Response to Comments
ALLIED PAPER/PORTAGE CREEK/KALAMAZOO RIVER
KALAMAZOO, KALAMAZOO COUNTY, MICHIGAN
The Public Advisory Council (PAC) for the Kalamazoo River Area of Concern Remedial Action Plan (RAP) asked the Michigan Department of Community Health (MDCH) to evaluate the health hazard from the polychlorinated biphenyls (PCBs) present in the water and sediment of the Kalamazoo River. Following their review of the public health assessment (PHA) for Allied Corp. Kalamazoo Plant, Kalamazoo, Kalamazoo County, Michigan, CERCLIS No. MID006007306 (MDPH 1991), the PAC requested responses to specific questions regarding dermal contact with and incidental ingestion of water and sediments during recreational use of the river. There is no apparent health hazard associated with the PAC's specific concerns.
On August 30, 1990, the U.S. Environmental Protection Agency (U.S. EPA) listed the Allied Paper, Inc./Portage Creek/Kalamazoo River Superfund site (API/PC/KR) on the National Priorities List (NPL). The site extends from Cork Street above Bryant Mill Ponds on Portage Creek in Kalamazoo, Michigan, down Portage Creek about 3 miles to its confluence with the Kalamazoo River, and down the Kalamazoo River about 35 miles to the Allegan City Dam (Figure 1).
Concentrations of PCBs in surface soil, sediments, and surface water from the Kalamazoo River basin are summarized in Tables 1 through 5. The PCBs probably entered the river during past operations of several paper plants along its banks. Several paper companies whose plants might have contributed to the contamination at the API/PC/KR site (the potentially responsible parties or PRPs) have carried out studies to develop appropriate remediation plans for the contamination under U.S. EPA and Michigan Department of Environmental Quality (MDEQ) oversight (BBL 1994a-b, 1995, 1998, 2000a-b).
In December 1991, working under a cooperative agreement with the federal Agency for Toxic Substances and Disease Registry (ATSDR), the Michigan Department of Public Health (MDPH)(1) prepared a PHA for the API/PC/KR site (MDPH 1991). The PAC reviewed the PHA and, in 1997, requested MDCH to address further specific concerns regarding incidental ingestion of contaminated sediments and suspended solids and the completeness of the health effects database on which governmental agencies base their criteria for PCBs (Appendix A).
The MDEQ Generic Clean-up Criteria for Direct Contact with soil (DCC) identify a soil concentration that is protective against adverse health effects due to long-term ingestion and dermal exposure to contaminated soil. The DCC for PCBs are 4,000 ppb for residential use and 20,000 ppb for industrial use (MDEQ 2000b). ATSDR Comparison Values (CVs) are used to select contaminants of concern for further evaluation in ATSDR PHAs. The CVs for noncancer health effects from exposure to PCBs in soil are 1,000 ppb for a child and 10,000 ppb for an adult (ATSDR 2001). U.S. EPA, the U.S. Department of Health and Human Services, and the International Agency for Research on Cancer have stated that PCBs "are probable," "may reasonably be anticipated to be," and "are probably" human carcinogens, respectively (ATSDR 2000). The CV for a 1 in 1 million increased cancer risk over a lifetime exposure to PCBs is 400 ppb (ATSDR 2001). (A "significantly increased" risk of contracting cancer is generally considered to be such that, out of 10,000 to 1 million people who incur exposure to a chemical, one more person would develop cancer than would in a similar population that does not experience the exposure.)
Many of the concentrations found in the sediments and soils along Portage Creek and the Kalamazoo River (Tables 1 through 3) greatly exceed the DCC and CVs. However, the DCC and CVs are meant to protect people who would come into contact with PCB-containing soil every day around their homes or in their work places. However, the areas containing the exposed sediments along the river are not occupied by residences or businesses. For the residences along the east bank of Bryant Mill Ponds along Portage Creek with yards that abut exposed sediments, Allied Paper, Inc., one of the PRPs, constructed a fence in late 1990 separating those properties from the sediments (MDPH 1991). The 1999 aerial photos included in the draft Remedial Investigation Report - Phase 1 (BBL 2000a) do not show any residences similarly adjacent to exposed sediments in the other drained impoundments.
