupts theclass or is violent toward playmates).
- What long-term [health] effects can we look for?
Exposure to lead can have a wide variety of health effects. While it may not seem to be aserious problem for one or a few people, it could be a very severe problem for a largepopulation exposed to lead over a long period of time. We have mentioned high bloodpressure (middle-aged men) and lowered I.Q. levels in children. Lead can also causebehavioral problems in children and youth. It could be as subtle as a child's being unableto get along with other people, exhibiting aggressive or violent behavior, or the inability forthe child to communicate properly with others.
- Although we have only lived here for a short time, just how much time must be spent in closeproximity before an effect is felt by the people--the small children, the aged, and the adult? Ihave two very allergic children, allergic also to inhalants. Should I be more of a watchdog overtheir outdoor activities? How much of these toxins are we ingesting from our water supply orvegetables grown in this area and cattle raised here?
First, we want to emphasize that with simple precautions, many of which you likely alreadydo, children should be allowed to enjoy themselves and not be afraid to play. Fortunately,exposure to lead can be greatly reduced by adopting some very simple habits. Theseinclude keeping children from playing on the tailings piles and in the dust, washing handsbefore meals and snacks, washing play-clothes after children have been outside, bathingbefore going to bed, wiping feet before entering the house, keeping the house as dust-free aspossible, keeping toys clean and washing baby pacifiers after they have been dropped, andwashing home-grown fruits and vegetables before eating.
Lead is a cumulative toxin. The amount of lead that enters that body determines whatkinds of effects may be experienced. Effects may never occur or may be so subtle they arenever noticed. If you have lived in the area for a short time, you and your children havenot likely been exposed to enough lead to be of great threat. Unborn children and veryyoung children are most sensitive. An expectant mother and infants and toddlers shouldavoid lead exposure as much as possible. The safeguards discussed in the previousparagraph will help minimize exposure to older children and adults.
To our knowledge, there is no documentation on allergic reaction to lead. However, peoplesuffering from allergies may have reactions from the tailings dust, but this would not berelated to the dust's lead content.
- It is about time someone checked into this, as many feel it is a big problem. I feel someone should take a survey to see the increase of cancer in this area. I know cancer is a major concern of everyone.
We have reviewed available health outcome data, and a documented high amount of lungcancers exist in this area. Lead, however, has not been shown to cause lung cancer. Leadacetate is the only species documented to cause cancer in the laboratory animals. Cadmium and arsenic, heavy metals also found in the tailings material, are associated withcancer. Cadmium is a documented carcinogen through the inhalation route of exposure. This health assessment does recommend that further studies be conducted to determine thecause(s) of increased lung cancer. These studies would have to consider the documentedincreased smoking rate, along with many other variables, in order to determine what, ifany, contribution cadmium or arsenic exposure contributes to the cancer rate.
- There seems to be so many more people having migraine headaches. It used to be fairlyuncommon--now it's almost as common as the cancer problem. Coincidence? I don't think itreally is.
DOH appreciates this person's input and suggestion. Current data do not indicate thatmigraine headaches are caused by exposure to lead or cadmium. DOH has noted thisconcern and will keep it in mind as further studies and activities are performed at this site. As with any ongoing or serious health condition, DOH recommends that affected personssee their physician for diagnosis and treatment.
- Stop this unneeded health study.
Thank you for your opinion. We disagree and feel we would be neglecting our duty as thestate's public health agency to stop the study.
- Two years after moving to this area my lungs began to deteriorate to the point that I cannotcough up excess drainage like I could before moving here. I suspect it is due to the chat dumps. Many other people have told me they or family members have the same problem. Other peopleand I have been told unofficially by doctors that our lung problems are caused by the chat piles. Ibelieve there is a health problem here, and I believe it is costing me my breath.
We strongly recommend that you and others having chronic health problems see aphysician for a complete examination, diagnosis, and prescription for treatment. While thetailings piles do create a large amount of air-borne dust during dry, windy conditions,studies done to date have not confirmed that the tailings material is the cause of specificrespiratory problems. You should not wait until studies on tailings piles are completebefore you see a health care provider about your health problems.
17. My greatest concerns are the lack of knowledge of the mineral species containing the metalsof concern, and the lack of understanding of how readily metals are liberated from the mineralsinto the environment.
We agree that more information is needed on the speciation and bioavailability of the contaminants and have made those recommendations.
- The word "dolostone" should replace the word limestone, as the ore is hosted by dolostone.
ATSDR's Public Health Assessments are written for the affected community. Limestone isthe word most commonly used by the general population for the material and is the wordof choice for the public health assessment.
- I question the findings of HARP and others who claim the metal concentration of the tailingsis sufficient to pose a toxicity threat. They did not consider mineral species and solubility. Health evaluations regarding metals should consider the form of the metal.
We believe the HARP determinations were accurate and appropriate. We do agree thatmore information on the metals would enable us to provide better advise regardingexposure; we made that recommendation.
- Both pyrite and marcasite should be searched for and analyzed for arsenic. If these mineralsdo not contain arsenic, it may be coming from sources other than the tailings.
Arsenic has been detected in the tailings, and exposure to the arsenic, regardless of thesource, is of concern to us. It is not within the scope of the public health assessment todetermine the source of this contaminant.
- The mean value of lead in agricultural soils from around the country is 12 to 50 ppm. Somefruits and vegetables contain mean values of up to 12 ppm lead. Why should groundwater have 0ppb lead when it is a naturally occurring, widespread element?
Notwithstanding the mean value of lead in soil, fruit, and vegetables nationwide, the 0 ppbof lead in water is a goal. EPA's action level for lead is 15 ppb, so it is unlikely thatanything would be done about water with lead levels below that. Our goal is to eliminateexposure to lead and other toxic chemicals whenever possible. We realize that we cannotprevent all exposure to naturally occurring elements.
- DOH could contact those studying tailings mineralogy for a better understanding of cadmiummobility. Perhaps DOH should evaluate this aspect before establishing a blood samplingprogram. You may want to drop the program if cadmium is not available as a free-metal, or youmay want to modify sampling and analytical technique if cadmium is still considered a potentialhazard.
DOH appreciates these comments and suggestions. However, we believe that, instead ofwaiting for an environmental study, which could take a long time to complete, the bestinterest of people's health is served by seeing if people are being exposed. If people aretaking up the contaminants, we can propose actions to stop or lower their exposures andoffer advise to local health care providers on how to monitor the health of those exposed.
- With the many real problems facing our state and nation, spending enormous sums on aperceived problem without any real benefit would be absurd. I see no reason at all for initiating a huge Superfund dollar demand.
DOH and ATSDR believe that when it comes to protecting the lives and health of people,especially children, the benefits far outweigh the costs.
- I suggest that generating concern over the health threats of these old tailings is unnecessaryand uncalled for. The threat of small amounts of lead residue in these old tailings has beengrossly overstated.
We strongly disagree with this statement. The amounts of lead in the mine tailings are farfrom small, and the hazards of being exposed to contaminants in the tailings have not beenoverstated. We do not want to frighten people, but we do want local residents to know thattheir health could be adversely affected by exposure to those contaminants. It is true thatwe do not yet know exactly what levels of exposure have occurred or what health effects wemay see as a result of such exposure. We do intend to take appropriate actions based onour study findings.
- It is obvious that the tailings are gradually weathering and healing.
This statement contradicts itself. It is true that the tailings are "weathering." But in thiscase the weather (wind, rain, and time) are breaking the tailings down into smallerparticles. This is not a process of healing or getting better; it is a case of decay andworsening. The smaller the tailings become, the more easily they can be moved into andthrough the environment, thus making them more available to human exposure throughinhalation and ingestion.
