PUBLIC HEALTH ASSESSMENT
VASQUEZ BOULEVARD AND I-70
DENVER, DENVER COUNTY, COLORADO
Click here to view Appendix E in PDF format (PDF, 89KB)
Click here to view Appendix F in PDF format (PDF, 288KB)
Click here to view Appendix G in PDF format (PDF, 258KB)
To evaluate exposure to arsenic in soil for children with soil-pica behavior, ATSDR used the following formula:
Estimated exposure dose in soil-pica children =
The concentration in soil is the estimated maximum discrete level of arsenic based on theformula y = 6.399x where x is the maximum composite level and y is the maximum, discretearsenic level (see Table 2 in the section Arsenic in the VBI70 Study Area.) ATSDR used a rangeof soil intakes for a soil-pica episode from 600 mg to 5,000 mg per day. The bioavailabilityfactor for soil from the VBI70 site is estimated to range from 40 to 60%, while the body weightof a 1-year-old Hispanic child is estimated to be 11 kg.(32) The exposure frequency ranged from 1day (a 1-time event) to 3 days out of 7, or 3/7. The term 1/1,000,000 is a conversion factor sothat units cancel correctly. Table H-1 shows the range of doses for a 1-year-old soil-pica child atthe property with the highest soil arsenic contamination based on Phase III data.
The following examples show a sample calculation to estimate the dose if a 1-year-oldsoil-pica child lives at the most highly contaminated yard and exhibits soil-pica behavior in a partof the yard with the highest arsenic contamination.
4748 mg arsenic/kg soil x 5,000 mg soil/day x 0.6 x 1 x 1/1,000,000 / 11 kg = 1.3 mg/kg/day
As can be seen from Table H-1, a wide range of arsenic doses are possible for a 1-time soil-picaepisode (0.1 mg/kg/day to 1.3 mg/kg/day) depending upon the amount of soil eaten and thebioavailability. The estimated doses are obviously lower should the child eat soil from a lesscontaminated part of the yard. A range of estimated arsenic doses is also possible for habitualsoil-pica episodes (0.05 to 0.57 mg/kg/day), again depending upon how much soil is eaten and the assumed frequency of 3 times per week.
| Soil Intake |
|1-Time Episode |
Estimated Arsenic Dose
|1-Time Episode |
Estimated Arsenic Dose
|3 Days per Week(33) |
Estimated Arsenic Dose
|3 Days per Week |
Estimated Arsenic Dose
As mentioned previously in the text, about 300 children live at the 650 or so properties that are aconcern should a soil-pica child eat 5,000 mg soil. Of these 200 children, about 12 to 60 childrenmight have a soil-pica episode some time during their preschool years.
Children with typical soil intake levels
ATSDR estimated the range of arsenic exposures for preschool children who live in the VBI70 studyarea and who have typical soil intakes. Most preschool children have soil intake levels that range from10 mg to over 200 mg each day. Recently, a study was reported concerning soil ingestion in preschoolchildren who live near a hazardous waste site in Anaconda, Montana. The results of this 1-week studyshowed an average soil ingestion rate of 31 mg soil each day. Ninety-five out of one hundred childrenhad an average soil intake below 141 mg each day, and the highest reported average soil-ingestion was219 mg each day. What is of additional note in this study was that the authors found a soil-pica childand estimated soil ingestion to be between 600 and 700 mg (Stanek and Calabrese 2000).
When evaluating soil ingestion in children, one should remember that most children ingest smallamounts of soil while a small group of children ingest larger amounts of soil. For the VBI70 site,ATSDR used 30 mg soil ingested per day to estimate arsenic exposure for the typical preschool childand 200 mg soil ingestion per day to estimate arsenic exposure for preschool children at the upper endof typical soil intake. In addition, ATSDR looked at exposures for 1-year-old children who weighed 11kilograms (approximately 25 pounds) as well as the average weight of a 1 to 6 year-old child (16.6kilograms or approximately 37 pounds). As children grow older their weight increases, which meansthat their exposure to contaminants in soil decreases based on body weight. Estimating exposure for allthese age groups gives a wide range of dose estimates within each age group and between age groups.
ATSDR used the same basic formula to estimate acute arsenic doses for children with typical soilintake levels using the following parameters:
- maximum and average arsenic level in the property;
- an exposure frequency of one because exposure occurs every day;
- soil intake levels of 30 mg/day and 200 mg/day; and
- body weights of 11 and 16.6 kg.
Table H-2 shows the estimated dose for a 1-time exposure to the maximum arsenic levels in soil todetermine if children with typical soil intake are at risk of acute effects from exposure to arsenic. While estimates for 16.6 kg children were conducted, only dose estimates for 11 kg children areprovided here.
From Table H-2, the 1-time estimated dose exceeds ATSDR's provisional, acute MRL only forchildren with soil intakes approaching 200 mg while children with soil intakes around 30 mg are belowATSDR's provisional acute MRL. Only those children with intakes around 200 mg a day, who live atproperties with average arsenic levels around 760 ppm, and who ingest soil from the mostcontaminated part of a yard have arsenic exposure that are likely to cause the transient effects ofnausea, vomiting, diarrhea, and facial swelling. Most children with typical soil intakes (about 30 mg a day) are not at risk for acute harmful effects.
|Arsenic Concentration in Soil |
|Soil Intake |
|Estimated Dose at 40% Bioavailability and 11 kg Body Weight |
|Estimated Dose at 60% Bioavailability and 11 kg Body Weight |
|Provisional Acute MRL |
Click here to view Appendix I in PDF format (PDF, 554KB)
- How a chemical enters a person's blood after the chemical has been swallowed, has come into contact with the skin, or has been breathed in.
- Acute Exposure:
- Contact with a chemical that happens once or only for a limited period of time. ATSDR defines acute exposures as those that might last up to 14 days.
- Additive Effect:
- A response to a chemical mixture, or combination of substances, that might be expected if the known effects of individual chemicals, seen at specific doses, were added together.
- Adverse Health Effect:
- A change in body function or the structures of cells that can lead to disease or health problems.