No one is likely to spend as much time in contact with the river sediments as is assumed in the calculation of the DCC or CV. Therefore, an ingestion intake rate was calculated on the basis of several assumptions made regarding recreational use of the river (Appendix B). An older child might be expected to be exposed to a maximum of 3.6E-6 mg (3.6 nanograms [ng]) of PCBs per kg of body weight per day, whereas a young child exhibiting pica behavior (abnormal consumption of soil and other nonfood items) might be expected to be exposed to 8.3E-5 mg (83 ng) of PCBs per kg of body weight per day, based on the highest surface sediment concentration found in the most recent sampling. The reference dose (RfD) of a chemical is an estimate, with safety factors built in, of the daily, lifetime exposure to that chemical that is not likely to cause adverse health effects. The RfD for PCBs is 2E-5 mg (20 ng) per kg of body weight per day and is based on ocular, glandular, and immunological effects seen in monkeys (U.S. EPA 1994). Although recent PCB studies have shown that the chemicals can act as endocrine disruptors and cause developmental delays, which are considered to be more critical effects, the dataset describing these results is not yet sufficient enough to justify changing the RfD.
The ingestion intake calculations discussed above show that an older child using the river recreationally would receive less than one-fifth of the RfD for PCBs in this scenario. There would be a concern that a child displaying pica behavior could consume an unsafe amount of PCBs. It should be noted, however, that the concentrations listed in Tables 1 through 3 are the maxima found at the time and place listed. While it is possible that someone using the river could be exposed only to sediments containing the high concentrations listed, it is more likely that the exposure would be to sediments containing a range of concentrations, averaging much lower than the peak value. Moist sediments might adhere more strongly to skin than drier soil, potentially increasing the amount of sediments incidentally ingested compared to dry soil. On the other hand, river water would tend to wash the sediments off before the soiled skin reaches the mouth or food.
Residents of the Kalamazoo River area have expressed concern about the potential for exposure to PCBs through the ingestion of sediments suspended in river water. Water taken from the Kalamazoo River from March through July 2000 contained up to 100 milligrams per liter (mg/L) total suspended solids (TSS), water from Portage Creek contained up to 140 mg/L TSS, and water from other tributaries to the Kalamazoo River contained up to 840 mg/L TSS (BBL 2000b). If the Kalamazoo River were used as a drinking water supply, the amount of TSS one might ingest in a day through drinking the water might be substantially higher than the amount of soil one would be likely to ingest via contact with sediments from the river. There are no known public water supply intakes on the Kalamazoo River, though there might be private intakes that are not on any official record. Except for the users of such private intakes, consumption of the river water is most likely to be incidental.
The Great Lakes Initiative, as used by the MDEQ Surface Water Quality Division (SWQD), bases its incidental ingestion rate of 10 ml/day based on an assumption of 123 hours of recreational exposure per year and an average mouthful of water (30 ml) per hour of recreation (Bush 2002). Assuming that the most recent maximum concentration of PCBs in sediment from the Kalamazoo River or Portage Creek (29,000 ppb in 2000) were used to estimate PCB intake from TSS ingested incidentally, a 15-kg toddler might ingest up to 1.62E-5 mg (16 ng) PCBs per kg body weight per day, an amount that is below the RfD, discussed earlier. It should also be noted that the very highest TSS concentrations were measured in water collected from tributaries to the river (Gun River, Schnable Brook) that drain rural areas. The elevated TSS concentrations might be due to erosion of upland soil from agricultural fields, especially during wet weather. Water from these tributaries contained no detectable PCBs (Table 4), though sediment from these tributaries has not been collected and analyzed (BBL 2000b). Therefore, exposure to PCBs in TSS is not expected to result in adverse health effects.
Concerns have also been raised regarding exposure to sediment that is resuspended by boats, waves, or people wading or swimming. The MDEQ-SWQD does not have empirical data nor is it aware of any studies examining resuspension in the river. However, based on anecdotal evidence, the major source of resuspension of bedded sediment would be wind-induced wave action in the impoundments along the river. Boat-induced waves seem to be fairly uncommon, except possibly in Lake Allegan. Rainstorms resulting in peak flows would cause eroded bank sediment to resuspend in the river (Rathbun 2002). While resuspension may occur, the previous discussion on TSS explains that exposure to sediments in this manner is not expected to result in adverse health effects.