- There is an encroachment of vegetation along the edges and occasionally in the middle. Thisprocess could be assisted by the simple expedient of permitting the scattering of waste tree tops,limbs, waste chips and clippings from power-line rights-of-way maintenance, and even oldsawmill slabs. All of these reduce surface wind velocities and temperatures and trap dustparticles from the air which eventually form a ground cover and assists in the natural start of new vegetative life.
These are good suggestions, though we do not believe that only vegetation efforts will beenough to reduce degradation and movement of the tailings to a safe level. Additionalefforts may include capping the tailings piles with layers of various materials, with soil andvegetation on top.
28. Some simple vegetation-generating and support measures could be initiated which wouldimprove both the appearance and the environmental quality of the area. I don't know as suchaction falls within the mandate of the Health Department.
See the previous statement and response. Further, it is true that it is not within DOH'smandate to initiate vegetation or capping action. However, we do make recommendationsfor actions that are protective of public health.
- I wonder how much money has been spent on this--and now they want to spend $12 millionmore of the taxpayers' dollars for something that time has proven doesn't hurt a thing. If it doeshurt somebody, show it to us in person. If the chat dumps are that bad, how do the people do so well in all walks of life?
All expenditures on this and all National Priorities List sites are part of public documentsand available for public review. On the contrary, it has not been proven that localresidents have not experienced adverse health effects from contaminants in the tailingspiles. As we have previously stated, the effects of lead poisoning are not usually visible. When we complete our studies, we will have a better understanding of exposures we believeare occurring and can perhaps give you actual scenarios of what impact, if any, theseexposures have had.
- We do have a lot of dust and chat that blows in during very windy days. People even havechat in their homes and have no children to track it in. This really has been a problem for years.
DOH and ATSDR appreciate this person's input.
- It is my considered judgement that branding the chat piles as "hazardous waste" is withoutmerit, and the practice should cease. Rather, this material is a valuable resource and should beexploited. Finding new uses for the chat would be a better endeavor than the present fruitlessactivity.
The chat piles contain substances that are known to make people sick when those peopleare exposed to a certain level of the contaminants. For that reason, they are considered"hazardous waste." However, we may develop ways to stabilize the hazardouscontaminants within the chat, and then find safe uses for the tailings material. Ourintention is to be part of efforts to find effective uses for the materials.
- Stabilize the Desloge chat pile area to prevent further losses of material to the Big River.
EPA is proposing to make great efforts to stabilize the Desloge pile and protect the BigRiver from further impact from the pile. Construction is underway.
- Petition the Environmental Protection Agency to remove the Desloge chat pile from theSuperfund list. Certainly there are more productive ways to spend money.
Your comment will be read by EPA. Thank you for taking the time to read the document and provide comment.
- It is distressing that the inferences made and the conclusions drawn in the Health Assessmentare flatly contradicted not only by numerous other EPA supervised health risk studies, but also by many of the studies upon which the Health Assessment itself is supposedly premised.
We are not aware of a risk assessment that has been completed for the site; therefore, wecannot verify that contradictions exist. Risk assessments and public health assessments arecomplimentary documents, not contradictory documents. Risk assessments are conductedin order for EPA to establish what needs to be done to the environment in order to protectpublic health and the environment. Public health assessments are conducted to identifywhether people have been exposed to contaminants and what needs to be done for theexposed people. Because different end-points are needed, information is evaluated slightlydifferently.
- As demonstrated by recent articles in the local press, the Health Assessment has had theeffect of misleading the public and has wrongly heightened public concern over the Site withoutany scientifically significant factual basis. Rather than helping to educate the public about minewaste issues, the Health Assessment instead defeats meaningful public discourse; frustratescooperation between industry and government over environmental issues; and potentially,encourages needless and wasteful litigation.
We do not feel that you expect a response to your comment because you are providing uswith your opinion. We disagree with your opinion and feel the public should be providedwith as much information as possible. Our opinion is that meaningful discussions can onlyoccur when everyone has as much information on the subject matter as possible.
- Environmental Protection Agency: Page 5, Paragraph 5; the text incorrectly states that thelandfill operating at the site uses the mine tailings as a daily cover which is then capped by threefeet of clay and vegetated. The clay cover material is actually spread to depth of three to sixinches prior to establishing vegetative cover. The text should be revised accordingly.
The document has been revised.
- Environmental Protection Agency: Page 15, Paragraph 1; It should be explained here that"J-coded" data as reported by a Contract Laboratory Program (CLP) lab are chemicals whoseconcentration occurs above the CAP contract reportable concentration limits for QualityAssurance/Quality Control (QA/QC). Thus, J-coded data are useful for site characterizationpurposes, but have limited value for enforcement proceedings, because they represent anestimated value above the contract reportable limit for meeting the contract QA/QCrequirements.
The document has been revised.
- Environmental Protection Agency: Page 40, Recommendations; Health recommendations toreduce exposure to contaminated soil and dust in residential settings near the site should beprovided in this section.
This is a good idea, but we do not feel the public health assessment would have thecirculation to reach a large enough portion of the population. Furthermore, theinformation could be buried in all the other information in the public health assessment. For those reasons, DOH will be doing community outreach and education to help lowerexposure to the tailings. This information is available at the St. Francois County HealthDepartment.
- Environmental Protection Agency: Page 39, Last Paragraph; The text should reflect that the EPA Action Level for lead was established for public water supplies and does not specifically relate to private wells.
This information has been added to the text.
- Environmental Protection Agency: Page 39, Paragraph 4; EPA has released for publiccomment an Engineering Evaluation/Cost Analysis for early actions at the site. These actionswill stabilize wind and surface water erosion of the Big River Tailings pile. EPA will decidewhat specific action will take place following the public comment period.
That information has been added to the Actions Implemented During Health Assessment Process section.
- Environmental Protection Agency: Page 39, Paragraph 5; Well sampling results will bedistributed to well owners, including information on reducing lead exposure.
This is just a recommendation. We realize that EPA reports the results of well testing towell owners and did not intend to insinuate otherwise.
- Environmental Protection Agency: Page 39, General; EPA will be conducting a Remediallnvestigation/Feasibility Study (RI/FS) in addition to the early actions at the pile. The RI/FS willevaluate the extent of contamination, risk assessment, and the need for additional work beyondstabilizing the erosional potential of the tailings pile.
This information will be added to the Actions Implemented During Health Assessment Process section.
Comments from Dames & Moore, Consultants for St. Joe Minerals
- The Missouri Department of Health (DOH) and ATSDR's Preliminary Public HealthAssessment for the Big River Mine Tailings/St. Joe Minerals Site inappropriately drawsquantitative health conclusions based on minimal health and environmental data that are neithercompletely revealed nor shown to meet standard data usage criteria. The report should notattempt to draw quantitative conclusions about potential health threats associated with exposure to site-related metals.
Public Health Assessments are designed to present information, derived throughquantitative evaluation, in a qualitative format that the general public can understand. The quantitative aspects of our work primarily involve dose estimations when possible inorder to evaluate possible health outcomes and a statistical analyses of health outcomedata. Dose estimates are based on worst-case scenarios. Health outcome data evaluationsfollow standard epidimiology practices. These quantitative evaluations are appropriateand necessary. The methods we use do not always coincide with risk assessment techniquesbecause our end-point is not the same as a risk assessment's. The two processes are,however, complimentary in nature.
- The health assessment alludes to the need for a cluster investigation study for lung cancer. This investigation is likely to be ineffective, since such a study has already been performed, theresults of which indicate the increased lung cancer rates are attributable to cigarette smoking. [Inthe assessment], the text states, "The Missouri DOH 1985-86 case-control study of lung cancerdeaths in the Flat River area concluded that smoking was the strongest risk factor contributing tothe excessive number of lung cancer deaths." Stating later that the "high" lung cancer rate in thesame paragraph may be attributable to site-specific heavy metals when there is [sic] no data tosupport this conclusion is a concern. In fact, existing data clearly indicate smoking as the maincausal factor. It is an inappropriate juxtaposition to commingle a discussion of higher thannormal rates of lung cancer undoubtedly attributable to increased smoking rates (implying thatone is causally related to the other or at least associated with the other) when no evidence ispresented to support an association between mining materials and cancer rates.
