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HEALTH CONSULTATION

Response to Public Comments

TEN MILE/LANGE/REVERE DRAINAGE SYSTEM
(a/k/a TEN MILE DRAINAGE SYSTEM PCB SPILL)
ST. CLAIR SHORES, MACOMB COUNTY, MICHIGAN


Table 1. PCB Concentrations Found in Water Samples Taken from the Ten Mile/Lange/Revere Drainage SystemA

Chemical of Interest MDEQ Generic GCC Adjusted GCCB Storm Water Sewer Catch Basin Sanitary Sewer Canal Wahby Pond
n Range n Range n Range n Range n Range
Total PCBs 3.3 0.1 55 ND-510 17 0.61-12.5 10 ND-4.1 6 ND-5.8 1 52
Arsenic 4,300 NA 55 ND-46 17 ND-5.8 10 ND-11 6 ND 0 NT
Barium 14,000,000 18,355 55 20-970 17 10-90 10 40-170 6 18-26 0 NT
Cadmium 190,000 NA 55 ND-6.3 17 ND-0.85 10 ND-3.5 6 ND 0 NT
Chromium 460,000C NA 55 ND-75 17 ND-15 10 ND-26 6 ND 0 NT
Lead ID ID 55 ND-270 17 ND-57 10 7.6-27 6 ND-9.3 0 NT
Mercury 56 NA 55 ND-0.54 17 ND-0.7 10 ND-0.34 6 ND 0 NT
Selenium 970,000 NA 55 ND-28 17 ND-7.3 10 ND-7.2 6 ND 0 NT
Silver 1,500,000 NA 55 ND-0.66 17 ND-0.9 10 ND-0.71 6 ND 0 NT

Reference: MDEQ 2002, Tetra Tech EMI 2002

GCC Groundwater Contact Criteria
ID insufficient data
n number of samples
NA not applicable for this scenario
ND not detected
NT sample not tested for chemical

Notes:  
A Concentrations in parts per billion (ppb)
B The MDEQ GCC protects workers in subsurface excavations from adverse health effects that can result from coming into dermal (skin) contact with a hazardous substance. It may be adjusted to address the protection of residents who may come into contact with contaminated surface water, such as swimming in a lake. (See Appendix E.)
C More protective criterion for chromium (VI) used


Table 2. PCB Concentrations Found in Sediment Samples Taken from the Ten Mile/Lange/Revere Drainage SystemA

Chemical of Interest Industrial DCC Storm Water Sewer Catch Basin Sanitary Sewer
n Range n Range n Range
Total PCBs 1 33 ND-121,000 14 0.02-28.5 2 3.9-48
Arsenic 61 33 ND-15 14 1.4-5.5 2 3.9-10
Barium 250,000 33 17-810 14 20-74 2 100-380
Cadmium 4,100 33 ND-20 14 ND-2.3 2 0.36-8.7
Chromium 17,000B 33 9.4-92 14 8.4-140 2 36-74
Lead 900 33 10-990 14 6.3-410 2 51-100
Mercury 1,100 33 ND-0.48 14 ND-1 2 ND-0.3
Selenium 18,000 33 ND-3.1 14 ND-1.1 2 0.45-0.54
Silver 17,000 33 ND-1.1 14 ND-0.4 2 0.1-0.3

Reference: MDEQ 2002, Tetra Tech EMI 2002

DCC Direct Contact Criteria
n number of samples
ND not detected

Notes:  
A Concentrations in parts per million (ppm)
B More protective criterion for chromium (VI) used


Table 3. PCB Concentrations Found in Sediment Samples Taken at Varying Depths from the Lange/Revere CanalA

Chemical of Interest Generic Residential DCC Adjusted DCCB 0-6" 6-12" 12-18" 18-24"
n Range n Range n Range n Range
Total PCBs 1 7 33 1.4-150 31 ND-4,900 12 0.36-140 5 1.5-140
Arsenic 7.6 83 33 ND-15 31 3.5-18 12 2.4-14 5 2.5-16
Barium 37,000 NA 33 23-170 31 31-250 12 50-170 5 35-150
Cadmium 550 NA 33 0.38-8.6 31 0.8-8.7 12 0.4-6.2 5 0.39-6.0
Chromium 2,500C NA 33 6.6-110 31 12-100 12 9.9-80 5 12-75
Lead 440 See note D 33 28-560 31 64-930 12 34-1,400 5 44-1,200
Mercury 160 NA 33 ND-3.3 31 ND-1.5 12 ND-1.4 5 ND-0.64
Selenium 2,600 NA 33 ND 31 ND-3.1 12 ND-1.5 5 ND
Silver 2,500 NA 33 ND-2.9 31 0.11-3.3 12 ND-1.8 5 ND-1.3

Reference: Tetra Tech EMI 2002

n number of samples
NA not applicable for this scenario
ND not detected

Notes:  
A Concentrations in parts per million (ppm)
B The MDEQ Residential DCC protects against adverse health effects due to long-term ingestion of and dermal exposure to contaminated soil. It may be adjusted to address the protection of residents who may come into contact with contaminated sediments, such as standing in the Lange/Revere Canal. (See Appendix F.)
C More protective criterion for chromium (VI) used
D IEUBK model does not easily allow for adjustment of the DCC for lead


Table 4. PCB Amounts Found in Wipe Samples Taken from the Ten Mile/Lange/Revere Drainage SystemA

Chemical of Interest Storm Water Sewer Catch Basin Sanitary Sewer
n Range n Range n Range
Total PCBs 28 ND-480 6 2.28-158 17 ND-189
Arsenic 0 NT 0 NT 0 NT
Barium 0 NT 0 NT 0 NT
Cadmium 0 NT 0 NT 0 NT
Chromium 0 NT 0 NT 0 NT
Lead 0 NT 0 NT 0 NT
Mercury 0 NT 0 NT 0 NT
Selenium 0 NT 0 NT 0 NT
Silver 0 NT 0 NT 0 NT

Reference: Tetra Tech EMI 2002

n number of samples
ND not detected
NT sample not tested for chemical

Notes:  
A Amounts in micrograms (µg)


Area Map
Figure 1. Area Map

Site Map
Figure 2. Site Map


APPENDIX A: "ST. CLAIR SHORES AREA RESIDENTS UNITING TO ADDRESS PCB CONTAMINATION; CITIZEN ORGANIZED PUBLIC FORUM ANNOUNCED" (ON-LINE NEWS RELEASE)

Click here to view Appendix A in PDF format (PDF, 37KB)


APPENDIX B: INSIDE ST. CLAIR SHORES "PCB INFORMATION AND INVESTIGATION: JUST THE FACTS ON THE 10-MILE DRAINAGE DISTRICT," MAY/JUNE 2002

Click here to view Appendix B in PDF format (PDF, 842KB)


APPENDIX C: THE CITY OF ST. CLAIR SHORES "JUST THE FACTS PCB INVESTIGATION UPDATE," VOLUME 1, ISSUE 3 - MAY 2002 (LETTER TO RESIDENTS)

Click here to view Appendix C in PDF format (PDF, 1,029KB)