In order to evaluate the potential for uptake of PCBs, there have been several studies of people who have come into contact with contaminated soil. In 1982, a Michigan Department of Natural Resources (MDNR)(2) investigation of soil contamination at the Barrels, Inc. site in Lansing, Michigan, found up to 10 million ppb of PCBs in the soil on the property (ATSDR 1988). At the MDNR's request, MDPH staff analyzed blood samples from 10 workers at the company, including those who had handled the barrels containing the PCBs. The workers' blood contained between 7 and 16 ppb PCBs, within the range of values found in numerous epidemiological studies of populations without occupational exposure to PCBs or exposed via consumption of fish from PCB-contaminated waters (Table 6) (MDCH 1997a).
In 1986, the MDPH learned that some residents of the Lakewood community of Kalamazoo collected worms for fishing bait from a closed paper company landfill where the soil was heavily contaminated with PCBs (up to 64,000 ppb). The MDPH analyzed samples of nine residents' blood, which contained serum PCB levels between nondetect and 14.1 ppb (median 5.1 ppb) (compare with Table 6) (MDCH 1997b).
In 1986, the MDPH became aware that children were playing in the alleys near the Carter Industrial NPL site in Detroit, a metal recycling operation where the soils were heavily contaminated with PCBs (up to 12 million ppb in ash on the site, up to 8.8 million ppb in sewer sediment from near the site [MDPH 1992]). While the U.S. EPA and the MDNR were cleaning up the contamination, MDPH tested the blood of 193 residents of the neighborhood. These samples contained up to 81 ppb PCBs, with a mean of 10.7 ppb (compare with Table 6) (MDPH 1987).
The Indiana State Department of Health (ISDH) has carried out two similar studies. A study in Bloomington, Indiana, where soil PCB concentrations ranged up to 9 million ppb, found mean serum PCB concentrations of 8.1 ppb for males, and 7.8 ppb for females, comparable to those in nonexposed populations (Table 6) (ISDH 1992). At the Shelly Ditch site in Crawfordsville, children who had been playing in soil or sediments containing from 200 to 384,000 ppb PCBs had serum PCB levels ranging from 3 to 9.3 ppb, with a mean of 3.4 ppb (ISDH 1997).
These studies indicate that people who are dermally exposed to very high soil concentrations of PCBs tend to accumulate very little of the chemicals in their bodies. On the other hand, people exposed occupationally to pure or technical-grade PCBs sometimes developed a skin disorder called chloracne when they came into contact with the chemicals (ATSDR 2000). At the much lower PCB concentrations found at most sites of environmental contamination, the chemicals tend to adhere to organic materials in the soil, which migrate through the skin less easily than pure PCBs or technical-grade PCB mixtures.
PCBs are present in the sediments and surface soils of the API/PC/KR site at concentrations above the MDEQ DCC. However, the most likely scenario for human exposure to the sediments–recreational use of the river–involves much less frequent exposure than in a home or workplace, so there is no need for restriction of access to the sediments. In addition, several studies of human exposure to PCB-contaminated soils have found that such exposure has not resulted in significant absorption of the chemical into the body. Therefore, no apparent public health hazard is posed by the contamination of the sediment.
Based on the PCB concentrations reported in the sediment and water of the Kalamazoo River, and considering the frequency of exposure to the sediments and limited absorption of PCBs from soils, there is no need to restrict access to the Kalamazoo River or Portage Creek. Fishermen should be apprised of the likelihood of PCB contamination of fish from the river, this information being available in the Michigan Fish Advisory.
ATSDR. 1988. Agency for Toxic Substances and Disease Registry. Preliminary Health Assessment for Barrels, Inc, Lansing, Michigan. September 30, 1988.
ATSDR. 1994. Agency for Toxic Substances and Disease Registry. Toxicological Profile for Chlorodibenzofurans. ATSDR/TP-93/04. May 1994.
ATSDR. 2000. Agency for Toxic Substances and Disease Registry. Toxicological Profile for Polychlorinated Biphenyls, Update. November 2000.
ATSDR. 2001. Agency for Toxic Substances and Disease Registry. Unpublished comparison values. Distributed December 21, 2001.