The previous study was not designed to determine whether exposure to the tailings wastecould be a contributing or primary factor. What we do know is that smoking is a big factorin either directly causing lung cancers or putting people at greater risk when exposed toother known carcinogens.
- If EMEGS and CREGs are used in this assessment as health-based criteria, includeinformation on the derivation of these criteria. Also, the text does not explain why differentreference criteria were used for the various metals evaluated in an environmental media. Forexample, in Table 2, a CREG was used for arsenic, an EMEG for cadmium, an MCLG for lead,and LTHAs for nickel and zinc. Since an MCL is available for arsenic and cadmium, includethese values in Table 2. The document appears to incorporate the lowest possible referencevalues in spite of the availability of other, more widely recognized criteria.
EMEGS, CREGS, and other environmental comparison values are derived fromtoxicological information such as ATSDR Minimal Risk Levels, EPA Reference Doses, andEPA Cancer Slope Factors. They are not used to predict health outcomes; they are usedonly to select contaminants present in an environmental medium for further evaluation inexposure pathways. Different comparison values are used because health assessors selectthe most conservative comparison value (the lowest number). By doing that, we ensurethat all contaminants that may be present in a completed exposure pathway are furtherevaluated for health implications. Contaminants that may be present, but at levels belowour conservative comparison values, are not expected to cause any health problems, evenunder worst-case exposure scenarios.
- Data are not presented to support the risk calculations performed. The selection ofcomparative values is overly conservative and the use of worst-case scenarios andultra-conservative cancer risk calculations result in a risk assessment which cannot berealistically applied to any current receptor, on site or off site.
As a public health agency, our mandate is to protect all people, including those mostsensitive, from any exposure that may cause harm. For that reason, we use veryconservative methods when conducting our evaluations. Our goal is to determine what todo for exposed people. Risk assessment is performed differently because the endpoint is tomake clean-up decisions that will protect public health. Risk assessments do not provide amechanism for health follow-up of people that have already been exposed. The publichealth assessment process provides that mechanism.
5. The maps provided with the document do not adequately represent actual sampling locations. The maps do not show the landfill, drinking water wells, municipal wells, soil sample locations,aquatic sampling locations, etc.
The maps provided with the document were never intended to indicate sampling points,etc., but rather to aid the reader in visualizing the site, its location, and, as in Figure 2, howthe tailings piles are located in relation to residential areas. Maps showing the detail youmention are more appropriate for in-depth environmental investigations and would addlittle to this document. We do want to emphasize that we study that type of informationcarefully when conducting our evaluations.
NOTE: Page numbers and paragraphs may be different in the finished document thanthose mentioned in the comments because changes have been incorporated into the finaldocument as a result of the comments.
- page 6, first full para: If the river's degradation was caused mainly by physical changes in thebenthic zone instead of chemical changes, then chronic impacts may not be of concern. Theriverbed composition shifts during periods of high flow, and, eventually, conditions would returnto pre-1977 conditions, providing the tailings are stabilized.
The key to this comment is "providing the tailings are stabilized." So far, stabilization ofthe tailings has not occurred, and the tailings pile still affects the river's fish and biota asdetermined in EPA's 1991 Final Report Listing Site Inspection Big River Mine Tailings. Runoff still occurs from the Big River pile and is also occurring from the other tailingspiles in the area, which also contributes to the effects on the Big River.
- page 6, para 4: The text states that according to a 1982 Fish and Wildlife Service report of theeffects of tailings on the Big River, that "elevated residues of lead, cadmium, and zinc werefound in every biological form examined." The text should specify what levels were measured invarious biological forms and how the study determined that they were "elevated." For example,were they elevated relative to background or baseline levels? If so, what data were used asreference concentrations?
The detected levels for lead, cadmium, and zinc in water and sediment, along withbackgrounds, are listed in Tables 5 and 6. Detected levels of lead and cadmium in aquaticbiota are reported in Table 9. The referral to the tables was inadvertently left out of thetext in the Background section, but was discussed in the text under Off-Site Contaminationheadings of Surface Water, Sediment, and Aquatic Biota with referral to the providedtables. A notation has also been added to Tables 5, 6, and 9 denoting the background sitefor clarification. Aquatic Biota has been added to the heading under the Off-SiteContamination section for inclusiveness.
- page 11, para 3: The statement "Giggers took more sucker species and carp on the Big Riverthan on the other two rivers surveyed" implies that the species diversity of suckers and carp ishigher in the Big River as opposed to the other rivers surveyed. As written, the sentence does not provide meaningful information on the relative numbers of fish taken.
This statement was not intended to provide information on the relative numbers of fishtaken on the three rivers surveyed. The statement is an indication that large numbers ofcarp and suckers were still being taken even though the fish advisory was in full effect andshows that people were being exposed to the contaminated fish. The number of fish takenper hour (4.95) was added to provide a relative number of fish being taken and consumed.
- page 12, para 6: A summary of the 1985-86 case control study of lung cancer deaths in theFlat River area and adjoining communities is presented. The case control study was conductedusing 1976 to 1984 statistical data. On page 40, it states that high smoking rates were associatedwith the study group and may explain the variable. This [sic] data on page 40 should be movedto this paragraph on page 12 so that it is clear to the reader that, in fact, the overwhelminglikelihood of excess cancer is attributable to cigarette smoking. If the study is to be cited, itwould be appropriate to present more than cursory summary information so that the reader candraw the conclusion, otherwise the implication is left throughout the report that site metals are anexplanatory variable for the cancer rate, when in fact there are no data to substantiate this. A well-established explanatory variable (cigarette smoking) is clearly present.
The sources of the health outcome data are listed in the early section (page 12), and thenevaluated and expanded in the Health Outcome Data Evaluation section.
The statement on high smoking rates is not appropriate information to include on page 12because that information is intended only as a list of available data sources.
Note that the 1985-86 Cancer Case Control Study was done only in Flat River and nearbyareas. The study findings allude to the presence of an increased rate of lung cancer but donot provide information on the types of lung cancer identified. The study does indicate athree-fold increased rate of lung cancer in former miners.
We will amend the conclusion and all other references that may suggest we support acausal relationship between lung cancer and heavy metals from the 1985-86 cancer study. However we must emphasize that we do not believe a definite cause was establishedbetween increased smoking rates and increased cancer incidence. In any case, the questionremains as to why males involved in past mining operations have an increased rate of lungcancer.
Substantial additional information/data have been developed about lead, cadmium,arsenic, and about smoking since the 1985-86 study. New data should be evaluated whenaddressing the health status of the people in communities surrounding the site. The factthat a study was conducted does not mean that all questions have been answered.
- page 15-16, Ground water:
- The discussion in the first paragraph under the groundwater heading is based on results forone drinking water well sample and several monitoring wells and springs in or peripheral to alandfill on the tailings pile. Combining the results for potable groundwater and the landfillgroundwater is confusing. The confusion arises later in the paragraph where it is stated, "Onlyheavy metals were detected at levels of concern." This statement is unsupported and mayimproperly lead the reader to conclude that the appropriate level of concern has been appliedcorrectly in the comparisons. Such a comparison is inappropriate in this type of document. Thereader should be able to make an objective evaluation of the data used in these comparisons. Table 2 shows that results from the landfill groundwater sampling program were incorrectlycombined with the drinking water well sample and that comparisons of measured levels of metalsin groundwater were made to a mixture of drinking water standards from various regulatoryagencies. Comparisons made on a mixture of standards is not accepted practice. Table 2 shouldbe revised to include only results for drinking water samples (the landfill office well, Flat RiverWater District Public wells, and the private wells samples from the area) and should clearlyidentify whether the samples are tap or well water. Furthermore, MCLs should be listed in Table2 for all metals for which they are available. An MCL of 50 µg/L is available for arsenic and 5µg/l for cadmium. The Action Level for lead 15 µg/L should be used as a comparison valuesinstead of the MCLG (zero) since groundwater discussions in this assessment on page 20 referonly to the Action Level. It is not appropriate to state that levels of cobalt measured in groundwater samples "were detected at levels of concern," since there is no regulatory or health-based criteria for cobalt (OSWER 9360.1-02, 1993).