- The Agency for Toxic Substances and Disease Registry. ATSDR is a federal health agency in Atlanta, Georgia that deals with hazardous substance and waste site issues. ATSDR gives people information about harmful chemicals in their environment and tells people how to protect themselves from coming into contact with chemicals.
- Background Level:
- An average or expected amount of a chemical in a specific environment. Or, amounts of chemicals that occur naturally in a specific
- How much of a chemical enters a human's body from the environment, usually present as percent bioavailable or percent absorb. An example is the percent of chemical that is absorbed across the gut once ingested.
- A group of diseases which occur when cells in the body become abnormal and grow, or multiply, out of control
- Any substance shown to cause tumors or cancer in experimental studies.
- See Comprehensive Environmental Response, Compensation, and Liability Act.
- Chronic Exposure:
- A contact with a substance or chemical that happens over a long period of time. ATSDR considers exposures of more than one year to be chronic. EPA considers chronic exposure to from 10 percent of a lifetime to lifetime, for instance, from 7 to 70 years for humans.
- Completed Exposure Pathway:
- See Exposure Pathway.
- Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA):
- CERCLA was put into place in 1980. It is also known as Superfund. This act concerns releases of hazardous substances into the environment, and the cleanup of these substances and hazardous waste sites. ATSDR was created by this act and is responsible for looking into the health issues related to hazardous waste sites.
- A belief or worry that chemicals in the environment might cause harm to people.
- Concentration or Level:
- How much or the amount of a substance present in a certain amount of soil, water, air, or food.
- See Environmental Contaminant.
- Dermal Contact:
- A chemical getting onto your skin. (see Route of Exposure).
- The amount of a substance to which a person may be exposed, usually on a daily basis. Dose is often explained as "amount of substance(s) per body weight per day".
- Dose Response:
- The relationship between the amount of exposure (dose) and the change in body function or health that result.
- The amount of time (days, months, years) that a person is exposed to a chemical.
- Environmental Contaminant:
- A substance (chemical) that gets into a system (person, animal, or the environment) in amounts higher than that found in Background Level, or what would be expected.
- Environmental Media:
- Usually refers to the air, water, and soil in which chemicals of interest are found. Sometimes refers to the plants and animals that are eaten by humans. Environmental Media is the second part of an Exposure Pathway.
- U.S. Environmental Protection Agency (EPA):
- The federal agency that develops and enforces environmental laws to protect the environment and the public's health.
- The study of the different factors that determine how often, in how many people, and in which people will disease occur.
- Coming into contact with a chemical substance.(For the three ways people can come in contact with substances, see Route of Exposure.)
- Exposure Assessment:
- The process of finding the ways people come in contact with chemicals, how often and how long they come in contact with chemicals, and the amounts of chemicals with which they come in contact.
- Exposure Pathway:
- A description of the way that a chemical moves from its source (where it began) to where and how people can come into contact with (or get exposed to) the chemical.
ATSDR defines an exposure pathway as having 5 parts:
- Source of Contamination,
- Environmental Media and Transport Mechanism,
- Point of Exposure,
- Route of Exposure, and
- Receptor Population.
When all 5 parts of an exposure pathway are present, it is called a Completed Exposure Pathway. Each of these 5 terms is defined in this Glossary.
- How often a person is exposed to a chemical over time; for example, every day, once a week, twice a month.
- Hazardous Waste:
- Substances that have been released or thrown away into the environment and, under certain conditions, could be harmful to people who come into contact with them.
- Health Effect:
- ATSDR deals only with Adverse Health Effects (see definition in this Glossary).
- Indeterminate Public Health Hazard:
- The category is used in Public Health Assessment documents for sites where important information is lacking (missing or has not yet been gathered) about site-related chemical exposures.
- Swallowing something, as in eating or drinking. It is a way a chemical can enter your body (See Route of Exposure).
- Breathing. It is a way a chemical can enter your body (See Route of Exposure).
- Lowest Observed Adverse Effect Level. The lowest dose of a chemical in a study, or group of studies, that has caused harmful health effects in people or animals.
- Minimal Risk Level. An estimate of daily human exposure - by a specified route and length of time -- to a dose of chemical that is likely to be without a measurable risk of adverse, noncancerous effects. An MRL should not be used as a predictor of adverse health effects.
- The National Priorities List. (Which is part of Superfund.) A list kept by the U.S. Environmental Protection Agency (EPA) of the most serious, uncontrolled or abandoned hazardous waste sites in the country. An NPL site needs to be cleaned up or is being looked at to see if people can be exposed to chemicals from the site.
- No Observed Adverse Effect Level. The highest dose of a chemical in a study, or group of studies, that did not cause harmful health effects in people or animals.
- No Apparent Public Health Hazard:
- The category is used in ATSDR's Public Health Assessment documents for sites where exposure to site-related chemicals may have occurred in the past or is still occurring but the exposures are not at levels expected to cause adverse health effects.
- No Public Health Hazard:
- The category is used in ATSDR's Public Health Assessment documents for sites where there is evidence of an absence of exposure to site-related chemicals.
- Public Health Assessment. A report or document that looks at chemicals at a hazardous waste site and tells if people could be harmed from coming into contact with those chemicals. The PHA also tells if possible further public health actions are needed.
- A group of people living in a certain area; or the number of people in a certain area.
- Potentially Responsible Party. A company, government or person that is responsible for causing the pollution at a hazardous waste site. PRP's are expected to help pay for the clean up of a site.
- Public Health Assessment(s):
- See PHA.
- Public Health Hazard:
- The category is used in PHAs for sites that have certain physical features or evidence of chronic, site-related chemical exposure that could result in adverse health effects.
- Public Health Hazard Criteria:
- PHA categories given to a site which tell whether people could be harmed by conditions present at the site. Each are defined in the Glossary. The categories are:
- Urgent Public Health Hazard
- Public Health Hazard
- Indeterminate Public Health Hazard
- No Apparent Public Health Hazard
- No Public Health Hazard
- Reference Dose (RfD):
- An estimate, with safety factors (see safety factor) built in, of the daily, life-time exposure of human populations to a possible hazard that is not likely to cause harm to the person.
- Route of Exposure:
- The way a chemical can get into a person's body. There are three exposure routes:
- breathing (also called inhalation),
- eating or drinking (also called ingestion), and
- or getting something on the skin (also called dermal contact).