BBL. 1994a. Blasland, Bouck and Lee, Inc. Allied Paper, Inc./Portage Creek/Kalamazoo River Superfund Site, Remedial Investigation/Feasibility Study, Draft Technical Memorandum 10, Sediment Characterization/Geostatistical Pilot Study. April 1994.
BBL. 1994b. Blasland, Bouck and Lee, Inc. Allied Paper, Inc./Portage Creek/Kalamazoo River Superfund Site, Remedial Investigation/Feasibility Study, Draft Technical Memorandum 14, Biota Investigation. July 1994.
BBL. 1995. Blasland, Bouck and Lee, Inc. Allied Paper, Inc./Portage Creek/Kalamazoo River Superfund Site, Remedial Investigation/Feasibility Study, Draft Technical Memorandum 16, Surface Water Investigation. March 1995.
BBL. 1998. Blasland, Block and Lee. Allied Paper, Inc./Portage Creek/Kalamazoo River Superfund Site, Remedial Investigation/Feasibility Study, Draft Addendum 3 to Draft Technical Memorandum 14. 1998.
BBL. 2000a. Blasland, Block and Lee. Allied Paper, Inc./Portage Creek/Kalamazoo River Superfund Site, Remedial Investigation/Feasibility Study, Remedial Investigation - Phase I, Draft for State and Federal Review. October 2000.
BBL. 2000b. Blasland, Block and Lee. Supplement to the Kalamazoo River RI/FS - Phase I, Draft for State and Federal Review. October 2000.
Bush, D. 2002. Michigan Department of Environmental Quality, Surface Water Quality Division. Personal communication.
CDM. 2000. Camp Dresser and McKee. Final Human Health Risk Assessment, Allied Paper, Inc./Portage Creek/Kalamazoo River Superfund Site. August 18, 2000.
ISDH. 1992. Indiana State Department of Health. Final Report on Community Exposure to Polychlorinated Biphenyls, Bloomington, Indiana. June 1992.
ISDH. 1997. Indiana State Department of Health. Draft Health Consultation for Shelly Ditch, Crawfordsville, Indiana. June 16, 1997.
MDCH. 1997a. Michigan Department of Community Health. Files - Barrels, Inc.
MDCH. 1997b. Michigan Department of Community Health. Files - Lakewood Study.
MDCH. 2001. Michigan Department of Community Health. 2001 Michigan Fish Advisory. January 2001. At http://www.mdch.state.mi.us/pha/fish/index.htm
MDPH. 1987. Warner, S.C., Williams, D., MDPH, Center for Environmental Health Sciences. Health Effects of Residential Exposure to Polychlorinated Biphenyls: A Study of Two Detroit Neighborhoods, Final Report. nd (1987?).
MDPH. 1991. Michigan Department of Public Health, for ATSDR. Preliminary Health Assessment for Allied Corp Kalamazoo Plant, Kalamazoo, Kalamazoo County, Michigan, CERCLIS No. MID006007306. December 23, 1991.
MDPH. 1992. Michigan Department of Public Health, for ATSDR. Interim Preliminary Health Assessment for Carter Industrials, Incorporated, Detroit, Wayne County, Michigan, CERCLIS No. MID980274170. May 20, 1992.
Rathbun, J. 2002. Michigan Department of Environmental Quality, Surface Water Quality Division. Personal communication.