The discussion in this section and Table 2 is to indicate the level of contamination ofgroundwater on site. The landfill drinking water well is indeed on site and even though itis deeper than the other wells, may give an indication that it is also being affected bycontaminants on the site. Table 2 clearly states the types of wells. Other commentsregarding the use of comparison values and their derivation have already been discussedand that information does not need to be repeated.
Even though there is no ATSDR comparison value, MCL, or other health or regulatoryvalue for cobalt, the levels of cobalt are elevated over what may be considered normal. Instudies to determine the level of cobalt in water supplies, levels from 35 geographical areasranged from 2.6 to 107 ppb with an average of 21 ppb. That was found in only 9.8% of the3,834 grab samples. In another study, cobalt was not detected or was found up to 19 ppb,with the average being 2.2 ppb (ATSDR 1992c).
In the text, the two on-site monitoring wells were listed incorrectly as sampled forpesticides, volatile organics, base-neutral-acid, total metals, and dissolved metals in 1990. That has been corrected to read 1991 (E&E 1991), as the monitoring wells were onlysampled for metals in 1990.
- It is questionable if the results of the landfill water samples are pertinent since there is noexposure pathway to a human receptor. If the landfill results were included to characterize metalcontent in the perched aquifer near the landfill, this discussion should be in a separate paragraphwith supporting Hydrogeologic information characterizing the permeability, thickness, and extentof saturated units neighboring the landfill. The landfill water sample results should be comparedto suitable background (upgradient) results to effectively demonstrate what metal(s), if any, arepotentially attributable to sources within the landfill debris/tailings.
This discussion is intended to show the level of contamination in on-site groundwater andto determine by comparing them to ATSDR comparison values if the groundwater needsfurther evaluation. We cannot assume that on-site groundwater does not present anexposure pathway, especially since the landfill drinking water well may be affected by thesite contaminants.
- Claiming that "contaminants of concern are arsenic, cadmium, cobalt, lead, nickel, and zinc"is premature. While these six metals appear to be the parameters detected in groundwater, noinformation is provided to allow the reader to compare background concentrations near thelandfill. Thus, the determination that the metals are contaminants of concern may be invalid. The metals should be considered contaminants of concern only if levels in potable ground wateron-site are elevated relative to local background levels. Furthermore, the referenced statement isnot true for the drinking water well, as five of the six listed metals were not detected in that well or were detected at concentrations below comparison values.
The statement that these six metals are of concern is from the Listing Site Inspection reporton the Big River Mine Tailings (EPA 1991), where it states, "Metals of concern detected ingroundwater samples include arsenic, cadmium, cobalt, lead, nickel, and zinc." Additionally, ATSDR uses the term "contaminants of concern" to indicate chemicals thatare included for follow-up evaluation in exposure pathways. We do agree that theterminology can be confusing if the contaminants, after further evaluation, are only ofenvironmental concern and not of health concern.
- page 16, On-Site Air:
- The total number of air samples analyzed should be indicated. For arsenic, the statement thatthree samples exceeded the CREG does not inform the reader what concentration of arsenic wasmeasured or where these concentrations were measured. Results of the 1990 study should betabulated in this report. Were the three samples collected at the landfill location or at the other on-site location?
The document has been revised to indicate the total number of air samples taken duringthe E&E/FIT investigation for the Listing Site Inspection Report. We have also includedthe levels and the locations of where the arsenic was detected. For a full report of the airsampling data, refer to the 1991 Final Report Listing Site Inspection.
- Provide the NAAQS standard for lead of 1.5 µg/m3 per calendar quarter in lieu of an ATSDRcomparative value, as presented in the off-site air discussion on page 19. The lack of an ATSDRcomparative value does not justify ignoring other applicable standards.
We do not feel that the NAAQS number is an appropriate comparison value because thevalue is determined for sampling collected for an entire quarter. The sampling programwas not designed to provide an average level of lead in the air at the site for a quarter. Lead in the air is important when evaluating multiple exposure pathways.
- page 16, para 3 (last): The report notes that ATSDR's CREG level for cadmium and arsenic issubstantially less than the detection limit used in the study. This severe mismatch occurs notbecause the detection limit is inappropriate, rather this is because the CREGS are calculated insuch a conservative manner. The end result is that when CREGS are used as "health-basedcriteria," and compared to reasonable analytic detection levels, a serious disparity occurs. TheCREG is based on sufficiently conservative assumptions that in reality arsenic and cadmiumlevels in air throughout a substantial portion of the United States would fail the criteria. Discussthis issue in more detail in the text so that the reader understands that these numbers areextremely conservative. Emphasize that CREGs are used as an overly protective screeningcriteria, and that levels exceeding a CREG does not imply that there is an attributable excess riskof cancer. As written, the document does not offer any data or calculations that supportimplications that exposure to metals in air near the site could cause excess cancer cased inexposed individuals. On page 34 of the document, the maximum measured value of cadmium isused in a screening calculation which leads to the inference that if individuals were exposed tothe maximum cadmium level, this exposure could correspond to 16 excess cancers per million. To use such a calculation as evidence that the observed elevated cancer incidence in individuals living near the site may be due to exposure to site-related metals is unjustified.
CREGs are conservative comparison values. We added to the text that comparison valuesare conservative. The calculations were performed based on estimated doses and specific,conservative exposure scenarios. As with any "risk" calculation that computes to such lownumbers, the "risk" may in reality be zero. However, because cadmium and arsenic areknown to cause cancer under some conditions, we estimate a possible "risk" number andprovide qualitative information to people who may particularly sensitive.
- page 17, Soil Levels Off-Site: The text states that the highest levels of cadmium and zincmeasured in surface soils from the nearest residence closest to tailings is 270 µg/kg and 13,000mg/kg, respectively. We have conducted an independent screening calculation, assuming that anaverage child resident would conservatively ingest 200 mg soil/day, 350 days/5 years, for sixyears and weigh 15 kg, the chronic daily intake of cadmium and zinc would be 0.003 mg/kg-dayand 0.2 mg/kg-day. The EPA oral RfD for these two metals is 0.001 and 0.3 mg/kg-day,respectively. The RfD represents the level of exposure not expected to cause adverse effectseven in sensitive sub-populations. These data indicate that the maximum measured level of zincin soil does not pose a health threat to individuals living near the site. Dose based on themaximum measured level of cadmium in soil exceeds the RfD by a factor of three. At the nextclosest residence, the maximum cadmium level in surface soil was 25 mg/kg. Using thismeasured value, the chronic daily intake is estimated to be 3 x 10-4 mg/kg-day, which is wellbelow the oral RfD for cadmium.
The cited text is only reporting the levels that were detected in the 1990 LSI. Whetherillness is expected to result from exposure to specific contaminants is discussed in the PublicHealth Implications section, Toxicological Evaluation subsection.