APPENDIX D: INSIDE ST. CLAIR SHORES "PCB INFORMATION AND INVESTIGATION: JUST THE FACTS ON THE 10-MILE DRAINAGE DISTRICT," JULY/AUGUST 2002

Click here to view Appendix D in PDF format (PDF, 154KB)


APPENDIX E: ADJUSTMENT OF MDEQ GROUNDWATER CONTACT CRITERIA TO ADDRESS CHILDREN SWIMMING IN THE LANGE/REVERE CANAL

The purpose of the MDEQ Groundwater Contact Criteria (GCC) is to protect workers in subsurface excavations from adverse health effects that can result from coming into dermal (skin) contact with a hazardous substance. The GCC is protective of only chronic, not acute, effects, and it addresses only dermal exposure, not incidental ingestion nor inhalation of any volatiles. The GCC may be adjusted to address the protection of residents who may come into contact with contaminated surface water, such as swimming in a lake. This exercise will demonstrate how the criteria were adjusted to account for children, ages 9 to 12, swimming in the Canal. Adjusted criteria for carcinogenic and noncarcinogenic effects are calculated and compared.

PCBs are probable carcinogens (EPA 1997b). The equation used to determine the GCC of a known or probable carcinogen is below (MDEQ 2001b):

GCC sub carcinogen equals BW times AT times TR times CF sub 1 divided by SF times SA times SP times EV times EF times ED times CF sub 2

BW is the body weight. The range of body weights for a child of either sex, aged 9 to 12 years, is 31.5 to 45.3 kilograms (kg; EPA 2000). To be protective, the lower weight is used.

AT is the averaging time factor, which, for carcinogens, is equivalent to the average human lifespan of 70 years, or 25,550 days. When a chemical is found to be carcinogenic in laboratory animals, the research typically involves a high dose of the chemical given to the animal over a short period of time. Based on the assumption that a high dose of a carcinogen received over a short period of time is equivalent to a corresponding low dose spread over a lifetime, human exposures are calculated by prorating the total cumulative dose over an average person's lifetime.

TR is the target cancer risk, or the acceptable risk. An "acceptable" risk may range from one in ten thousand to one in one million, meaning that no more than one additional person in ten thousand (1E-4) or one million (1E-6) persons who are exposed to a carcinogen will die from cancer compared to a similar population not exposed to the carcinogen. The target risk in this exercise is set at one in one hundred thousand (1E-5).

CF1 is the first conversion factor used so that the appropriate units appear in the product of the equation. This factor is equal to one thousand micrograms per milligram (1E+3 µg/mg).

SF is the oral cancer slope factor, which is an estimate of the increased cancer risk from a lifetime exposure to a chemical. It is a probability estimate that is used only for comparative purposes. It is not a predictive tool. PCBs have been assigned varying slope factors based on level of exposure-specific risk and persistence. The slope factor chosen for this exercise is 2 per milligram per kilogram-day [2 (mg/kg-d)-1]. It reflects high risk and biological persistence (EPA 1997b) and is the most protective value to use.

SA is the skin surface area. For a child of either sex between the ages of 9 and 12 years, the average total skin surface area is 1.16 square meters (m2) or 11,600 square centimeters (cm2; EPA 2000).

SP is the skin penetration per event factor and based on the rate at which a specific chemical penetrates the skin and the exposure time, which is assumed to be 2 hours per event. The SP for PCBs is 1.95 cm/event (2002, J. Crum, MDEQ Environmental Response Division, personal communication).

EV is event frequency, or the frequency of contact with the contaminated water. It is assumed to be 1 two-hour event per day.

EF is exposure frequency. It is assumed in this exercise that a 9- to 12-year-old would swim in the Canal five days per week for 12 weeks (three summer months) for a total of 60 days per year. This scenario allows for bad weather and days spent away from the Canal. It may overestimate the frequency of exposure but it provides a protective estimate.

ED is exposure duration. It is assumed that the scenario will occur over three years, from age 9 to 12 years. Parents would likely have more control over where younger children would swim, and as a child enters adolescence, he or she might be more apt to use a community pool or beach as a social gathering place as well as for swimming.

CF2 is the second conversion factor used so that the appropriate units appear in the product of the equation. This factor is equal to 1 milliliter per square centimeter (1E-3 L/cm2).

The adjusted GCC for the carcinogenic effects of PCBs is calculated as follows:

Adjusted GCC sub PCBs (cancer) equals 31.5 times 25,550 times 1E minus 5 times 1Eplus 3 divided by 2 times 11,600 times 1.95 times 1 times 60 times 3 times 1E minus 3

AdjustedGCCPCBs(cancer) = 0.99 = 1 µg/L

The units µg/L are equivalent to parts per billion (ppb).

If the TR had been set at 1E-4, the resulting Adjusted GCCPCBs would have been 10 ppb. If the TR had been set at 1E-6, the Adjusted GCCPCBs would have been 0.1 ppb.

It is possible that an adjusted GCC for PCBs based on the noncarcinogenic effects of PCBs would be more protective in this scenario. EPA Reference Doses (RfDs) for different Aroclors (commercial mixtures of PCBs containing varying percentages of chlorine) were compared to determine the most protective RfD to use. A Reference Dose is an estimate of the daily lifetime exposure to a chemical that is not expected to cause adverse (noncancer) effects. The RfD has safety factors calculated into its value to account for uncertainties when extrapolating from laboratory or epidemiological (human data) research results to anticipated human results. The RfD for Aroclor 1016 is 0.07 µg/kg/day (7.0E-5 mg/kg/day); it is based on reduced birth weight in monkeys ( EPA 1996a). However, the RfD for Aroclor 1254, based on effects seen on the immune system in monkeys, is 0.02 µg/kg/day (2.0E-5 mg/kg/day; EPA 1996b), and it is a more protective value. Therefore, this value will be used to derive an adjusted GCC for the noncarcinogenic effects of PCBs.

The equation used to determine the GCC of a non-carcinogen is below (MDEQ 2001b):

GCC sub noncarcinogen equals THQ times RfD times BW times AT times CF1 divided by SA times SP times EV times EF times ED times CD2

The values for BW, SA, SP, EV, EF, ED, CF1, and CF2 remain the same as discussed above for carcinogens.

THQ is the target hazard quotient. An expected dose is compared to the reference dose, resulting in a hazard quotient, that is, the expected value divided by the reference value. If the quotient is less than or equal to 1, the expected dose is generally considered to be acceptable. The THQ in this exercise is the default, 1.

AT, the averaging time for noncarcinogens, is the number of days over which the exposure is averaged, or ED (the exposure duration) times 365 days per year. When a person is exposed to a noncarcinogen, it is believed that, unlike exposures to a carcinogen, a certain threshold must be reached before adverse health effects occur. Therefore, AT for noncarcinogens represents only the exposure period, not the average human lifespan as for carcinogens. Because it was assumed that children age 9 to 12 would swim in the Canal, AT for this exercise is 3 years (ED) times 365 days/yr or 1,095 days. (This appendix and Appendix F of the Public Comment Draft Health Consultation incorrectly determined ATs for noncarcinogens. The correct ATs are shown in this Final Health Consultation.)