- Safety Factor:
- Also called Uncertainty Factor. When scientists don't have enough information to decide if an exposure will cause harm to people, they use "safety factors" and formulas in place of the information that is not known. These factors and formulas can help determine the amount of a chemical that is not likely to cause harm to people.
- The Superfund Amendments and Reauthorization Act in 1986 amended CERCLA and expanded the health-related responsibilities of ATSDR. CERCLA and SARA direct ATSDR to look into the health effects from chemical exposures at hazardous waste sites.
- Source (of Contamination):
- The place where a chemical comes from, such as a landfill, pond, creek, incinerator, tank, or drum. Contaminant source is the first part of an Exposure Pathway.
- Special Populations:
- People who may be more sensitive to chemical exposures because of certain factors such as age, a disease they already have, occupation, sex, or certain behaviors (like cigarette smoking). Children, pregnant women, and older people are often considered special populations.
- A branch of the math process of collecting, looking at, and summarizing data or information.
- Soil Ingestion:
- Soil ingestion is the consumption of soil. Soil ingestion may result from various behaviors including, but not limited to, mouthing, contacting dirty hands, eating dropped food, and consuming soil directly.
- Soil-pica is the recurrent ingestion of unusually high amounts of soil (i.e., on the order of 600 to 5,000 milligrams or more). While pica activity has a habitual component to the behavior, ATSDR is also concerned about 1-time soil ingestion events where unusually high amounts of soil are ingested. Groups at particular risk of soil-pica include children aged 6 years and younger and developmentally delayed individuals.
- Superfund Site:
- See NPL.
- A way to collect information or data from a group of people (population). Surveys can be done by phone, mail, or in person. ATSDR cannot do surveys of more than nine people without approval from the U.S. Department of Health and Human Services.
- Synergistic effect:
- A health effect from an exposure to more than one chemical, where one of the chemicals worsens the effect of another chemical. The combined effect of the chemicals acting together are greater than the effects of the chemicals acting by themselves.
- Harmful. Any substance or chemical can be toxic at a certain dose (amount). The dose is what determines the potential harm of a chemical and whether it would cause someone to get sick.
- The study of the harmful effects of chemicals on humans or animals.
- Uncertainty Factor:
- See Safety Factor.
- Urgent Public Health Hazard:
- This category is used in ATSDR's Public Health Assessment documents for sites that have certain physical features or evidence of short-term (less than 1 year), site-related chemical exposure that could result in adverse health effects and require quick intervention to stop people from being exposed.
March 24, 1999
Ms. Bonnie Lavelle, RPM
US EPA Region VIII
999 18th Street, Suite 500
Denver, CO 80202
Re: Community Concerns
Dear Ms. Lavelle:
As you know, the Agency for Toxic Substances and Disease Registry (ATSDR) has started activitiesassociated with its public health assessment of the Vasquez Boulevard site (VBI70). One of the majorcomponents of the public health assessment is to identify and address community health concerns. Todate, the VBI70 health team has met and conducted numerous conference calls with representativesfrom various neighborhood organizations around the site. The VBI70 health team consists ofrepresentatives from ATSDR, Colorado Department of Public Health and Environment, DenverDepartment of Environmental Health, and community representatives. Community representatives onthe VBI70 health team have told us many of their concerns.
As we discussed with you earlier, some concerns that the community representatives have expressedare outside of ATSDR's responsibilities in the Superfund process. We have informed the communityrepresentatives that when concerns come up that are more appropriately answered by other agencies,we will convey those concerns to the appropriate agency or organization.
Listed below are the concerns that have been raised that would best be answered by the EPA. Our responses to the community representatives on certain concerns are in italics.
- Community representatives expressed a need to understand the sampling methods the EPAused at the VBI70 site. Specifically, they want to understand the difference between acomposite versus an average, and how the difference between the two is used in riskassessment. Community representatives also want to know why the EPA did not samplefor cadmium and zinc.
- Community representatives want to know the reasons certain houses were deleted from the list of houses for an emergency cleanup?
- Community representatives want to know beforehand the meanings of environmental andhealth terms that might be used during work group discussions. During our discussionswith them, they did not specify any terms in particular, although I remember themmentioning MRLs and RfDs as examples during work group meetings.
- Community representatives expressed a need to better understand the EPA's riskassessment process. They also wish to have the explanation in writing.
ATSDR realizes that while some sampling was done for cadmium and zinc (for example,some of the confirmatory samples measured for cadmium and zinc), the communityrepresentatives did not understand the EPA's previous explanations.
We discussed with the community representatives the EPA's explanation and handoutgiven during the January 28 working group meeting. During our discussion with the community representatives, we realized that they had concerns about the selection ofproperties for removal activities and related topics. For instance, communityrepresentatives disagreed with the way houses were selected for sampling. Other issuesthat were raised included questions about the sampling approach, door-to-doorcanvassing, testing before action levels are set, and Phase III samples. We suggested tothe community representatives that they discuss the issues with you.
I think the community representatives understand the EPA's reasons for selecting homesfor removal activities but may still disagree with those reasons. In addition, they haveother concerns related to the selection of homes for removal as well as sampling andtiming issues. EPA staff members may want to talk to the community representativesagain about the issues mentioned to have a better understanding of their concerns andquestions.
I have agreed to put together a short dictionary of scientific terms that ATSDR might use. We are also passing the concern onto you since the EPA has its own scientific terms andjargon.
As we continue to receive concerns related to the EPA, we will forward them to you. Thank you foryour attention to these issues. If I can provide you with additional information, please contact me at(404) 639-0639.
David Mellard, Ph.D.
Division of Health Assessment and Consultation
Ms. Joan Hooker
Mr. Anthony Thomas
Ms. Sandy Douglas
Ms. Melissa Muñoz
Ms. Rosemary Riley
Ms. Lorraine Granado
Ms. Barbara O'Grady
Ms. Celia VanDerLoop
Ms. Susan Muza
Click here to view Appendix L in PDF format (PDF, 2237KB)
When ATSDR released the Public Health Assessment for the VBI70 Site in March 2002, theAgency provided a 6-week period for public comments to be submitted. The public commentperiod ended April 22, 2002. ATSDR received comments from several individuals during thisperiod and those comments along with ATSDR's response follow. When appropriate, ATSDRmade changes in the public health assessment. When changes were not made, ATSDR explainedthe reason.