- page 18, ATSDR reference levels:
- The value listed for cadmium of 1 ppm based on a pica child EMEG is highly conservative and inconsistent with the available published literature on cadmium toxicity. In the most recentversion of ATSDR's Toxicological Profiles for Cadmium, ATSDR has withdrawn the EMEG of10 ppm. Furthermore, use of an EMEG based on pica behavior in children as the health-basedcriteria is not substantiated by medical evidence. Pica behavior is a medical condition notamenable to general soil remediation. (Harrisons's Principles of Internal Medicine, the Ed.). It iswell-established in the pediatric literature that pica must be treated by first, a medical evaluation,and then secondary, specific dietary and behavioral modifications. Hence, there is no level ofenvironmental cleanup that can be "protective" for a pica child. It is completely inappropriate tobase a health standard on a reasonably uncommon condition that can only be evaluated andtreated by medical intervention unrelated to soil concentrations of metals. If criteria based onpica behavior in children were routinely used as "standard," then a substantial portion of soil inthe U.S. would require remediation.
- The same argument applies to the EMEG for zinc, which is also based on a pica behavior inchildren. In addition, this document does not acknowledge that within the last six months, theEPA raised the reference dose for zinc by 50 percent. A similar argument can be made for thearsenic CREG level of 0.4 ppm. Based on this level, a substantial portion of thenaturally-occurring levels of arsenic in U.S. soils would require public health warnings andpotential remediation. The numbers used in this assessment are inappropriate as a screen sincethey "screen" very little. Substantial urban and rural areas of the U.S. would not pass theATSDR "screen." By setting the screen at an ultra-conservative level, it forces entirepopulations into a category requiring possible health evaluations. The inherent conservatism ofthe criteria used in this assessment should be clearly explained so the reader can make informalcomparisons.
Again, the environmental comparison values are not used to evaluate health but are usedonly to select contaminants for further evaluation of any health implications shouldexposure occur at those levels. Likewise, the comparison values are not to be used, nor dowe suggest their use, for clean-up levels. We do feel that scenarios involving pica childrenare appropriate for certain conditions, especially if contaminants could be brought intohouseholds where very young children crawl on floors.
- page 18, Indoor Dust Section:
- Please provide from the 1985-1986 study a brief description of what the vacuum bag samplescontained. Did they contain dust, dirt tracked in by residents or pets, human or pet hair,vegetation, visible tailings, miscellaneous mater? The term dust defines inhalable particulate,i.e., particles 10 µm or less in size that can be re-suspended and inhaled. The measuredconcentrations of dust can be used in human health risk assessment for estimation of exposure toparticulate phase chemicals. From appearances, the results from the vacuum samples do notconstitute a viable substitute for actual indoor dust sampling, as is implied here and in theremainder of the document. This bias is acknowledged with the statement that one samplecontained miscellaneous material which caused extreme bias in lead concentration. The vacuumsampling methodology violates an important QA/QC consideration for risk assessments, that "thecollected samples are representative of the situation due to site conditions, not conditions posedby the sampling equipment" (Risk Assessment Guidance for Superfund (RAGS), 1989, p. 4-22). Nonetheless, the document refers to the biased sample results as "indoor dust" samplesthroughout the assessment. The vacuum samples do not equate to indoor dust and the inferencethat they somehow are representative of the levels that residents may be exposed to while indoorsis inappropriate. While the use of indoor dust sampling data is common, particularly for theassessment of lead exposures, the methodology employed in this particular study is flawed foruse for health predictions. The use of vacuum samples overestimates realistic exposure pointconcentrations so they are not useful. All reference to "indoor dust samples" should be deletedand replaced with "vacuum bag" samples in this report and the section(s) on indoor dust thatinclude, make reference to, and use the vacuum data should be deleted.
The document has been revised to say dust/dirt samples.
- There are no data in this section indicating where the homes sampled are located (i.e., theirdistance from tailings piles or other sources of site-related metals). The reader must return topage 7 to find the study and what was done. The distance from tailings is important because aconclusion is later drawn on page 38 that "Metals associated with the tailings piles were found inconcentrated dust samples from homes." As presently written, this conclusion is false sincethere is not a report of tailings identified in the vacuum bag samples, or an established physicaltie between the residence and the tailings pile. Thus, this sentence should be stricken from the report as insupportable.
The intent of this statement is to say that similar metals have been found in the dust ofhomes in the area. At this point it is not possible to establish the source of these metals. Whether one or more sources are involved, as well as the percentage of contribution by thedifferent sources, must still be established. We reworded the conclusion for clarity.
- page 19-20, Off-Site Air:
- The 50 µg/m3 TSP standard is not retroactive to 1981 as implied here. TSP is not a carcinogen and the statement that the 1991 standard "would have been exceeded in 1981" isinappropriate for this assessment. Currently, there is no federal standard for TSP.
The statement has been changed so that it does not imply that the TSP was retroactive.
- The report should include a table showing the results of the 1990 LSI study. Since the arsenicand cadmium CREG is below the detection limits used by E&E in the 1990 LSI study, it cannotbe determined if these two metals occur at above-CREG levels in the off-site or backgroundnon-detect samples. Were there sampling or laboratory problems that resulted inhigher-than-normal arsenic detection limits or is the CREG arsenic level regularly achievable in the laboratory?
When laboratory problems occur, they are noted in the Quality Assurance/Quality Controlsection of the document. CREG levels are achievable in the laboratory for most chemicals. Testing at those levels is sometimes very expensive.
- Are the reported metal concentrations in TSP or PM-10? PM-10 is typically used, ifavailable, since it better approximates the inhaled fraction. If TSP results are used for exposurepoint concentrations, an overestimation of risk could result and this should be stated with the qualifiers.
The information in the referenced material lists the data as total suspended particulate(TSP) annual geometric mean for the years 1981 through 1983. Again, we are simplylisting the data that have been accumulated on the site and area. For more informationrefer to the 1990 LSI.
- page 20-21, Ground water:
- EPA's replacement of the MCL for lead in groundwater should be referenced (USEPA Drinking Water Regulations and Health Advisories, May 1993) and clarification should beprovided that the Action Level of 15 µg/L applies to tap water, not to groundwater in wells asthe text implies. The Action Level should be cited in Table 2 as a comparative value fordrinking water samples only.
The document has been referenced to indicate the USEPA Drinking Water Action Level of15 µg/L and the statement clarified to indicate that the action level applies to publicdrinking systems. Since private drinking water wells have no enforceable standards, theaction level for lead and MCLs are used as safe indicator numbers. Table 2 has also beenrevised to include the action level.
- None of the available hydrogeologic information (USGS, Missouri Geologic Survey) is givencharacterizing the aquifer(s) which are tapped by public and private users. Is the aquifersufficiently deep to derive recharge from areas distant from Desloge such that influence fromlocal metal sources is not a problem? Do domestic supplies come from mine workings (assuggested by the Rivermines water district well) which could be affected by many surface orshallow metal sources? These questions needed to be addressed in the assessment. The focus ofthe public health assessment is the Big River mine tailings pile, but this discussion draws no conclusion as to the source of metals in the domestic water supply. Is the source tailings,unmined mineralization in bedrock or oxidized mineralization in mines? The reader must guessthe source of lead and zinc. In the absence of aquifer characteristics or water chemistry forunaffected wells upgradient of the site, a reader could infer that since none of the ground watersamples contained elevated cadmium, zinc or lead, the low concentrations in ground watersamples stem from natural bedrock sources.
The focus of the public health assessment is to identify how people are exposed to chemicalsin environmental media that can cause health problems. We provide public healthobservations for EPA and communities; we do not identify source areas.
- The statement, "Results of the analysis showed that no wells contained detectable levels ofvolatiles, semi-volatiles, or pesticides" is misleading, as only two of 42 wells were sampled for the constituents listed.
We have revised the document to indicate that only 2 out of 42 wells were sampled andwere not contaminated by volatiles, semi-volatiles, and pesticides.
- "In the most recent sampling of the site by EPA, 12 residential wells were sampled." Noreference is made to this study in the Site Description and History section page 7, which lists theother site investigations. The most recent EPA reference in the bibliography is 1991. Whenwere these important samples collected and why were these data not included in this report?