The adjusted GCC for the noncarcinogenic effects of PCBs is calculated as follows:

Adjusted GCC sub PCBs (noncancer) equals 1 times 2.0E minus 5 times 31.5 times 1,095 times 1E plus 3 divided by 11,600 times 1.95 times 1 times 60 times 3 times 1E minus 3

AdjustedGCCPCBs(noncancer) = 0.17 = 0.2 µg/L (ppb)

The previous equations demonstrate that a noncarcinogen-GCC for PCBs (0.2 ppb), where children, ages 9 to 12, are swimming in the canals 60 days per year is more protective than a carcinogen-GCC (1 ppb).

MDCH calculated carcinogen- and noncarcinogen-GCCs for adults to compare the criteria for adults who live along the canals for 30 years and swim in the canals 60 days per year. In the carcinogen-GCC equation, AT, TR, CF1, SF, SP, EV, EF, and CF2 remain the same. BW for adults is 70 kg. The median SA for an adult male is 1.94 m2 (19,400 cm2; EPA 1997a). ED is 30 years, the national upper-bound time (90th percentile) at one residence (EPA 1989). The resulting adjusted GCC for the carcinogenic effects of PCBs, for this scenario, is 0.13 (0.1) ppb. In the noncarcinogen-GCC equation, THQ, RfD, CF1, SP, EV, EF, and CF2 remain the same. BW, SA, and ED are 70 kg, 19,400 cm2, and 30 years, respectively. The resulting adjusted GCC for the noncarcinogenic effects of PCBs for this scenario is 0.23 (0.2) ppb. The preceding calculations demonstrate that the exposure scenario determines which type of health effect (cancer or noncancer) drives the risk for PCB exposure.

Barium, toluene, and total xylenes are not classified as carcinogens. The RfDs for barium, toluene, and total xylenes are 0.07, 0.2, and 2.0 mg/kg/day, respectively ( EPA 1991, 1994, 1999).

The SPs for barium, toluene, and total xylenes are 0.002, 0.086, and 0.13 cm/event, respectively (2002, J. Crum, MDEQ Environmental Response Division, personal communication).

The adjusted GCC for barium is calculated as follows:

Adjusted GCC sub Barium equals 1 times 0.07 times 1,095 times 1E plus 3 divided by 11,600 times 0.002 times 1 times 60 times 3 times 1E minus 3

AdjustedGCCBarium = 18,355 µg/L (ppb)

The adjusted GCC for toluene is calculated as follows:

Adjusted GCC sub Toluene equals 1 times 0.2 times 1,095 times 1E plus 3 divided by 11,600 times 0.086 times 1 times 60 times 3 times 1E minus 3

AdjustedGCCToluene = 1,220 µg/L (ppb)

The adjusted GCC for total xylenes is calculated as follows:

Adjusted GCC sub Total Xylenes equals 1 times 2.0 times 1,095 times 1E plus 3 divided by 11,600 times 0.13 times 1 times 60 times 3 times 1E minus 3

AdjustedGCCTotalXylenes = 8,068 µg/L (ppb)


APPENDIX F: ADJUSTMENT OF MDEQ RESIDENTIAL DIRECT CONTACT CRITERIA TO ADDRESS CONTACT WITH CONTAMINATED SDEIMENTS IN THE LANGE/REVERE CANAL

The purpose of the MDEQ Residential Direct Contact Criteria (DCC) is to protect against adverse health effects due to long-term ingestion of and dermal exposure to contaminated soil. The DCC is protective only of chronic, not acute, effects, and it does not address inhalation of any volatiles. The Residential DCC may be adjusted to address the protection of residents who may come into contact with contaminated sediments, such as by standing in the Lange/Revere Canal. This exercise will demonstrate how the criteria were adjusted to account for a person standing in the Canal. Adjusted criteria for carcinogenic and noncarcinogenic effects are calculated and compared.

PCBs are probable carcinogens (EPA 1997b). The equation used to determine the Residential DCC of a known or probable carcinogen is below (MDEQ 2001c):

Residential DCC sub carcinogen equals TR times AT times CF divided by SF times [(EF sub i times IF times AE sub i) plus (EF sub d times DF times AE sub d)]

TR is the target cancer risk, or the acceptable risk. An "acceptable" risk may range from one in ten thousand to one in one million, meaning that no more than one additional person in ten thousand (1E-4) or one million (1E-6) persons who are exposed to a specific carcinogen will die from cancer compared to a similar population not exposed to the carcinogen. The target risk in this exercise is set at one in one hundred thousand (1E-5).

AT is the averaging time factor, which, for carcinogens, is equivalent to the average human lifespan of 70 years, or 25,550 days. When a chemical is found to be carcinogenic in laboratory animals, the research typically involves a high dose of the chemical given to the animal over a short period of time. Based on the assumption that a high dose of a carcinogen received over a short period of time is equivalent to a corresponding low dose spread over a lifetime, human exposures are calculated by prorating the total cumulative dose over an average person's lifetime.

CF is the conversion factor used so that the appropriate units appear in the product of the equation. This factor is equal to one billion micrograms per kilogram (1E+9 µg/kg).

SF is the oral cancer slope factor, which is an estimate of the increased cancer risk from a lifetime exposure to a chemical. It is a probability estimate that is used only for comparative purposes. It is not a predictive tool. PCBs have been assigned varying slope factors based on level of exposure-specific risk and persistence. The slope factor chosen for this exercise is 2 per milligram per kilogram-day [2 (mg/kg-d)-1]. It reflects high risk and biological persistence (EPA 1997b) and is the most protective value to use.

EFi is the ingestion exposure frequency. It is assumed in this exercise that a person would be exposed to the sediment in the Canal (by standing in it) no more than 12 days per year.

IF is the age-adjusted soil ingestion factor. It assumes that a child through the age of six years eats 200 mg of soil per day, and that an adult will eat 100 mg of soil per day for 24 years. Each ingestion total is divided by the respective default body weight and the resulting quotients are summed. In this exercise, the ATSDR default child body weight of 10 kg was used rather than the EPA default of 15 kg, to provide greater protection. Therefore, IF in this exercise is equal to 154 mg-year/kg-day.

AEi is the ingestion absorption efficiency (a science-based estimate of what percentage of a chemical is absorbed through the gastrointestinal tract) and is chemical-specific. The value for PCBs is 0.5 (50 percent; 2002, J. Crum, MDEQ Environmental Response Division, personal communication).

EFd is the dermal exposure frequency. Similar to EFi above, it is assumed that a person would be exposed to the sediment in the Canal no more than 12 days per year.