- Comment: The recommendation for additional sampling of soil lead to the east and southeast of the existing study area needs to be supported since Figures 10 and 11 show the spatial distribution of lead increasing to the west and southwest, but declining to the east.
- Comment: The purpose of the study as outlined in the first paragraph on page 1 seems consistent with the broad exposure parameters addressed in the tables, figures, and charts in Appendix B; however, possible synergistic effects of the range of pollutants identified therein are never addressed in the body of the study, which focuses primarily on arsenic and lead.
- Comment: It seems that 1995 is the most recent source of data for the amount of chemicals released to air, water, and soil in zip code 80216. Why is the information 7 years old when the trend of 133% increase in six years appears to be so alarming? We know that XCEL Energy has begun reporting its Cherokee Plant emissions in the interim; however, since the Conoco-total Petroleum Refinery and Diamond-Shamrock border the study area but are outside the zip code of 80216, it is likely that other toxic emissions affect the study area. Perhaps for the purposes of the study, certain clearly significant emitters outside but bordering the zip code per se, should also be included.
- Comment: The PHA makes the following statement, "The estimated amount of exposure to adults and children from contact with soil is below ATSDR's chronic oral Minimal Risk Level (MRL) for cadmium and below EPA's chronic reference dose for cadmium." The commenter wants to know what these doses are and where can one find a table of them readily accessible to the public.
- Comment: It appears surface waters in and near the study area were sampled in 1997 (three samples from the South Platte River in a CDPHE study.) Were no samples of surface water collected from any source beside the South Platte River, which receives significant dilutary upstream waters? Perhaps sampling of storm drainage, ditch water, and surface puddles, at least, might be indicated to ascertain whether significant dissolved pollutants in groundwater may or may not be a concern.
- Comment: Has ATSDR done any investigation as to use of private wells in the study area?
- Comment: Missing from the list of CERCLIS, NPL, and RCRA facilities in Figure 9 are the following: G-K Services, a commercial dry cleaning facility (significant user of tetrachloroethane?) And Rocky Mounty Colby, a plastic pipe manufacturing plant, both located on Race Court; an electroplating facility in the Le Mouton business park on National Western Drive; a proposed new 22-acre asphalt batch plant at 5460 Franklin Street. Also: What of biogas emitters in the form of National By-Products, Denver Metro Wastewater Treatment, the sheep slaughterhouse on Washington Street, apparently commencing an expansion project, and Ralston Purina on I-70.
- Comment: From Figures 10, 11, and 12, it is apparent that there was a lead-arsenic soil sample taken at 5001 National Western Drive which is just within the blue line boundary of the survey area; however, it is not shown on the final results. Were other samples taken and not reported? If not, why were huge contiguous portions of the study area neglected entirely for sampling purposes?
- Comment: From Figure 20, there are at least 5 residents between 50th and railroad tracks, and not one as reported.
- Comment: I imagine the mobile sources emissions table is garnered from Denver Air Quality studies made primarily of auto and truck traffic. What is the methodology for ascertaining the numbers listed on the mobile emissions table C-1? If it is purely the VMT's associated with the intersecting Interstates and local arterials, are the diesel trains counted? Are the 'warm-up' times for the 4,871 diesel trucks registered in the zip code estimated? Is there a maximum baseline air quality exceedence date associated with this zip code that might reflect the 760,000 National Western Stock Show visitors, particularly the out-of-state diesel stock transport trucks converging on the area?
- Comment: Table C-3 apparently doesn't reflect accurately the TOTAL EMISSIONS: 80216 as titled, since Table C-1 registers 10,840 tons per day of mobile source emissions of CO, and Table C-3 lists 714.86 tons per year of carbon monoxide (CO). In the same vein, the other Mobile Emissions pollutants are vastly under-reported in Table C-3. PM-10 is reported but how about PM-2.5? Carbon dioxide and methane are heavy emissions in the zip code area, yet aren't calculated on the Table C-3 at all.
- Comment: Rocky Mountain Colby, the plastic pipe manufacturer, is not listed in Table C-4. The refineries (Conoco, Total Diamond Shamrock) are not listed.
- Comment: There are 6,706 people reported to live in the southwest Globeville, Elyria, Swansea demographic information. This same area contains apparently 4,871 registered diesel trucks; not counting what may be associated with the refineries, recycling, and waste management businesses. However, numerous freight trains also cris-cross the area on any given day and often idle for hours. We believe some number should be assigned to the impact of diesel rail traffic. In addition, numerous diesel trucks have destinations in the 80216 zip code although not being based here. It would be valuable to calculate the numbers of loading docks that get regular service in this zip code.
- Comment: Given the length of the document and its intended audience (the general public), we believe it is important that the summary of the PHA be concise and focuses on ATSDR's "take-home message". This is especially important since it is likely that most readers will read only the summary and, at most, skim portions of the rest of the document. After reading the summary, the reader should come away with a clear understanding of ATSDR's assessment of public health concerns for the site, and its recommendations for further action. It is our opinion that the summary does not clearly convey ATSDR's concerns in a manner readily accessible to the general public.
ATSDR Response: While it is true that lead contaminated-properties are more frequently found in the western portion of the VBI70 site, significant contamination can still be found in the eastern portion. Results from EPA's soil sampling of the VBI70 site show that the two neighborhoods that make up the eastern portion of the site (i.e., Swansea and Clayton) have 85 properties that exceed EPA's action level of 400 ppm. Preliminary soil samples further east of these neighborhoods in the Northeast Park Hill area found some properties with elevated soil lead levels. This information is now part of the public health assessment to justify sampling east and southeast of the VBI70 site.
ATSDR Response: ATSDR agrees and will revisit this issue in the public health assessment. Where possible, ATSDR will discuss what is known about the synergistic effects of arsenic and lead.
ATSDR Response: Using EPA's TRI website (http://www.epa.gov/tri) , ATSDR has updated the information about releases of chemicals to the environment in the 80216 zip code. ATSDR has also included information about chemical releases in other zip codes that are part of the VBI70 site (zip codes 80207 and 80205) and zip codes that border the 80216 zip code.