This most recent sampling information has been added to the Site Description and Historysection and the Private Well section under Off-Site Contamination and referenced.
- page 22, para 1, Surface Water: The sentences, "The levels for total lead had increased for allwater levels. The total lead concentration of 680 ppb under high flow conditions was the highestduring the investigation," are confusing. The report mentions that samples were taken 5 milesdownstream from the site, 16 miles upstream from the site (background), and 37 milesdownstream from the site. Are these sentences meant to report that lead levels increased fartherdownstream or that they increased at the sampling location 5 miles downstream of the site? Clarify this paragraph. Since an upgradient (background) station was sampled, the downstreamresults should be compared to it. Increased metal concentrations alone do not equate toenvironmental degradation. Were Missouri Water Quality Standards (10 CSR 20-7) exceededfor the short reach downstream of the tailings pile? Provide a comparison to Missouri aquaticlife criteria. the comparison to concentrations at Brown's Ford 60 miles downstream is irrelevant due to the likely presence of other metal sources over this long reach.
The paragraph has been clarified to better illustrate the increases in detected metals belowthe Big River tailings pile. The comparison to Brown's Ford indicates that the influence ofthe tailings piles has decreased as distance downstream from the source of contamination(tailings piles) increases. No reference was made to Missouri Water Quality Standards, butwe have added them to Table 5.
- page 22, para 5 (last): Refer to the 1962/1963 and 1977 water quality studies. Four, not two,water quality studies appear to have been reviewed for this report.
The document has been revised for clarification that only two studies were done.
- page 22, Surface Water: Surface water results should be compared to Ambient Water QualityCriteria (AWQC) for the protection of aquatic life. EPA reports chronic AWQC of 1.8, 74, and180 µg/L for cadmium, lead and zinc, respectively, at a hardness of 50 mg CaCo3. Acomparison of AWQC to surface water levels reported in Table 5 shows that measured levels oflead in dissolved water, the fraction that is available for uptake by biota, do not exceed AWQC atany sampling location. Measured levels of cadmium in the dissolved fraction and zinc exceedAWQC only at the Desloge station.
We have added the Missouri Water Quality Standards (MDNR 1992) for the protection ofAquatic Life to Table 5; however, those water quality standards do not represent anyvalues that can be used to evaluate human health issues. For that reason, they are notnecessary to use in our evaluation, but people may have an interest in them.
- page 25, Indoor Dust para: The statement that "since houses near the site are about 20 to 30years old indicates that individuals may have been exposed to contaminated indoor dust for thatperiod" is misleading. It implies that the same individual(s) have lived in those houses within amile of the site ever since the house was built. Exposure duration's should be based on the length of time spent at one residence, not on the structure.
The statement following the sentence you quote, says the "people could have beenexposed." The people who reside in the area know how long they have been there. Weoffer the possibity that at least some of the people have been there 30 years.
- page 28, Groundwater Pathways:
- A paragraph on site geology early in the report would aid in understanding the previous 28pages. The simplistic scenario provided in the first paragraph does not convince the reader thatrelatively immobile lead ions leach from the tailings through limestone to groundwater,especially since lead concentrations in distant private and residential well samples are apparentlyequal to or greater than that recorded for the landfill office well. Zinc, present in the tailings andsoil at elevated concentrations, is much more mobile in solution than lead and typically occurs atelevated concentrations in leachate samples at this and other lead-zinc mining sites (see Table 2). However, the zinc concentrations in the landfill office well sample are very low (140 µg/L), probably at background levels.
The document has been revised.
- The last sentence of the first paragraph states that the landfill office well water is"contaminated" based on one sample that exceeds the Action Level for lead (concentration oflead in that one sample equals 17 µg/L lead vs. EPA action Level of 15 µg/L). Exceedance ofthe lead action level does not, in itself, indicate lead contamination. Rather, in cases where leadlevels exceed the Action Level, EPA promulgated a zero MCLG and a treatment technique. Thetreatment technique includes a 15 µg/L action level at the tap (57 Federal Register, 60886). Re-sampling is advised to determine the source of lead (plumbing, formation water, etc.). TheEPA has not yet reached consensus on an appropriate health-based numeric criteria andaccordingly has not promulgated human health criteria for lead in drinking water.
The well has been resampled and still contains lead above the EPA Action Level of 15 ppb. We consider the presence of lead in drinking water above the Action Level ascontamination.
- Without performing a statistical analysis or without data characterizing upgradient waterchemistry, it cannot be determined that on-site groundwater contains any more lead or zinc thanoff-site groundwater. Therefore, the reference to an "off-site groundwater pathway" causingregional water quality problems is premature.
We have modified this statement.
- For the municipal water supply, only lead is mentioned as being detected. This conflicts withan earlier statement on page 20 that says that other metals were detected in the 1991 sample ofthe Flat River Public Water System. Zinc occurs in detectable quantities in most groundwatersamples in this area. Provide the metals data in a revised Table 2 (drinking water only) so thatthe reader can draw a conclusion regarding the reported metal concentrations in the publicsupply.
Other metals may have been detected but were below comparison values. We have revisedthe statement on page 20 for clarification. Table 2 lists the contaminants found in on-sitegroundwater and has nothing to do with the public water system. Analysis of the waterfrom the public water system is available to anyone wanting a copy from the public watersupplier.
- In review, the exposure pathway to zinc and lead in groundwater is complete because arearesidents use ground water for drinking. The attempt in this section to isolate on-site exposureversus off-site exposure is weak and unsupported and should be deleted and replaced by adescription of the complete exposure pathway only. Exposure to other metals in municipal orprivate drinking water (arsenic, cadmium, cobalt, and nickel) appears to have been neglected in this assessment because they were not detected, although no data are presented in the report to support this.
A completed exposure pathway exists. Lead and zinc are in some off-site wells and theon-site landfill well at levels above comparison values. When metals (e.g., arsenic,cadmium, cobalt, and nickel) are not present above comparison values, we do not expectadverse health effects to occur even if people are exposed to the chemicals.
- page 29, Fish Pathways: "The number of people who are catching and eating thecontaminated fish is not known." Considering that the proportion of resident and nonresidentdiet that consists of contaminated bottom feeders is unknown, then the human health riskassociated with this specific pathway is unknown and should be stated as such. Thequantification of risk via ingestion of site fish is not difficult but would require eithersite-specific exposure frequency information (as recommended in RAGS, Exhibit 6-17) or theuse of the default factor of 48 days/year per capita (RAGS, 1989). The report does not makerecommendations for future surveys to answer the exposure frequency question.
Your comment about the human health risk associated with this particular pathway wasgood and the document has been revised to reflect that information. To determine theactual health effect of this pathway a study would need to be done to determine the actualdifference of lead levels between fish- and non-fish eaters. Or, as a second choice, a riskassessment could be completed. Little is known about the additional effects consuminglead-contaminated fish has on those already exposed through different pathways. With thefish advisory in effect, people are aware of this pathway and hopefully will avoid it.
- page 29-30, Toxicological Evaluation: It is well established that zinc, cadmium, lead andarsenic in the form associated with mine tailings is very poorly absorbed through the skin. Thisalluded to in the lead and groundwater discussion on page 31, but should also be specified for theother metals. When exposure occurs, individual characteristics such as age, sex, nutritionalstatus, health status, lifestyle, and genetics influence how the chemical is absorbed, distributed,metabolized, and excreted. ATSDR minimum risk levels (MRL) are not appropriate forchildhood exposure to cadmium. Cadmium is a long-term chronic toxin to adults but not tochildren. The literature on cadmium toxicity is clear that the calculated reference doses and otherthreshold criteria are based on lifetime (or at a minimum) a thirty-year exposure (Nogawa, 1989). Children are not the appropriate target for these type of calculations for cadmium.