Michigan Department of Community Health
Christina Bush, Toxicologist
John Filpus, Environmental Engineer
Robin Freer, Resource Specialist
Linda Larsen, Principal Investigator
ATSDR Regional Representative
Regional Services, Region V
Office of the Assistant Administrator
ATSDR Technical Project Officer
Division of Health Assessment and Consultation
Superfund Site Assessment Branch
|Bryant Mill Ponds||1972||surface||368,700|
|PC - Alcott St.||1993||surface||2,100|
|PC - Stockbridge Ave.||1993||surface||1,200|
|PC - Lake St.||1972||surface||117,610|
|PC - Crosstown Pkwy.||1993||surface||75,000|
|PC - Vine St.||1976||surface||55,580|
|PC - Portage St.||1993||surface||2,100|
|PC - Michigan Ave.||1976||surface||500|
|KR - A-site to Portage Creek||1993||surface||86,000|
|KR - Paterson||1982||surface||57,000|
|KR - Mosel Ave.||1993||surface||4,200|
|KR - G Ave.||1993||surface||69,000|
|KR - at Spring Brook||1993||surface||1,300|
|KR - D Ave.||1976||surface||10,300|
|KR - B Ave.||1993||surface||710|
|KR - at Silver Creek||1993||surface||5,500|
|KR - Allegan County above M-89 at Plainwell||1993||surface||4,500|
|KR - 10th St.||1993||surface||4,100|
|KR - Plainwell Dam||1983||surface||55,900|
|KR - Otsego City Dam||1993||surface||94,000|
|KR - Farmer St.||1993||surface||41|
|KR - Otsego||1987||surface||120,000|
|KR - M-89 (at Otsego)||1976||surface||66,600|
|KR - Otsego Dam||1985||surface||57,000|
|KR - Trowbridge Dam||1983 (1)||surface||81,000|
|KR - 26th St.||1993||surface||2,700|
|KR - 26th St.||2000||14-18"||580|
|KR - Williams Rd.||1993||surface||3,200|
|KR - City of Allegan Dam||1993||surface||49,000|
|KR - M-118||1993||surface||280|
|KR - Allegan||1976||surface||24,670|
References: BBL 1994a, BBL 2000a, MDPH 1991
A Proceeding downstream. KR = Kalamazoo River, PC = Portage Creek
B Unless otherwise indicated, location only sampled once in a given year. (1) = first round, (2) = second round.
C Sediment sample was taken frozen.
|KR - A-site to Portage CreekB||surface||970|
|KR - Mosel Ave.||surface||560|
|KR - G Ave.||surface||1,300|
|KR - at Spring Brook||surface||1,400|
|KR - D Ave.||surface||2,200|
|KR - B Ave.||surface||5,100|
|KR - at Silver Creek||surface||5,800|
|KR - Allegan County above M-89 at Plainwell||surface||15,000|
|KR - Plainwell Dam||surface||29,000|
|KR -Otsego City Dam||surface||9,100|
|KR - Otsego Dam||surface||61,000|
|KR - Trowbridge Dam||surface||68,000|
|KR - 26th St.||surface||1,800|
|KR - Williams Rd.||surface||2,200|
|KR - City of Allegan Dam||surface||NDC|
Reference: BBL 2000a
A. Proceeding downstream. KR = Kalamazoo River
B. Includes exposed sediments in drained impoundments.
C. Not Detected (limit of detection = 61 ppb).
|KR - upstream of Battle Creek||1988||surface||NDB,C|
|KR - Comstock||1993||surface||NDD|
|KR - Sprinkle Rd.||1993||surface||75|
|PC - Monarch Mill Rd.||1984||surface||710|
|Kalamazoo River - Ottawa Marsh||1985||surface||1,400|
References: BBL 2000a, MDPH 1991
A. Proceeding downstream. KR = Kalamazoo River, PC = Portage Creek
B. ND = not detected
C. Limit of detection = 2,400 ppb
D. Limit of detection = 54 ppb
|KR - upstream of Morrow Pond||2000||NDB,C|
|KR - downstream of Morrow Pond Dam||1994||0.048|
|KR - Comstock||2000||0.0049|
|KR - below Allegan Dam||1985||0.152|
|Swan Creek Marsh||2000||NDC|
|KR - New Richmond||1982||0.079|
|KR - U.S. 31||1982||0.121|
|KR - Saugatuck||1971-2||0.065|
References: BBL 1995, BBL 2000b, MDPH 1991
A. Proceeding downstream. KR = Kalamazoo River
B. ND = not detected
C. Limit of detection = 0.0063 ppb
D. Limit of detection = 0.015 ppb
E. Limit of detection = 0.0062 ppb
|PC - Alcott St.||1985 (1)||0.283|
|PC - Michigan Ave.||1994||0.22|
|KR - Paterson Ave.||1985||0.042|