DF is the age-adjusted soil dermal factor. It considers the skin surface area (SA), a soil adherence factor (AF), number of events per day, and the exposure duration and divides the product of those factors by the body weight. Respective subfactors are determined for a child and an adult and then summed. In this exercise, it was assumed that a child through the age of six years would be exposed from the hip downward, assuming the Canal were not too deep for the child. (Although it is unlikely that children of this age would be standing in the Canal, this population is considered in this exercise in order to calculate a protective value.) The average SA of the legs of a child of either sex, ages 0 to 6 years, is 1,837 cm2. It was assumed that an adult would be exposed from the knee downward. The average SA of the lower legs of an adult of either sex is 2,005 cm2. The AF describes the amount of soil that adheres to the surface of the skin. Generally, wet soil adheres more than does dry soil. Therefore, rather than use the default values that MDEQ uses in derivation of the DCC, the child-in-wet-soil AF of 2.7 mg/cm2 and the adult worker (e.g. irrigation installer) AF of 0.2 mg/cm2 are used (MDEQ 2001c). The numbers of events per day is 1, and the exposure duration is 6 years for a child and 24 years for an adult. As mentioned above, the child BW is assumed to be 10 kg and the adult BW to be 70 kg. The resulting DF is 3,113 mg-year/kg-day.

AEd is the dermal absorption efficiency (a science-based estimate of what percentage of a chemical is absorbed through the skin) and is chemical-specific. The value for PCBs is 0.14 (14 percent; 2002, J. Crum, MDEQ Environmental Response Division, personal communication).

The adjusted Residential DCC for the carcinogenic effects of PCBs is calculated as follows:

Adjusted Residential DCC sub PCBs (cancer) equals 1E minus 5 times 25,550 times 1E plus 9 divided by 2 [(12 times 154 times 0.5) plus (12 times 3113 times 0.14)]

Adjusted ResidentialDCCPCBs(cancer) = 20,579 µg/kg = 21 mg/kg

The units mg/kg are equivalent to parts per million (ppm).

If the TR had been set at 1E-4, the resulting Adjusted Residential DCCPCBs would have been 210 ppm. If the TR had been set at 1E-6, the resulting Adjusted Residential DCCPCBs would have been 2.1 ppm.

It is possible that an adjusted DCC for PCBs based on the noncarcinogenic effects would be more protective in this scenario. EPA Reference Doses (RfDs) for different Aroclors (commercial mixtures of PCBs containing varying percentages of chlorine) were compared to determine the most protective RfD to use. A reference dose is an estimate of the daily lifetime exposure to a chemical that is not expected to cause adverse (noncancer) effects. The RfD has safety factors calculated into its value to account for uncertainties when extrapolating from laboratory or epidemiological (human data) research results to anticipated human results. The RfD for Aroclor 1016 is 0.07 µg/kg/day (7.0E-5 mg/kg/day) and is based on reduced birth weight in monkeys (EPA 1996a). However, the RfD for Aroclor 1254, based on effects seen on the immune system in monkeys, is 0.02 µg/kg/day (2.0E-5 mg/kg/day; EPA 1996b) and is a more protective value. Therefore, this value will be used to derive an adjusted DCC for the noncarcinogenic effects of PCBs.

The equation used to determine the DCC of a non-carcinogen is below (MDEQ 2001c):

Residential DCC sub noncarcinogen equals THQ times RfD times AT times CF times RSC divided by [(EF sub i times IF times AE sub i) plus (EF sub d times IF times AE sub d)]

The values for CF, EFi, IF, AEi, EFd, and AEd remain the same as discussed above for carcinogens.

THQ is the target hazard quotient. An expected dose is compared to the reference dose, resulting in a hazard quotient, that is, the expected value divided by the reference value. If the quotient is less than or equal to 1, the expected dose is generally considered to be acceptable. The THQ in this exercise is the default, 1.

AT, the averaging time for noncarcinogens, is the number of days over which the exposure is averaged. In this scenario, the national upper-bound (90th percentile) time at one residence of 30 years (EPA 1989) is assumed. Therefore, AT equals 30 years times 365 days per year, or 10,950 days.

RSC is the relative source contribution factor, which accounts for the fact that there are many chemicals to which people are exposed through a variety of media and activities. It is possible that people who live along the Canal also catch and eat fish from the Canal, part of the Lake St. Clair fishery. If these people are not following the advice in the Michigan Family Fish Consumption guide and are being exposed to PCBs via fish consumption, the majority of their total PCB exposure would come from that activity. For this exercise, it is assumed that only 20% of the total PCB exposure would come from standing in the sediment. Therefore, RSC equals 0.2.

The adjusted Residential DCC for the noncarcinogenic effects of PCBs is calculated as follows:

Adjusted Residential DCC sub PCBs (noncancer) equals 1 times 2.0E minus 5 times 10,950 times 1E plus 9 times 0.2 divided by [(12 times 154 times 0.5) plus (12 times 3,113 times 0.14)]

Adjusted ResidentialDCCPCBs(noncancer) = 7,118 µg/kg = 7 mg/kg (ppm)

The previous equations demonstrate that a noncarcinogen-DCC for PCBs (7 ppm), where a person residing along the Canal stands in the Canal sediment 12 times per year for 30 years, is more protective than a carcinogen-DCC (21 ppm). However, if the person were not exposed to other sources of PCBs, such as through the consumption of contaminated fish, then the RSC would be 1 and the noncarcinogen-DCC would be less protective (35 ppm). As discussed in Appendix E, the exposure scenario determines which type of health effect (cancer or noncancer) drives the risk for PCB exposure.

Arsenic is classified as a human carcinogen (EPA 1988). Therefore, the same equation as above is used to adjust the Residential DCC for arsenic. All parameters remain the same except for SF, which is 1.5 (mg/kg-day)-1 (EPA 1988) and AEd, which is 0.03 (3 percent; 2002, J. Crum, MDEQ Environmental Response Division, personal communication). The adjusted Residential DCC for the carcinogenic effects of arsenic is calculated as follows:

Adjusted Residential DCC sub Arsenic (cancer) equals 1E minus 5 times 25,550 times 1E plus 9 divided by 1.5 [(12 times 154 times 0.5) plus (12 times 3113 times 0.03)]

Adjusted ResidentialDCCArsenic(cancer) = 83,306 µg/kg = 83 mg/kg (ppm)

If the TR had been set at 1E-4, the resulting Adjusted Residential DCCArsenic would have been 830 ppm. If the TR had been set at 1E-6, the resulting Adjusted Residential DCCArsenic would have been 8.3 ppm.

Similar to the PCB exercise, MDCH calculated an Adjusted Residential DCC for the non-carcinogenic effects of arsenic. The RfD for arsenic is 0.3 µg/kg/day (3.0E-4 mg/kg/day), based on hyperpigmentation and keratosis of the skin and possible vascular changes seen in exposed humans (EPA 1988). THQ and AT are the same values as in the noncarcinogen-DCC equation for PCBs. CF, EFi, IF, AEi, EFd, DF, and AEd are the same values as in the carcinogen-DCC equation for arsenic. The RSC in this case is 1, because any consumption of locally-caught fish would not contribute to exposure to inorganic arsenic. The adjusted Residential DCC for the non-carcinogenic effects of arsenic is calculated as follows:

Adjusted Residential DCC sub Arsenic (noncancer) equals 1 times 3.0E minus 4 times 10,950 times 1E plus 9 times 1 divided by [(12 times 154 times 0.5) plus (12 times 3,113 times 0.03)]

Adjusted ResidentialDCCArsenic(noncancer) = 1,606,608 µg/kg = 1,607 mg/kg (ppm)

The previous equations demonstrate that a carcinogen-DCC for arsenic (83 ppm), where a person residing along the Canal stands in the Canal sediment 12 times per year for 30 years, is more protective than a noncarcinogen-DCC (1,607 ppm).