We agree that the metals found at the site and in the area are poorly absorbed through theskin and have removed references to a completed dermal pathway. We have also includedan explanation under Completed Exposure Pathways that dermal exposure is not aproblem. Regarding your discussion of MRLs and cadmium, the pages you mentioninclude only a general discussion of different methods ATSDR has of determining ascreening level that should be a "safe" level.
- page 32-33, Lead: The information regarding the toxicity of lead presented in this documentis general and is not clearly attributable to different types of exposures. For example, it isunusual to find some of the mentioned neurologic effects (i.e., foot drop and wrist drop) otherthan in severe (high) occupational exposures. This section should more clearly show under whatconditions these symptoms have been reported since many are relics of historic past andoccupational settings that are no longer common or exist in this country. There is also astatement that says, "Few studies are available that indicate how much lead in dust and soilswould result in an increase of blood/lead levels when lead is ingested or inhaled." This isincorrect. There have been numerous studies performed in the United States that have looked atthe relationship between mine waste material and blood-lead levels (Steele, 1990, Johnson,1991). Due to the significantly reduced bioavailability of mine waste materials, it is notappropriate to assume that the presence of mine waste materials automatically results in elevatedlead levels in potential receptors. The mini-blood lead study conducted at this site demonstratedthat local lead levels were not significantly elevated.
We do attempt to evaluate site-specific situations when evaluating the toxicologicalimplications that exposure may have on the people in a community. Because we do not yetknow what subtle health effects may occur at specific blood-lead levels, lead discussionstend to be more general in nature. We agree that the mine waste at this site may have lessbioavailability than other sources (paint, smelting), but the mini- blood-lead study is astarting point in determining the effect the tailings have on the community. An exposurestudy is underway to determine the effects on children that are most likely to be exposedand who are expected to suffer the greatest effects.
- page 32, para 1: The document states that residential lead soils in the range of 400-500 ppmare not considered harmful to children. The next sentence says that lead was found on-site at amaximum of 13,000 ppm and comes to the conclusion that this high lead level is typical ofmeasured on-site soil levels and that therefore, a major public health problem is present. This seems to be a conclusionary statement not supported by the facts presented.
We have modified this statement.
- page 32, para last: The reference cited for the effects of lead exposures on IQ is dated andshould be updated to reflect more recent, post-1990 data.
We agree and have revised the document.
- page 33, para 1: It should be emphasized that lead has not been shown to be a carcinogen in humans. The B2 designation is based on animal studies.
We have revised the document.
- page 33, para 2: Reference to pica behavior should be caveated to indicate that pica is not acommon condition and that it is a medical condition that is not amenable to treatment by soilremediation. Comments concerning organic forms of lead should be deleted since the potentialcontaminants of concern are all in inorganic compounds.
The sentence on pica children is an identification of the population at greatest risk fromexposure--pica children. Although pica is considered a rare medical condition, youngchildren, especially crawling-aged children, exhibit a greater hand-to-mouth behavior thanolder children. On organic forms of lead, the statement is saying that exposure to organicforms of lead in the occupational setting may be in addition to exposure to inorganic lead atthe site, causing extra exposure to and increased levels in the body.
- page 33, para last, Cadmium: The target population for cadmium is not children but ratheradult residents due to long-term chronic exposure. The statement, "Inhalation of low levels ofcadmium over 70 years could lead to similar problems," referring to calcium bone loss andfractures is unsubstantiated at the "proposed" dose levels potentially ascribed to the site.
The statement reads "several years," not "70 years."
- page 34, para top, Cadmium: EPA has classified cadmium as a B1 carcinogen for inhalationonly. Ingestion of cadmium had not been shown to cause carcinogenic effects.
We agree and have revised the document.
- page 34, para 2, Cadmium: The use of a 70-year exposure duration (the term exposurefrequency is incorrectly used here) is inappropriate. EPA has determined that the upper-bound(90th percentile) length of time spent at one residence is 30 years. Also, the equation presentedto estimate risks (unit risk times air concentration times exposure duration) seems to be incorrect,as the result has the units of years, which are not indicative of risk. In fact, the "16 cases permillion" result was correctly calculated by multiplying the unit risk value by the air concentrationonly. Therefore, the reference to the exposure duration is not needed.
We agree and have revised the document.
- page 34, para 4, Arsenic: Further information is required on naturally occurring backgroundlevels of arsenic. The third paragraph in the arsenic section says, "Inhalation of low levels ofarsenic is believed to increase lung cancer." Arsenic lung cancer studies are based onoccupational exposures at high concentration and duration. (ATSDR, Toxicological Profile). Otherwise, general environmental airborne arsenic impacts have typically been associated withactive smelting activities as opposed to tailings piles.
We have expanded this paragraph.
- page 35, para 2, Arsenic: See comment 27.
We agree and have modified this paragraph.
- page 35, Zinc: It should be emphasized that zinc is an essential element. This section needsto be updated to demonstrate the reported changes in normal dietary intake levels. It should bestated in this section that it is highly uncommon in the literature to find (if found at all) episodesof zinc overdoses attributable to environmental causes. Most reports of zinc intoxication in the United States are secondary to vitamin supplements. (ATSDR, Toxicological Profile).
We agree and have expanded this paragraph.
- page 36, para 1: This section states that lung cancer rates are highly dependent or confoundedby smoking rates. Therefore, it is impossible to draw conclusions regarding "undergroundminer" without knowing relevant behavioral data.
We are only reporting results of a study, not endorsing it.
- page 37, para 2: Of the 16 employees and residents whose blood lead levels were measured,only two individuals had blood lead levels higher than 5 µg/dL (levels = 10 and 12 µg/dL). Thecurrent EPA recommendation through the Centers for Disease Control and Prevention is a targetfor children of 10 µg/dL with a 5 percent Exceedance. The document does not indicate whetherthe individuals tested were children or adults. Being an employee of St. Joe State Park impliesthat at least some of the individuals tested were adults. It is also noted that there may be otherfactors influencing the blood lead levels that were over 5 µg/dL that are not site related. It issignificant, however, that when actual biological sampling was done, very low blood leads werefound. This implies that the actual dose received by potential receptors appears to be low. Nowhere in the document is a discussion of the bioavailability of mine waste mentioned. It hasbeen clearly demonstrated in the literature that the bioavailability of the individual metals(including lead) affects the toxicity of the mineral material.
We agree and will amend this paragraph. The document will indicate whether theindividuals tested were children or adults.
Blood lead measurement indicates recent exposure (past 6 to 8 weeks). Attempting toaddress past exposure with a blood lead determination would not be appropriate. Pastexposures to lead would better be addressed by using other techniques (x-ray, bone tissuebiopsy, etc.). Finding low blood-lead levels does not exclude past exposure.
Since past exposure of workers at the site is not known, investigation of past occupationalhistory is important. In the event that past exposure existed, it can be assumed that leadmay be stored in the bones of the body, and that it can be mobilized to the blood. In thiscase, effects associated with blood-lead levels may be expected.
It is also important to consider that lead dust can be carried home from an occupationalsetting and "could easily cause low level lead accumulation in the spouse's body" which iswidely known to present prenatal risk to child development (Ashford NA, 1987) .
In regard to the bioavailability of lead compounds in the mine tailings, we agree that this isa question that continues to be researched. We hope that the current ATSDR-funded leadexposure study in the area may provide some additional answers to add to the on-goingscientific discussion about the bioavailability of lead compounds.
- page 38, Conclusion 1: The elevated rates of lung cancer are initially attributed to excessivesmoking (DOH 1985-86) then in the same conclusion, it is stated that it is not known if there isan association between smoking, carcinogens in ambient air, and lung cancer rates. If the resultsof the 1985-86 study were flawed or inconclusive, state this. Otherwise, if smoking wasdetermined to be the cause in the initial study, why are other airborne carcinogens now beingconsidered?