ATSDR response. ATSDR's chronic oral MRL for cadmium is 0.0002 milligrams cadmium per kilogram body weight per day (mg/kg/day). EPA's reference dose for cadmium is 0.001 mg/kg/day for exposures occurring from food (and 0.0005 mg/kg/day for exposures occurring from water.) ATSDR believes that if someone's intake of cadmium on a daily basis is less than 0.0002 mg/kg/day, then harmful effects from cadmium are not likely. A list of MRLs is available at the following ATSDR website: http://www.atsdr.cdc.gov/mrls.html. A list of EPA's reference doses can be found at this EPA website: http://www.epa.gov/iris/. This information has been added to the public health assessment.
ATSDR response: These issues were discussed in EPA's working group, which was made up of federal, state, and local environmental officials as well as community representatives from the VBI70 neighborhoods of Swansea, Cole, Clayton, Elyria, and southwest Globeville. In its recommendations to EPA, ATSDR recommended that EPA collect sediment samples from drainage ways (for instance, ditches) for the VBI70 site. The City and County of Denver collect water samples where streams empty into the South Platte River. Much of the analysis focuses on microbial levels but some samples measure for metals. In addition, ATSDR has learned that EPA collected sediment samples from the South Platte River as part of the ASARCO Globeville Superfund investigation. The results of these samples are discussed in response # 23.
As for possible contamination of groundwater beneath the VBI70 site, that seems unlikely because arsenic and lead are not migrating down through soil. Core soil samples showed that arsenic and lead were remaining at the surface and not migrating down through the soil; therefore, it is unlikely that groundwater beneath the site could be contaminated from VBI70 site contaminants. It should also be noted that Denver's drinking water comes from surface water reservoir and not from groundwater.
ATSDR response: ATSDR discussed this issue with community representatives as well as with federal, state, and local environmental officials. It appears that most people are on municipal water supplies and that private wells, if present, are used for gardening and watering lawns. Because groundwater beneath the site is not likely to be contaminated with arsenic and lead, this issue was not pursued further.
ATSDR response: ATSDR searched EPA's TRI, RCRA, and CERCLIS databases and none of the businesses mentioned in the previous comment report releases of chemicals to the environment. It may be that these businesses are not required to report releases. To ATSDR's knowledge, no information exists on the environmental impact from these businesses.
ATSDR response: EPA determined the areas to be sampled. As part of the VBI70 site investigation, EPA decided to collect soil samples from residential, recreational, and school areas in Elyria, Swansea, Cole, Clayton, and the southwest portion of Globeville. EPA originally did not include the southern portion of Cole and Clayton but extended their sampling strategy after recommendations from the community representatives. ATSDR reviewed all of these data and discussed them in the public health assessment. It should be noted that soil samples from the school and recreational areas were at safe levels except for one sample from nursery school. ATSDR discussed the significance of this sample in the public health assessment.
ATSDR has reviewed the residential and non-residential soil data provided to us by EPA. The data provided did not contain any soil samples from National Western Drive. It is unclear if a sample was taken from 5001 National Western Drive or if the data were not provided to ATSDR.
ATSDR agrees that portions of the VBI70 study have not been adequately characterized. For instance, EPA has not sampled the industrial areas in the VBI70 study. ATSDR has added a recommendation requesting EPA to sample those areas. ATSDR already recommended that EPA sample the remaining 1,000 residential properties that were not sampled as part of the recently completed investigation.
ATSDR response: Figure 20 is a population density map based on 1990 census. Even if the map were to be based on 1990 census, it would still have some uncertainty in the actual numbers. The map is intended as a guide to show the estimated number of people who live on the borders of the VBI70 study area. The purpose is to show the importance of collecting soil samples outside the VBI70 study area because the areas are highly populated. In response to the comment, ATSDR has added the word estimated to the title so that it now reads, "Estimated Population Density."
ATSDR response: Table C-1 was generated by the Colorado Department of Public Health and Environment (CDPHE), Air Pollution Control Division, in February 1999. It represents the results of running the EPA Mobile Source model. This model uses estimates of vehicle miles traveled, geometry of roads and arterials, and certain assumptions about the composition of the vehicle fleet (ages and types of vehicles) to generate estimates of air pollution emitted by vehicular traffic. The model does not consider diesel train emissions, or any "warm-up" times for the diesel trucks registered in the area. The model does not address local, short-term events such as the National Western Stock Show. The model is generally used for looking at compliance with carbon monoxide on a metropolitan-wide basis. The results listed here break out zip code 80216 as a single entity. The "vehicle miles traveled" number at the bottom of the table is for a year, within zip code 80216.
As pointed out by the commenter, the model probably underestimates to some degree the total emissions for zip code 80216. At this time, it is not possible to estimate the additional impact from these other emissions.
ATSDR response: Table C-3 is mislabeled, which has caused some confusion. We apologize for the inconvenience. This table represents total "Stationary Source" (factory) emissions in Zip Code 80216. This table was generated by the Colorado Air Pollution Control Division, using results from industries that are required to report emissions of hazardous air pollutants under Colorado Air Quality Regulation Number 3. Results here are for companies listing 80216 as their mailing zip code. Most of these companies are based in 80216, but the list may include some sources located elsewhere, who have headquarters in 80216. Similarly some sources in 80216, but not listing their headquarters here, may not be included. The title for Table C-3 has been corrected.
Table C-3 does not include any mobile sources (vehicular emissions), because it was generated from stationary source reports. Therefore, to obtain total emissions in the area, one would add Table C-1 results to those of Table C-3.