APPENDIX G: HEALTH-RELATED QUESTIONS RECEIVED PREVIOUS TO THE PUBLIC COMMENT HEALTH CONSULTATION AND ANSWERS FROM MDCH

From Toxic Free Shores' Nine Demands (#6):

Complete a health study of people in the Emergency Response Site area(s) and make free or low cost tests available for testing people, pets, and property.

At the request of the Macomb County Health Department and the EPA, MDCH is reviewing the data from the Ten Mile Drainage System and the Ten Mile/Lange/Revere canal sampling. The agency is conducting a public health consultation with ATSDR. A health "consultation" is the process of a health assessment and the resulting document. During this process, MDCH forms a health opinion based on the data and community concerns and recommends any necessary public health actions to prevent or stop any harmful exposures. Recommendations could include a health "study," which is an investigation of exposed persons designed to assist in identifying effects on public health. A health study might include taking biological samples or performing epidemiological analysis. However, a health study is not planned at this time.

Additional questions from Toxic Free Shores' on-line news release (May 16, 2002):

What should you do if someone comes into contact with PCBs?

It should be noted first that exposure to (contact with) PCBs does not automatically indicate that you are at risk for developing adverse health effects. The duration of contact, the environmental medium that the PCBs are in (water, soil, air), and the concentration of the PCBs all factor into whether or not health effects would occur.

If you are exposed to PCBs dermally (on the skin), washing right away with soap and water will prevent nearly all of the chemical from being absorbed.

If you are in an area where you know there are high concentrations of PCBs in the air, you should leave that area or, if it is your job to be working with the chemicals, you should be wearing the appropriate respirator.

Often, people will not realize they are consuming PCBs in food. It is prudent to educate oneself on what foods might contain PCBs and how to select and prepare those foods to minimize or eliminate any exposure. For instance, the 2002 Michigan Family Fish Consumption Guide provides guidance on preparing and eating various species of freshwater fish.

How long will these PCBs be around? How long before they break down?

PCBs were used by industries because they resist degradation. Therefore, it can be many years before they break down. That is why EPA is going to be cleaning the sewers and Canal.

How would somebody who may have been exposed to PCBs get medical treatment and/or tested for cancer?

There is a blood test that can be used for measuring exposure to large amounts of PCBs. It should be noted that PCBs are ubiquitous in the environment and that people everywhere probably already have a small amount in their bodies. It is not likely that any exposure persons might have had to PCBs in the Ten Mile Drainage System area would be sufficient to change one's blood level of the chemicals. Concerned persons should consult with their family physician.

Is anyone sick in this area?

There are likely people in this area who are currently sick or not feeling well, just as there would be in any community. There are various tracking systems MDCH operates in the state to monitor for and catch any unusual disease patterns. There have been no reports in this area of illnesses that are likely to be linked to exposure to an environmental contaminant addressed in this document.

From "Just the Facts" May/June 2002 newsletter:

Is my drinking water safe?

Yes. The Canal is not a source of drinking water. Also, as explained in the consultation document, MDEQ has tested the drinking water for the affected area and has not found any contamination.

How can I be exposed to PCBs?

As discussed at the June 5, 2002 public meeting, the most common way people are exposed to PCBs is by eating foods that have PCBs in them. These chemicals tend to reside in the body fat and can be found in meat, dairy products, and fish. Bottom-feeding fish species accumulate some PCBs, then are eaten by larger, predator fish. The PCBs continue to accumulate up the food chain. The 2002 Michigan Family Fish Consumption Guide discusses what species and lengths of fish can be consumed and with what frequency so that people do not accumulate potentially harmful levels of PCBs. The guide also discusses preparation techniques to minimize potential exposure.

While the contamination remains in the Ten Mile Drainage System area, persons might be exposed if they work in the sewers with no protective equipment, if they spend a significant amount of each day near the Lange Street bridge, or if they swim or stand in the Canal. Once the clean-up is complete, these exposure routes will be eliminated

How can PCBs affect my health?

Whether or not a chemical has a harmful effect on a person's health depends upon the dose (the amount that enters the body), the duration of exposure, a person's sensitivity to that chemical, and whether the person is being exposed to other chemicals at the same time. In some cases, a concurrent exposure to a second chemical will counteract the expected effects of the first chemical (antagonism). In other cases, it may increase the magnitude of the effects (synergism).

It cannot be predicted how the health of a person exposed to PCBs will be affected, if at all. The human population is much more diverse and varied than inbred research animals. Research on laboratory animals has shown that PCBs can cause cancer; however, this has not been seen in human subjects. Other animal research suggests that PCBs can affect the immune, endocrine, and reproductive systems. High levels of PCBs, like those seen in industrial or occupational settings, have caused a skin condition called chloracne in workers. Much of the current human research into the effects of PCBs is focused on behavioral and learning differences seen in children of women who ate large amounts of sport fish.

How can I reduce or prevent my exposure to PCBs?

Avoiding the sediments in the Canal, especially at the west end where the storm drain discharges, will prevent exposure to the highest concentrations of PCBs in the Ten Mile Drainage System area. Also, following the Michigan Family Fish Consumption Guide will reduce or prevent exposure to any PCBs in locally-caught fish.

Should canal water be used for lawn irrigation or watering fruits and vegetables?

Ideally, residents should wait until the clean-up is complete before using the Canal water in their yards. Residents who choose to use the Canal to irrigate should position the water intake sufficiently above the sediment becausesince PCBs adhere to soils and sediments more than to water.

Can I swim or wade in the Canal?

It is advised that swimming or wading in the Canal be stopped until the clean-up is complete. Occasional swimming by errant children, especially at the east end of the Canal where concentrations are lower, is not likely to result in any health effects.

Does the Macomb County Health Department consider the Ten Mile Drainage District a health risk?

Based on the information available when the PCB contamination was first discovered, the county health department, along with MDCH and ATSDR, did not consider the contamination to be an imminent (immediate) health risk. An imminent health risk would exist if there were danger of explosion, such as with methane, or a release of a lethal gas, such as cyanide.

From June 5, 2002 Toxic Free Shores Forum:

Has the land been tested for PCB contamination caused by irrigation of the property with water from the Lange Street Canal? If not, when will it be tested?

As of the date of this particular meeting, the residential soils had not been tested. Subsequently, however, 16 residential yards have had their soil analyzed for PCBs and metals. (Discussion in consultation document.)

St. Clair Shores and the EPA said 1 ppm was considered safe, yet on the fact sheet [distributed at this meeting, excerpted from the ATSDR ToxFAQs on PCBs] the FDA said food should contain less than 0.2 to 0.3 ppm.