|KR - Mosel Ave.||1986||0.044|
|KR - D Ave.||1987||0.030|
|KR - 10th St.||1985||0.110|
|KR - Plainwell Dam||1985||0.062|
|KR - Farmer St.||1985||0.090|
|KR - Otsego Dam||1985||0.122|
|KR - 26th St.||1985||0.126|
|KR - Williams Rd.||1985||0.119|
|KR - M-118||1985||0.193|
|KR - Allegan||1994||0.052|
References: BBL 1995, BBL 2000b, MDPH 1991
A Proceeding downstream. KR = Kalamazoo River, PC = Portage Creek
B Unless otherwise indicated, location only sampled once in a given year. (1) = first round, (2) = second round, (3) = third round, (dr) = following dredging
|Area and sampling method||No. sampled||Year||PCB Level (ppb)|
|Without Occupational Exposure|
|Franklin, ID, volunteers||105||1979||--||< 5|
|Nonconsumers of Great Lakes sport fish||41||1996||1.2A||0.46-2.9|
|Females from Cornwall and Mississauga, Ontario, Canada (non-fish eaters)||35||1992||3.2B||1.3-12|
|Old Forge, PA, volunteers||138||1981||3.6||< 3-43|
|Males from Cornwall and Mississauga, Ontario, Canada (non-fish eaters)||45||1992||3.9B||1.1-12|
|Norwood, MA, volunteers||990||1983||4.9||2-30|
|Newton, KS, volunteers||7||1979||4.9||2-11|
|Jefferson, OH, volunteers||59||1983||5.8||1-45|
|Lake Michigan random non-fish eaters||418||1980||6.6B||< 3-60|
|Fairmont, WV, volunteers||40||1983||6.7||1-23|
|Canton, MA, volunteers||10||1980||7.1||1-18|
|Lake Michigan random non-fish eaters||29||1973||17.3||< 5-41|
|Bloomington, IN, volunteers and controls||110||1977||18.8||6-79|
|Consuming Fish from PCB-Contaminated Waters|
|Infrequent female consumers of Great Lakes sport caught fish||42||1994-95||0.9A||0.5-3.3|
|Infrequent male consumers of Great Lakes sport caught fish||57||1994-95||1.5A||0.5-9.7|
|Frequent female consumers of Great Lakes sport caught fish||187||1994-95||2.1A||0.7-58.2|
|Sport fishermen who ate fish from Lake Erie||11||1993||2.2A||1.2-3.2|
|Females from Cornwall and Mississauga, Ontario, Canada (fish eaters)||51||1992||3.4B||0.7-23.0|
|Frequent male consumers of Great Lakes sport caught fish||252||1994-95||4.8A||0.7-58.2|
|Males from Cornwall and Mississauga, Ontario, Canada (fish eaters)||101||1992||5.5B||0.9-21.0|
|Sport fishermen who ate fish from Lake Huron||11||1993||5.7A||1.3-12.9|
|Lake Michigan volunteer control eating < 6 lbs. sport fish annually||95||1989||6.8||2-42.1|
|Sport fishermen who ate fish from Lake Michigan||10||1993||8.6A||3.6-15.2|
|Lake Michigan volunteer sportfishers eating > 24 lbs sport fish annually||112||1989||19.A||4.9-173.8|
Reference: ATSDR 2000, Tables 6-21 and 6-28
A. Geometric Mean
The MDCH showed a draft of this consultation to the Kalamazoo River RAP PAC. Their comments and the MDCH responses to the comments are summarized below.
Comment: "Your example of 3 hours/week exposure (versus a 40 hour work week exposure scenario) concludes an exposure equivalent of 21,000 ppb, which exceeds all of the health effect Values (ranging from 40-10,000 ppb). River water washing sediments from the skin prior to ingestion (the explanation offered to negate risk associated with the scenario) while likely to happen sometimes, cannot account for all likely situations."
Response: Please accept our apologies, we did not realize when we wrote that passage that it could be easily interpreted backwards of our intent. The original intention was to derive a PCB concentration for the sediments that, under a 3 hour per week exposure, would result in the PCB dose that a worker would undergo while working on soil containing the 21,000 ppb MDEQ Clean-Up Criteria for Industrial and Commercial Use for 40 hours a week. Instead, in this document a likely dose per body weight was calculated for two scenarios and compared to the Reference Dose.