As the comment points out, PM10 (particulate matter 10 microns or less in diameter) is reported, but PM2.5 (particulate matter 2.5 microns or less in diameter) is not. PM2.5 is a subset of PM10, but has a separate national ambient air quality standard because its smaller size allows it to penetrate more deeply into the lungs. The EPA promulgated a standard for PM2.5 in July 1997. However, implementation of the standard was delayed for several years, until legal challenges could be resolved at the Supreme Court level. EPA has not yet developed "emission factors" for PM2.5. ("Emission factors" are estimates of PM2.5 emissions from smokestacks of the various industry types. Development of a full suite of emission factors takes some years, as it requires smokestack emissions tests at hundreds of industrial facilities). In the absence of "emission factors", Colorado has not yet required industries to report PM2.5 emissions. Therefore, the data needed to calculate PM2.5 emissions in zip code 80216 do not exist yet. Colorado does have a PM2.5 monitoring network. Although there is not a station in zip code 80216 specifically, results from nearby stations give some indication of what levels to expect. Thus far, Denver has not violated EPA's PM2.5 air quality standard.
The comment also asks about emissions of carbon dioxide and methane. Colorado Air Quality Regulation Number 3 requires industries to report emissions above a certain "threshold level" for specific compounds that are listed in the regulation. These compounds were listed based on their estimated toxicity. As carbon dioxide and methane are not considered highly toxic to humans, emissions are not reportable under Regulation 3. Therefore, there is no data that would allow the total emissions for 80216 to be estimated.
ATSDR response: Table C-4 is an ATSDR summary of information obtained from the Colorado Air Pollution Control Division. In 1999, the Division analyzed emitters of two regulated "groups" of toxic air pollution located in zip code 80216: volatile organic compounds (VOCs) and hazardous air pollutants (HP). The purpose was to determine which industrial groups (summarized by SIC - Standard Industrial Classification code) had the largest reported emissions. At that time, Rocky Mountain Colby (5125B Race Street, SIC Code 3084) reported 8.4 tons per year of volatile organic compounds. This put it below the "Top Ten" VOC emitters, so it is not included in the table.
As described in the response to comment eleven about Table C-3, the data in this table were produced by looking at the statewide list of stationary source emissions, and identifying facilities with the zip code 80216. The Colorado Air Pollution Control Division agrees that facilities located just outside of this zip code have emissions that affect air quality in the zip code 80216 area. The refineries are one example. Another is the Denver Metropolitan wastewater treatment plant.
ATSDR response: The total number of diesel trucks registered in zip code 80216 (Table C-5) is 4,871, which came from a Colorado Air Pollution Control database that lists fleets in 1999 that were registered in the state's diesel opacity self-inspection program. This program regulates "fleets", defined as 9 or more vehicles. Thus, businesses owning fewer than 9 vehicles are not counted in the total. As the comment points out, trucks from outside the area that make deliveries are also not counted. Additionally, trucks registered in the 80216 area may not actually be used in this area. Therefore, the number of "fleets" registered cannot be directly associated with emissions. The purpose of the table is to indicate that the area may have a disproportionate amount of diesel traffic.
The Colorado Air Pollution Control Division does not have data on train idling in the area, so emissions from this source cannot be readily estimated. The same is true for loading dock activity, which would be very time-consuming to survey. The Air Pollution Control Division believes that a better way to address concerns would be to measure emissions of semi-volatile organic compounds (SVOCs) in the area, and compare them to any health estimates available. (Many SVOCs are emitted from diesel vehicles). Volatile organic compounds, carbonyls, and metals were measured at Swansea Elementary (46th and Columbine) from July through December 2002. The Division is presently preparing a report summarizing these results. These data were collected under an EPA grant. Unfortunately, a companion grant application, requesting funds to operate a semi-volatile organic compound sampler was not funded. In fact, it has been a number of years since SVOCs were measured in Denver air. While PM2.5 measurements capture some of the diesel emissions component, the health effects of diesel emissions of SVOCs in Denver air cannot be estimated at this time. This is a serious gap in our current knowledge of air pollution levels in the area.
A member of the public reading this document might legitimately ask, "Does ATSDR believe that the levels of arsenic in my yard are of concern/" "Does ATSDR believe that the cleanup recommended by EPA will protect my health?" The document does not answer these questions. For example, after reading the summary, we understand that ATSDR is concerned about pica behavior in children at the site. For the pica scenario, ATSDR states that they are concerned about soil arsenic levels at 650 sampled properties, but does not provide the soil arsenic value that is the basis for this statement. A member of the public might ask "Which 650 properties?"
ATSDR response: ATSDR has reviewed the layout of the summary of the public health assessment and believes that the current headings provide the best method to convey the health messages for this site. Those headings include the following:
- Findings for arsenic in soil,
- Findings for lead in soil,
- Recommendations, and
- ATSDR's plans for the future
In addition, ATSDR will add to the Appendix the fact sheets that were developed for the public meetings in March 2002. These fact sheets cover all aspects of ATSDR's activities at the site and are in a easily readable format.
It is unclear why the commenter believes that a level of concern for arsenic and soil-pica is not identified in the summary. In the second paragraph under the heading "Findings for Arsenic in Soil" ATSDR makes the following statement: ".....EPA has identified properties as a concern for children with soil-pica behavior if the property has an average arsenic level in soil of 47 ppm or greater." ATSDR further explains that this means that about 650 properties are a concern and that 300 children might be at risk at these properties. ATSDR followed this concern up with individual letters to the residents describing the concern for either arsenic or lead in their property and held public meetings so that residents could talk to ATSDR staff members about their concerns.
Similar comments apply to ATSDR's discussion of long-term health effects for arsenic (i.e., cancer) and findings for lead. ATSDR mentions EPA's assessments for numbers of properties with a concern for long-term exposure to arsenic, but does not state whether or not ATSDR is in agreement with EPA's assessment. Also, ATSDR mentions EPA's range of soil values of concern for lead, but does not take a position on whether it agrees or disagrees with any part of the range of EPA values. If the document presents EPA's levels of concern, they should be presented in a fashion so the reader can understand whether or not ATSDR is in agreement with the values. The reader should be left with a clear message of ATSDR's concern for exposures to soil, at their property. If the document presents numbers of properties at which ATSDR has concern, it should also present the soil concentration from with the number was derived, such that an individual can verify whether ATSDR has concern regarding a specific property.
In numerous meetings with the community (e.g., ATSDR's health team meetings, EPA's working group meetings), ATSDR has raised issues around EPA's calculations for levels of health concern for arsenic and lead. After raising these issues in the community, it is incumbent on ATSDR to clearly express their findings, so the reader can reconcile ATSDR's previously expressed differences with EPA, and come to meaningful conclusions regarding ATSDR's public health concerns for the site.