The 1 ppm level used by EPA is a screening level for PCBs in soil, which is not normally eaten by people but may get consumed if someone's hands are dirty. (That number also addresses possible absorption through the skin following dermal contact.) The default (generic) values of how much soil a person might eat are 200 mg/day for a child and 100 mg/day for an adult. The FDA number is pertaining to actual food, which is intentionally eaten and thus, any PCBs in the food would be delivered directly into the body. A person is going to eat more than 100 or 200 mg/day of food. That is why the FDA's number is less than EPA's.

If you dredge up the sediment containing PCBs, are they then airborne?

If the sediment is treated with a demobilizing, thickening agent so that it does not drip out of the trucks, as is the protocol for removal actions, then there should be no increase in PCB air concentrations and therefore no health threat.

Has there been any recommendation for PCB-exposure treatment that has had any documented benefit?

If a person is exposed dermally to PCBs, multiple washings with soap and water immediately following that exposure have been shown to reduce any absorption.

In the cases of PCBs being ingested, the value of administering activated charcoal to decrease absorption is unknown. In rats, rice bran fiber was shown to decrease absorption, but the value in humans is unknown. Generally, people consuming PCB-containing food do not realize the presence of PCBs in the food until well after consumption, when the PCBs have been absorbed by the body.

Isn't the damage or "potential" damage from PCBs not reversible?

Depending on the effect, any effects PCBs may have on body systems may or may not be reversible. Also, the body may compensate when systems are altered, even before any measurable symptoms might be noticed.

Are you aware of anyone doing a study of the effects of the St. Clair Shores PCB levels? Do you think this will happen?

If this question is referring to a health study, then at the time of this particular meeting, there is no plan for a health study to be conducted. If the health consultation concludes that one is needed, it will be recommended.

The fact sheet states that PCBs exist in transformers, capacitors and other electrical equipment. Does this mean that we are also at risk from the above?

You can only be at risk if you are exposed to the PCBs. If a transformer explodes and you come into contact with the PCBs, then exposure is taking place. As long as the equipment remains intact, then you are not being exposed.

From June 17, 2002 Toxic Free Shores forum (taken from unofficial transcripts):

The Macomb County Health Department says that I'm not in danger, but in the same publication ["Just the Facts" May/June 2002] it says it's an airborne contaminant.

PCBs can be found in the air and have been detected in air samples taken from the area. The language in the publication indicates that the county health department does not find the contamination to be an imminent (immediate) health risk. Also, the language earlier in the publication was discussing how a person could be exposed to PCBs in general.

Obviously our concerns are for the children playing in the general area. Will they be safe during clean-up [regarding air concentrations]?

The EPA will set up barriers to prevent people from entering the work areas during the removal. Air concentrations will be monitored and the generation of dusts prevented.

When the sediments are disturbed, will we be at greater risks, and will we be able to stay in our homes?

As stated before, the EPA will be monitoring air concentrations during the removal of the sediment in the Canal. If levels become elevated, the work will stop until provisions can be made to correct the situation. It is not expected that people will be asked to leave their homes.

We live near the mouth of the Canal. I talked to someone at the Health Department and they told me no PCBs were found in the sediment behind our house. Can we water our lawn from the Canal?

Ideally, residents should wait until clean-up is complete to use canal water for irrigating.

How safe is it to swim in the Canal a few houses from the lake? My son swam in there in the past week with some of his friends. Do I need to have him tested, plus talk to the other parents?

Although the PCB concentrations are lower at the east end of the Canal, it would be prudent to avoid swimming in it until the clean-up is finished. If your son just swam there on occasion, he would probably not have been exposed to enough, if any, PCBs to have caused any health effects. We not only look at the level of exposure (the concentration) but at the duration and frequency of exposure as well to determine if health effects are likely.

Last year he went under the bridge, where the contamination is high.

Again, because the exposure was infrequent, even though the concentration was high, it is not likely that he has been exposed to enough PCBs to cause harm

So the kids fishing down at the end, should they be fishing there? Should we put a sign up saying don't fish?

There is already a fish advisory that exists for Lake St. Clair that discusses species and sizes of fish that should be avoided and how to prepare your catch. We can provide you with advisory signs if you want to post them.

I'm just curious about the effects they have on Autoimmune Disorders, people that already have them, or if they can contribute to people acquiring the disease. I've had horrible complications and various health problems in the past years, autoimmune-related.

The body system most sensitive to the effects of PCBs seems to be the immune system. It's difficult, if not impossible, to predict what the impact of PCB exposure would be on a person's immune system without knowing what kind of exposure occurred, for how long, a history of past exposures to PCBs or other chemicals suspected of causing autoimmune effects. Even with that information, no predictions can be made with any certainty. There are any number of factors, some still unknown, that determine whether or not a person is affected by a chemical.

Could these contaminants have possibly been building up since they were banned in the '70s? Also, we've had constant problems with back-up flooding in our basements when it rains. Could the sediments have been building up over time in our home? It wasn't possible to clean our basement 100% every time that it flooded.

There are not adequate data to determine how long the contaminants have been in the sewers and Canal. Because we do not know how long the PCBs have been there, we cannot predict if any sediments associated with the basement flooding contained PCBs.

I've watered my vegetable garden and lawn for 15 years. Children play on the grass. I want my soil tested and I want clear indicators of safe levels of PCBs. Will you be doing that testing?

As of the date of this particular meeting, EPA was planning on sampling yard soils to determine if any contamination has been transferred from the Canal to residential soils via irrigating. Since that time, sampling has occurred. One of 16 yards had detectable amounts of PCBs in it and that level was below the 1 ppm criterion. There is further discussion about the soil sampling in the consultation document.

Regarding posting, children fishing, fishing off bridge. We tell them. Some listen, some don't. There's no posting. Who is responsible for their safety? Is there any plan for posting?

Because much of the land is private property, the county or state health departments cannot automatically go out and post No Fishing or other signs. The signs are available if people want to post their own property.

When is the community going to be told that the Wahby Park Pond is fed by the lake water coming out of the Lange/Revere Canal? Was the spray from the fountain monitored for safety before they were turned off? Will there be postings to tell people to stay away from the water?

The last time Wahby Pond received water from the Canal, according to the City of St. Clair Shores, was in August of 2001. The EPA tested the water in the pond on April 18, 2002 and the sample results were 52 ppb (for one sample). It is possible that this concentration was not an accurate representation of PCBs in the pond. PCBs tend to adhere to soil and sediments rather than enter the water column. The sample was taken near the inlet from the Canal and may have included suspended sediments containing PCBs.

The fountain spray was not monitored prior to being turned off. Although any PCBs in the water could have been volatized from the spray, any vapors would have dispersed rapidly in the ambient air and likely would not have been at concentrations of concern. Also, because people would not spend a majority of their time at the park, the duration of exposure to any PCBs in the air would have been short and would not be expected to cause adverse health effects.