We have modified this paragraph.
- page 38, Conclusion 2:
- "Total lead has been found in residential soils at levels above what would be safe for a child's exposure." As written, this assessment offers no support for this statement. No referencelevel is listed for lead (page 18) nor are other regulatory criteria for lead (for other sites)identified.
We have revised the statement, and there is no listed safe level or comparison value for lead because one is not known at this time.
- The statement that observed arsenic concentrations are above ATSDR's reference levels couldprobably be made for any soil type in the region. ATSDR's conservative CREG (pica child) of0.4 ppm for arsenic is well below the average arsenic concentration in Missouri agricultural soils. The geometric mean of 1140 samples is 8.7 ppm (U.S. Geological Survey, 1984) and thereported background arsenic levels in soils from the 1990 LSI study is 6.2-9.5 ppm.
The CREG is an environmental screening value to determine what chemicals should befurther evaluated for public health implications. They are not used to imply any publichealth condition.
- page 38, Conclusion 3: The conclusion that the metals in concentrated dust samples from homes is related to the presence of the tailings piles is not supported. No scientific evidence isprovided in the report to indicate that tailing material (or tailings dust) is present in the vacuumsamples. Table 4, by its comparison of reference values, implies that all metal content above the comparison value is attributable to tailings, but the text offers no firm evidence to show that the reported levels are higher than in homes distant from the site.
We have modified the conclusion.
- page 38, Conclusion 4: Lead levels in fish do not have to be elevated to: "contribute to thedaily intake." Any lead in fish or other food items, drinking water, etc., could contribute to thedaily intake. Please clarify this statement.
That is exactly the point we are trying to get across. When you have elevated levels of leadin fish, soil, tailings, food, and water, the higher the lead level, the more the contribution to the daily intake. We have clarified the statement to include other items.
- page 38, Conclusion 5: Clarify that the EPA Action Level applies to tap samples.
We have revised the conclusion and the document to state that the EPA Action Level for lead is for public drinking water systems at the tap.
- page 39, Recommendation 1: The first recommendation calls for "actual air exposure levels" when data on arsenic and cadmium concentrations in air are currently available from the 1990LSI study. Is this recommendation meant to imply that the 1990 data are insufficient to meet thegoals of the study. If not, state the reason and what new methodology should be used in aproposed future sampling effort.
We have modified the recommendation, but the air levels listed in the 1990 LSI were for ashort-term, low-wind condition. That sampling is not representative of conditions that mayexist over a long period of time. A long-term ambient air monitoring program, thatincludes the known contaminants present, would be a much better indicator of actualexposure levels to anyone exposed to the dust.
- page 39, Recommendation 2: A postulated exposure pathway is offered here, but no riskassessment is made in the document that would convince the decision maker that there wasindeed a health risk. In fact, blood-lead sampling of workers on tailings suggests that thelikelihood of elevated blood-leads attributable to tailings exposure may be low.
We have modified the recommendation somewhat, but as mentioned before, the documentis not intended to assess risk for EPA decision makers. We would have to know whatstudy, in particular, you are referencing before we could comment on the worker study.
- page 39, Recommendation 3: Confirmation of earlier (vacuum bag) results is not needed. If re-sampling is deemed necessary, conventional swipe dust sampling of on-site and backgroundlocations is recommended so that results can be compared to samples collected from homes atother mining sites.
Indoor dust sampling is necessary in order to determine the amount of contaminants, toestimate an exposure dose, and to evaluate possible health effects. The recommendationhas been modified for clarity. As mentioned before, a child blood-lead exposure study isplanned and will include the sampling items you mention.
- page 39, Recommendation 4: A simple survey of fishermen could be conducted to estimate local consumption of suckers caught from the Big River.
A survey of fishermen would very likely provide some helpful information, but would do little to eliminate exposure.
- page 39, Recommendation 5: Water softeners have been shown to be effective at reducing lead concentrations at the tap to acceptable levels.
Water softeners are an alternative to lowering lead levels in drinking water but should notbe considered the only approach.
- Table 4: Presents a summary of the indoor dust (vacuum) sample results. There are nohealth criteria directly applicable to metal concentration in dust in homes and typically the resultswould be compared to a background data generated by sampling homes distant and upwind of thesite. After a statistical analysis comparing mean off-site (upwind) values to on-site values, itcould be determined if metals levels in indoor dust were attributable to releases from the tailingspiles or to naturally-occurring metals levels. In lieu of suitable background data, Table 4includes for reference ATSDR's soil comparison values. The use of health-based criteria derivedfor exposure to surface soils, which are based on incidental ingestion of soils, as a means ofevaluating potential risks associated with inhaling or incidentally ingesting indoor dust isinappropriate. Further, ATSDR reference values for ambient air are also listed in Table 4, withan explanation that no air measurements were taken in or around residences. Without air data, nological comparison with air criteria can be made and the inclusion of reference values for air in Table 4 is not meaningful.
The values were included because much of what was in the vacuum cleaners had been onfloors and in home air at one time, and babies eat a great deal of dirt from floors. Weagree, though, that dust and soil levels are not directly comparable, so the comparisonsvalues for soil have been removed to avoid any confusion by the public. The comparisonvalue for air has also been removed.
- Table 9:
- This table presents the results for lead and cadmium in biota tissue. Tabulated results for zincand copper are not presented although the text on page 6 states that "in 1982,...the US F&WSfound elevated residues of lead, cadmium, and zinc in every biological form examined,...." Also,page 29 indicates that elevated levels of copper were found in mussels. Amend Table 9 toinclude other metal results for comparison.
Lead and cadmium levels were provided from the 1982 US F&WS study to demonstratethat biota in the Big River is being contaminated by the different tailings piles for manymiles down stream. Only lead and cadmium are listed because they are the contaminantspresent at levels of concern and were listed in summary table form to facilitateunderstanding from the reader's perspective.
- EPA has established screening values (SVs) which are described in their Guidance forAssessing Chemical Contaminant Data for use in Fish Advisories (EPA, 1993). SVs are"concentrations of target analyses in fish or shellfish tissue that are of potential public healthconcern and that are used as standards against which levels of contamination in similar tissuecollected from the ambient environment can be compared. Exceeding these SVs should be takenas an indication that more intensive site-specific monitoring and/or evaluation of human healthrisk should be conducted." The SV for cadmium is 0.01 mg/kg. Assuming the results presentedin Table 9 are of edible tissue only, the red-horse and catfish appreciably exceed the SV atWashington State Park only. Furthermore, exceeding the SVs should only prompt additionalinvestigations into the actual frequency these fish are ingested by humans. Although SVs havenot been identified for lead, the same investigative philosophy should apply. Table 9 wouldbenefit from the addition of SVs as comparative values, as was done in Tables 2, 3, and 4.
Although SVs were not used in this case, background values are provided for biotacollected 16 miles upstream (Irondale). Further downstream, values observed increased,showing higher accumulations in samples collected in biota up to 60 miles downstreamfrom the site. Runoff from the different piles may contribute substantially to this effect. We feel that the fish advisory, which is intended to stop exposure from this source ofcontamination, is more important than an investigation of consumption practices at thistime; however, such an investigation would be interesting.
- Table 10: Consider deleting the dermal absorption as complete exposure route, since most metals are not readily absorbed through the skin.
Although there is a completed exposure pathway by dermal contact, we agree that themetals present are not readily absorbed through the skin and should not add to exposure. We have removed dermal contact as a significant route of exposure from Table 10 andfrom the text.
1. 1Note: The 15 ppb Action Level was developed for use with public water supplies and is notapplicable to a single sample collected from a private well. ATSDR does use this value as acomparison value when selecting a contaminant for further evaluation if exposure to lead isoccurring.