ATSDR response: At the time the public health assessment was released in March 2002, EPA had discussed possible clean-up numbers with the members of EPA's working group but had made no final decisions. ATSDR officials were in the process of discussing with EPA the public health significance of those numbers. It should be known that ATSDR does not establish clean-up numbers at Superfund sites but rather works with EPA to evaluate the clean-up numbers EPA develops. This process was continuing when the public health assessment was being released. Because public health assessments can take long periods to go through several releases until a final release, other reports, such as, health consultations, are better suited to commenting officially on EPA's clean-up numbers at Superfund sites. Since March 2002, it should be noted that EPA has proposed to lower its clean-up numbers for arsenic in soil from 240 ppm to probably 70 ppm. The same has happened for lead, being lowered from 540 ppm to 400 ppm. ATSDR agrees that lowering these clean-up levels is protective of public health. Since these actions are not final, ATSDR will add these proposed new clean-up levels as a footnote to the public health assessment.
ATSDR response: It is important to realize that ATSDR's public health assessment is not like an EPA risk assessment, where EPA lays out all the calculations so someone can do those calculations if they wished. ATSDR's public health assessment describes the Agency's opinion about the public health significance of contaminated properties and describes which adverse health effects might be possible in an exposed population.
It should be pointed out that a footnote appears with the discussion that provides the intake rates that ATSDR used to estimate the site-specific dose when making decisions about the possibility of cancer. It should also be pointed out that ATSDR worked very closely with community representatives so they understand how ATSDR estimated doses and made public health decisions. In fact, community representative repeatedly thanked ATSDR for being clear in its explanation of these rather complex dose estimation and explanations.
ATSDR response: The purpose of the statement is to ally fears that people might have about arsenic in soil when they live on a property that is not contaminated. As requested by the commenter, ATSDR has added text that there is no risk to individuals with typical soil intake at many of the properties.
ATSDR response: EPA initially identified 240 ppm (i.e., mg/kg) as their clean-up for arsenic at the VBI70 site, probably sometime in late 2000 or early 2001. As comments and objections from members of EPA's workgroup for the VBI70 site continued, EPA lowered the clean-up level to 128 ppm arsenic in soil just prior to the release of the public health assessment. ATSDR verified this new clean-up level in numerous conversations with EPA. Since the release of the public health assessment, EPA has lowered the clean-up level for arsenic again, this time proposing 70 ppm arsenic in soil. ATSDR will add a footnote to the public health assessment about the new proposed clean-up level of 70 ppm. Because this newly proposed clean-up level for arsenic of 70 ppm has not been officially adopted by EPA, ATSDR will keep the original proposed number (i.e., 128 ppm) in the public health assessment and add a footnote to explain the newly proposed clean-up level of 70 ppm.
ATSDR response. Thank you for catching this oversight.
Point 1. As mentioned previously, since the public release of the PHA for the VBI70 site, EPA has proposed a lowered clean-up for arsenic, that is, 70 ppm as an average arsenic level in surface soil. This proposed action level is not final. ATSDR has added text at the appropriate places in the public health assessment to reflect EPA's evolving clean-up level for the VBI70 site. Since it is not final, the proposed clean-up level may change again.
Point 2. It is inappropriate for ATSDR to debate in a public health assessment EPA's quantitative cancer risk estimates from exposure to arsenic in soil. ATSDR has had numerous meetings with EPA to point out where EPA could be more conservative in its risk estimates and thus be more conservative in protecting public health. As it stands now, EPA is considering a clean-up level of 70 ppm for arsenic in soil, the same level that was used at the Globeville ASARCO site the commenter is referring to.
ATSDR response: ATSDR agrees about mentioning the limitation of having a sample size of 8. What is striking about the linear regression of the data from these 8 properties is the r2 value of 0.95. Such as high correlation coefficient points to the validity of the relationship between average arsenic level in a yard and the estimated maximum level.
At this point in the investigation, it is not necessary to describe EPA's method for estimating the maximum arsenic level in a yard.
ATSDR response: ATSDR has deleted the sentence.
ATSDR response: The referenced EnviroGroup report is EPA's draft technical memorandum for the Omaha and Grant Smelter, which is operable unit 2 for the VBI70 Superfund site. The memorandum provides information about the smelter, such as site description and history, along with information about surface water and groundwater hydrology. Very limited information is available about surface soil contamination on-site and migration of contaminants from the site to off-site areas. The memorandum does not contain or provide information about surface water run off from the five affected neighborhoods (i.e., Elyria, Cole, Clayton, Swansea, or southwest Globeville.) Therefore, it is not possible to evaluate the extent that lead and arsenic migration might be migrating from the residential properties in the VBI70 study area because environmental data have not been collected from surface drainage ways in the neighborhoods. Some information about contaminants in sediments from the South Platte River are available from the City and County of Denver, and ATSDR has requested this information. Information about arsenic and lead levels in sediment from South Platte River based on investigations at the ASARCO Globe Superfund Site have been added to the public health assessment.
ATSDR response: The Colorado Department of Transportation (CDOT) conducted limited air monitoring while doing road construction in the VBI70 area (CDOT 2000). CDOT conducted air monitoring from January 2001 to April 2003 and measured the impact of local road construction on PM10, arsenic, and lead levels in outdoor air. A final report from CDOT is expected in 2003. For more information, please contact the CDOT at CDOT Region 6, 2000 South Holly Street, Denver, Colorado 80222.
In August 2000, CDOT released a report entitled, "Air Quality Data Report, I-70 and Brighton Boulevard Interchange Modifications, April to June 2000." The purpose of the report was to assess the impact of dust (particulate matter), arsenic, and lead on local air pollution from dirt moving activity associated with road construction in the I-70 and Brighton Boulevard area. The report contains air quality information on air samples collected from April through June 2000.
Three air monitoring stations were located in Elyria, the neighborhood where CDOT was conducting road construction activity. The locations are (1) Brighton Boulevard and 44th Street, (2) 47th Street, parking lot of National Western Stock Show, and (3) High Street and 48th Avenue. Only 1 station measured PM10 (particulate matter less than 10 microns) while the other two stations measured total suspended particulates. Twenty-four hour air samples were collected every 3rd day and reported as a 24-hour average.