We agree that a person might sometimes transfer sediment from his or her hands to his mouth, but believe that it is less likely than in a soil-ingestion situation, thus reducing the likelihood of exposure below that assumed in the scenario used to develop the MDEQ Clean-Up Criteria.
Comment: "Neither does it address the concern of direct ingestion of sediments suspended in the water."
Response: A paragraph discussing this pathway of exposure has been added.
Comment: "In addition, the Values evaluated are specific to a relatively conservative number of health effects. Recent studies indicate that there are other effects for which there are no health effect Values (e.g. PCBs as 'endocrine disrupters' affecting the size of male genitalia; developmental delays). This is the state of the science for which no one need make excuses. However, since there are no promulgated Values for estimating these types of health effects risks, and because the concentrations of PCBs in Kalamazoo River and Portage Creek sediments exceed Values for better-known health effects that are probably less subtle, it seems bold to dismiss risks with assumptions that are arguably tenuous (last paragraph on page 3)."
Response: Discussion addressing this concern has been added to the text.
Comment: "Are there any studies estimating the volume of sediment resuspended by boats, waves or swimming children; the amount of water ingested by swimming children; or the health risks associated with the noted specific exposure pathway? If these data do exist, they should be included in the assessment. If they do not exist, perhaps the conclusion should be that there is insufficient information to adequately evaluate the health risks associated with the noted exposure pathway."
Response: A paragraph discussing this concern has been added.
The equation used to calculation the ingestion intake of PCBs in sediment is:
|[PCB]||= concentration of PCBs in sediment (ppm)|
|IR||= ingestion rate of soil (mg/d)|
|0.5||= bioavailability of PCBs|
|CF||= conversion factor (1 x 10-6)|
|EF||= exposure frequency (days/yr)|
|ED||= exposure duration (yrs)|
|BW||= body weight (kg)|
Two scenarios were calculated to determine potential ingestion intake rates of PCBs from the sediment of the Kalamazoo River or Portage Creek. For both scenarios, the maximum concentration found in the surface sediment in 2000, the year of the most recent samplings, was used: 29,000 ppb (29 ppm).
In the first scenario, an older child was assumed to use the river recreationally (e.g., fishing, wading). The child would visit the river from ages eight to 16, an exposure duration of eight years. The average body weight over that age span was assumed to be 50 kg (about 110 pounds). Assuming that the water is at a tolerable temperature for 180 days per year, an exposure frequency of 90 days/yr was used. The incidental ingestion rate of the sediment would be 50 mg/day. (The default value is 200 mg/day for a child up to six years and 100 mg/day through adulthood. It was assumed that the child will not spend the entire day exposed to the sediment, so one-quarter of the child default value was used.) The ingestion intake was calculated as follows:
In the second scenario, a young child exhibiting pica behavior was assumed to be the exposed individual. (Pica behavior is the abnormal consumption of soil and other non-food materials occasionally seen in children under five years of age.) The child would be brought to the river during its first five years of life (exposure duration) for an average of 25 days per year (exposure frequency). The U.S. EPA and MDEQ default weight for a child through six years of age is 15 kg. Again it was assumed that the child will not spend the entire day exposed to the sediment, so one-quarter of the pica intake rate of 5000 mg/day (1250 mg/day) was used. The ingestion intake was calculated as follows:
This Allied Paper/Portage Creek/Kalamazoo River Health Consultation was prepared by the Michigan Department of Community Health under a cooperative agreement with the Agency for Toxic Substances and Disease Registry (ATSDR). It is in accordance with approved methodology and procedures exisiting at the time the health consultation was begun.
Alan W. Yarbrough
Technical Project Officer, SPS, SSAB, DHAC, ATSDR
The Division of Health Assessment and Consultation, ATSDR, has reviewed this public health consultation and concurs with the findings.
Chief, State Program Section, SSAB, DHAC, ATSDR
1 On April 1, 1996, the Michigan Department of Public Health (MDPH) Division of Health Risk Assessment was absorbed into the newly-formed Michigan Department of Community Health and the MDPH Division of Water Supply was transferred to the MDEQ Division of Drinking Water and Radiological Protection.
2 As of October 1, 1995, the environmental protection and regulation functions of the Michigan Department of Natural Resources (MDNR) were transferred to the newly-formed Michigan Department of Environmental Quality (MDEQ).