The area around the pond was not posted with signs warning people of the PCBs found in the pond water. The pond is used by waterfowl, and it is likely that parents would discourage their children from playing in the water, to avoid exposure to the birds' waste. Also, because people would not spend a majority of their time at the park, any exposure to PCBs in the pond water would have been short and would not be expected to cause adverse health effects.

Has any testing been done on the retention basin at the foot of Bon Brae, between Bon Brae and Bon Heur? We have several air samples there. These PCBs have to be going into that retention basin. Can somebody give me an answer? The reason I'm so concerned is that I've lived on Bon Brae for 51 years, and we've had almost 100 cancer deaths between Bon Brae and Bon Heur. And we would like to see action.

The Macomb County Health Department has received information (from the citizen who asked this question) regarding the types of cancer cases, years of diagnoses, and addresses of patients along these two streets and has shared that information with MDCH. Previous to the Ten Mile Drainage System investigation, a request had been submitted to MDCH to interpret cancer statistics for the St. Clair Shores area, specifically, those areas covered by the 48080, 48081, and 48082 ZIP codes. The cancer types being studied are breast, lung, prostate, leukemia, and non-Hodgkins lymphoma, as well as all cancers combined. The epidemiologist reviewing these data expects to complete his review as early as October 2002. (This is addressed at the end of the next appendix.) His report will be shared with the Macomb County Health Department and made available to interested parties.

The Michigan Cancer Registry has collected information regarding diagnoses and deaths since 1985. Information by county is available on-line at the MDCH website, under "Statistics and Reports."

We know that carcinogens like arsenic are in the canal water that floats into Lake St. Clair, along with barium, PCB, lead, and others. What should I do to protect myself from these contaminants?

As long as you are not exposed to unsafe levels of these chemicals, you are protected. Once the Canal is dredged during clean-up, the possibility for exposure will be eliminated or reduced such that any remaining levels would not be expected to be harmful.

When do you plan to test the other canals, storm drains, and Lake St. Clair for contaminants in the water, air, fish, and sediment?

The PWO will address testing the other canals and storm drains.

MDEQ is in charge of the Fish Contaminant Monitoring Program. This program analyzes fish samples from throughout the state for chemicals of concern (e.g., PCBs, mercury, pesticides). Fish directly from the canals in the St. Clair Shores area are not sampled, but rather from various areas of Lake St. Clair itself. The most recent sampling from the lake was done in 2001 with testing done on smallmouth bass, walleye, and carp. Sampling in 2002 should occur, though the date is as yet unknown, with carp and walleye being tested. The data gathered by MDEQ are used by MDCH to establish fish advisories for the state's lakes and rivers. The advisory is available on-line at the MDCH (a Quick Link under "Statistics and Reports") and is also available in print by contacting the county or state health department.

Is it safe to boat up and down the canals?

People are asked not to use the Revere/Lange Canal for boating. Even if the operator were to minimize any wake, sediments still could be disturbed. Residents who moor their boats in the Canal should confer with the City and consider moving their boats until the clean-up is complete.


 

APPENDIX H: PUBLIC COMMENTS RECEIVED ON "TEN MILE/LANGE/REVERE DRAINAGE SYSTEM (a/k/a TEN MILE DRAINAGE SYSTEM) PCB SPILL" HEALTH CONSULTATION AND MDCH RESPONSES

MDCH received the comments and questions verbally at community meetings and in written form via e-mail and US mail. Other comments were taken from the Toxic Free Shores website (http://www.toxicfreeshores.org) or forwarded to MDCH from city officials. Similar comments have been grouped together so they can be answered more efficiently. While some comments or questions do not pertain directly to the Draft Health Consultation, they are included here for completeness.

Why was no attempt made to determine length of exposure before the publication of the draft health consultation? It should be determined if the contamination is new, on-going, historical or a re-release of a historical spill.

MDCH and ATSDR concluded that the expected exposure to PCBs in the Canal would be so infrequent that the duration of exposure would have no bearing on public health implications.Exposure was intermittent rather than continuous and by routes that are not as efficient as consumption of contaminated fish is for internalizing PCBs.

The City of St. Clair Shores contracted with two local researchers to determine an approximate length of time of the PCBs in the Canal, for potential litigation purposes if a responsible party were found. Dr. Linda Schweitzer of Oakland University and Dr. Mark Baskaran of Wayne State University performed radiodating and congener-specific analyses of sediment cores they extracted from the Canal. In their report, they conclude that a dumping event may have occurred in the early 1980s and that PCBs have been present in the Canal since the 1960s. They believe the contamination may be due to improper disposal or leakage of PCBs locally. Drs. Schweitzer's and Baskaran's report is available to the public at the City's website, http://www.stclairshores.net , under the PCB Investigation link.

A scientific conclusion cannot be based on inference and assumption without any factual reference. There are a lot of assumptions in this consultation. What scientific data did you use, and from what resources, to draw your conclusions? There should be real-life data about fishing and fish consumption, water use, swimming, etc. All residents should be quickly canvassed and length of exposure must be determined.

MDCH used data presented in the EPA Child-Specific Exposure Factors Handbook (2000) and Exposure Factors Handbook (1997a) to assess exposure at this site. These documents summarize key data on human behaviors and characteristics that affect children's or adults' exposure to environmental contaminants and recommend values to use for these factors. MDCH recognizes that each population is unique and will not completely match the populations from which the information in the handbooks was derived. For purposes of a health consultation, the data in these handbooks are sufficient to assess exposure. However, in this case, if MDCH had determined that exposure to the contaminants was such that adverse effects could occur, then more site-specific information may have been collected to assess public health risks.

While sanitary sewer workers would likely wear personal protective equipment on the job, the same might not be true of workers exposed to storm sewer water. Furthermore, the consultation does not address the potential inhalation exposure utility workers may face.

According to the Macomb County Public Works Office, repair and maintenance work in sanitary and storm sewers is considered a confined-space entry, which requires the worker to wear personal protective gear. This gear would include a Tyvek suit, rubber boots, gloves, hard hat, gas detection equipment, and air tanks with appropriate breathing masks.

The consultation does not consider that children in many neighborhoods play in storm sewers and catch basins and could be exposed to chemicals in the water or sediments in these structures.

The storm sewers and catch basins referred to in the consultation are subsurface structures and should not be easily accessible to children.

The consultation does not take into account the exposure to canal sediment when one swims and plays in the water. This would seem to be a potentially significant exposure that was not considered when the Direct Contact Criteria were adjusted.

MDCH considers contact with the sediment while standing in it as a greater risk for exposure and potential absorption than swimming or playing in water that had re-suspended sediments in it. A dose from exposure to re-suspended sediment would be much smaller than if a person is standing for an extended length of time in the sediment itself. If a person briefly stands in the sediment before continuing to play or swim, the sediment would likely wash off quickly. Because of the extended time one would stand in the sediment during dock or boat maintenance, it is likely that some sediment would remain adhered to the skin before being washed off by hand or spray hose, increasing the chances for absorption. Therefore, MDCH does not consider the incremental dose caused by exposure to re-suspended sediments while swimming to be significant.

The adjusted criteria do not take into account vulnerable populations, such as infants and pregnant women.