In April, May, and June 2000, none of the PM10 levels exceeded EPA's 24-hour standard of 150 micrograms per cubic meter (µg/m3). The average PM10 levels for April to June was 66 µg/m3 with the highest level detected being 126 µg/m3. Yearly average PM10 levels should be available in the soon to be released report covering air monitoring data from 2001 to 2003.
In April 2000, 24-hour arsenic levels were usually below the detection limit of the instrument but on three occasions 24-hour arsenic levels were found to be 0.003, 0.004, or 0.005 µg/m3. Two of these 24-hour air samples were in May and one was in June. If these 24-hour arsenic levels in air were to be averaged over the entire month, exposure levels would be significantly lower. The detected arsenic levels, however, do show that road work probably causes some resuspension of arsenic in soil.
Air monitoring results for lead show that 24-hour lead levels remain fairly constant with levels ranging from 0.025 to 0.047 µg/m3. Only one air sample showed a spike of lead levels in air at 0.5 µg/m3. The 24-hr lead levels from the three locations well below EPA's National Ambient Air Quality Standard of 1.5 µg/m3.
At least for the months covered by this report (April to June), there does not appear to be a health concern from CDOT's dirt-moving activity from road construction. It is important to realize, however, that these air three monitoring locations depict air quality in Elyria close to CDOT's activities and may not be indicative of air quality in the other four neighborhoods.
ATSDR response: Arsenic and lead will not evaporate from soil in its present form. While arsenic and lead bound to dust can enter the home in many ways (e.g., through open doors and windows and through air intake vents), ATSDR agrees that the exposure via crawlspaces are relatively minor. The discussion about crawlspaces has been deleted from the public health assessment.
ATSDR response: The dose estimates for soil-pica children with habitual soil-pica behavior is shown in Appendix H, Table H-1. The estimated dose for a habitual soil-pica child who lives in a yard with an average arsenic level in soil of 270 ppm is about 0.02 mg/kg/day, a level 10 times lower than the level known to cause serious effects (see reference to Armstrong et al., 1994 in the PHA.)
ATSDR response: The discussion of cancer and comparison to doses reported in the literatures already references ATSDR's Toxicological Profile for Arsenic, which summarizes the studies being cited. The studies can be found in Table 2-3, pages 77 and 78 in the profile. The estimated lifetime dose at 300 ppm arsenic in soil is 0.00045 mg/kg/day, a dose that is ½ the dose known to cause cancer in humans.
ATSDR response: The VBI70 public health assessment was reviewed by staff members from CDPHE and no comments were received from the State concerning the description of the State's blood lead program. To avoid confusion, ATSDR has deleted the phrase "state-wide" from its description of the State's blood lead program. ATSDR has provided contact information for the State's blood lead program in numerous locations in the public health assessment should someone need more specific information.
ATSDR response: There is clear evidence from the scientific literature that blood lead levels in 1- and 2-year-old children are related (in part) to soil lead levels in their yards. Since CDPHE is currently analyzing the results of blood lead levels in children who live in the VBI70 study area, it is more appropriate to wait for those results than to report information about blood lead levels that were not designed to assess the association of blood lead and soil lead.
ATSDR response: A brief explanation has been added to the text of the public health assessment.
ATSDR response: A footnote has been added to Table H-1 to explain the difference in a 1-time dose and a weekly dose and that different scientific reports are used to evaluate the significance of those estimated doses.
ATSDR response: ATSDR is unaware where the statement was made that there is very little concern. ATSDR has classified the VBI70 site a public health hazard at yards with elevated levels of arsenic or lead or both. This conclusion, however, does not apply to every yard and ATSDR has sent letters to residents whose yard is a concern. ATSDR has published a pictorial fact sheet letting people know what they can do to reduce their exposure to arsenic or lead in soil if their yard is contaminated. This educational effort, however, is not intended to replace clean up but rather is intended as a short measure that people can do to protect their health until EPA can remediate contaminated yards.
ATSDR response: At most of the properties, the arsenic and lead levels in soil are safe for workers. The public health assessment points out, however, that at some of the most contaminated properties, some workers might experience gastrointestinal upset (e.g., nausea, stomach ache) if they accidentally swallow large amounts of soil clinging to their hands or to food. Workers should wear gloves while digging on contaminated properties and should wash their hands before eating.
ATSDR response: The EPA plans to hold several meetings the VBI70 study area to announce its activities. Attending these meetings should allow you to ask EPA about ATSDR's recommendations. You can also contact the community representatives for the neighborhoods in the VBI70 study. They are listed in Appendix A.
ATSDR response: It is true that municipalities are required to maintain lead levels below EPA's Action Level for lead. That requirement means that water entering the distribution system must be below EPA's action level. However, drinking water can become contaminated with lead in the distribution system. The most likely place for this to happen is in the pipes at someone's house, particularly if the pipes are old and lead solder was used to seal the joints. The public health assessment did not discuss the possibility of the city's drinking water being contaminated with arsenic. It is not likely.
32 EPA conducted a study in pigs to determine the bioavailability of arsenic in soils from the VBI70 site. Five groups of pigs were fed soils with known amounts of arsenic from 5 yards from VBI70 site. Tests were conducted to determine how much arsenic actually crossed the pig's gastrointestinaltract. EPA determined that about 40% of the arsenic got into the pig. Some problems exist, however, with this pig study, most notably, pigs from the control group from 1 week of the 2 week study were lost to the study because of a mistake in dosing. Also, only 5 properties were tested. Therefore, ATSDR also used an upper estimate of 60% bioavailability. This percentage bioavailability was used because it is thehighest estimate of arsenic bioavailability from pig studies.
33 The weekly dose estimate is lower than the 1-time dose estimate because a child with soil-pica behavior is assumed to eat dirt only 3 days out of 7 days. Therefore, the dose is average over the a week by multiplying the dose by 3/7. Much is known about arsenic toxicity from acute poisoning so that different scientific reports are used to evaluate possible health effects from 1-time arsenic exposures and from weekly arsenic exposures.