Infants and pregnant women are considered potentially vulnerable populations and were discussed in the ATSDR Child Health Considerations section.

Non-cancer endpoints are not considered. Please incorporate by reference the ATSDR Toxicological Profile for PCBs as well as the Record of Decision regarding the Lower Fox River PCB contamination, Volumes 1 and 2, including White Paper No. 12—Hudson River Record of Decision PCB—Carcinogenicity White Paper, and White Paper No. 13—Hudson River Record of Decision PCB—Non-Cancer Health Effects White Paper.

Discussion of non-cancer endpoints has been added to Appendices E and F. The Reference Doses used took into account the most sensitive endpoint observed. This was not a reproductive or developmental effect, but immune system effects in monkeys, in the case of PCBs, and dermal effects in humans, for arsenic.

The ATSDR Toxicological Profile for PCBs was cited in the draft Health Consultation as well as in this final version. The documents for the Lower Fox River in Wisconsin were studied but not cited. The reader should be aware that the Lower Fox River and Hudson River sites are both Superfund sites, whereas the Ten Mile Drainage System was treated as an emergency response site. While all the sites mentioned are or were affected by PCB contamination, their specific designation determines how they are to be remediated. While comparisons can be made, each site is different, with its own remedial course determined by the overseeing regulatory agency.

Could there be a connection between my family's skin problems (pre-cancerous lesions, abscesses, growths) and dermal exposure to the water in the canal?

We are not able to answer this question. The person's own physician is the best resource to provide an answer because he or she knows the patient's full medical history. The patient should inform the doctor about known or suspected exposure to chemical or biological contaminants, not only in the canal but from other sources.

The EPA said that, during the clean-up, water pumped out of the second cell had a level of 24-25 ppm PCBs. This sample was called "a grab sample off the top." If the PCB concentration in the water during the non-boating season was at this level, one would wonder what the concentrations would have been during boating season.

Water samples were not filtered and likely contained suspended sediments. PCBs tend to stay adhered to sediments rather than enter the water column. Therefore, it is possible that the detected concentration of 24-25 ppm represented the concentration of the sediments in the sample in addition to any PCBs in the water itself. The area in which the second cell was placed had received water pumped out of the first cell, likely disturbing the sediments and re-suspending them. Also, setting the sheet piling to enclose the second cell probably disturbed and re-suspended nearby sediments.

Boats using the canal before the PCBs were removed very likely re-suspended sediments. It is not known what the concentration of an unfiltered water sample would have been during boating season.

Is it safe to swim in the canal outside the EPA clean-up zone before the city has it dredged? What is the risk of being in the canal and having open lesions? What is the risk of standing in the boat wells ("cut-outs") in the canal?

Once the physical structure of the canal is returned to its former state (sidewalls shored up, clean-up equipment removed), there will be no public health hazard present. This is not to say there is no danger inherent in swimming in a canal used by boaters.

A person with open lesions who enters the canal is at risk of more easily absorbing through the wound any chemical (such as boat fuel) or infectious microorganism (such as E. coli from waterfowl droppings) present in the canal.

Standing in the "cut-outs" should not be of concern. The EPA cleaned from wall to wall, and the dredging of the rest of the canal will be from wall to wall.

Should residents continue to water their yards from the canal or walk on the lawn after watering?

Now that the clean-up has finished, residents may water their yards with canal water and walk on the lawn after watering.

When raking weeds and muck out of the canal, should I worry about touching them before bagging them for trash?

Because the storm sewer discharges into the canal, it is probable that trash that enters the sewer will accumulate in the weeds and muck in the canal and be raked out with them. It is possible that the trash would contain sharp objects, such as glass, a more immediate hazard than exposure to any chemicals present. Therefore, it would be prudent to wear gloves when handling the weeds and muck.

Would you drink water with 10 ppm PCBs?

The EPA Maximum Contaminant Level for PCBs in public drinking water supplies is 0.5 ppb (parts per billion). Therefore, public drinking water supplies should be considered safe. It is possible that a person might unwittingly drink canal water while swimming. If a person questions the purity of the water, the person should not drink it.

I really have a problem believing that fish residing in the canals are no more contaminated than those in Lake St. Clair. Fish spawn in the canal, both panfish and perch. The health consultation does not address catching and eating fish from the canal over the years. Was fish consumption a factor in the health consultation? Should residents be consuming fish from the canals? When catching fish, is touching them going to cause health effects?

According to a Michigan Department of Natural Resources (MDNR) fisheries biologist who has worked in the Lake St. Clair area (including connecting canals and marshes) since 1987, fish movement in and out of the canals is routine. Some fish species such as bluegill, pumpkinseed, or largemouth bass may be more "canal" resident than others such as smallmouth bass, yellow perch, or black crappie (which are considered "seasonally" present in the canals), but he would expect all species to move within and between canals in a local area (2003, M. Thomas, MDNR Mount Clemens Fisheries Research Station, personal communication).

Use of the canals for spawning is likely for yellow perch, bluegills, largemouth bass, crappie, and carp, among others. Some species are broadcast spawners and will spawn over any substrate. Others, such as bluegill and bass, prefer a sand or gravel bottom. They will seek out small pockets of sand or gravel along seawalls or bottom debris and spawn in those areas (2003, M. Thomas, MDNR Mount Clemens Fisheries Research Station, personal communication).

The health consultation does address that fish taken from the canal might have elevated concentrations of PCBs or certain metals or pesticides (see Human Exposure Pathways—Water section); however, contamination of the fish can occur outside the canal area due to the historic contamination of the Great Lakes. Discussion has been added to the Toxicological Evaluation—PCBs and the ATSDR Child Health Considerations sections regarding consumption of PCB-contaminated fish, whether or not the fish came from the canals in question.

If the advice in the MDCH Family Fish Consumption Guide regarding what size and species of fish to consume and how to prepare it is followed, then the risk of exposure to PCBs via fish consumption will be reduced or eliminated.

Touching a fish, say to remove a hook, would not put a person at risk of exposure to PCBs. The chemical is within the flesh of the fish and not in the scales. The small amount of any PCB-contaminated water dripping from the fish when it is pulled from the canal would not be sufficient to warrant concern for dermal exposure. The most efficient way for any PCBs to enter your body is to eat a contaminated fish that is not adequately filleted and cooked.

It should not be assumed that the community is aware of the fish consumption advisories or, even if they are aware, that this advice is followed.

While people cannot be forced to read the advisory or follow its advice, health departments use various means to educate the public about health implications of eating Great Lakes fish: the Michigan Family Fish Consumption Guide is available where fishing licenses are purchased; posters discussing the fish advisory and how to obtain more information were made available at the public meetings MDCH attended for this site; and a sign from the Macomb County Health Department was posted at the canals advising people not to swim or fish in the canals.

A number of studies have shown that people who regularly eat Great Lakes fish are more heavily exposed to PCBs and mercury than the general population. The people who live along the canal likely represent a greater than average number of anglers and likely eat a higher proportion of sport fish than the general population. This significant source of PCBs (fish) should be considered when determining the relative risk of additional PCB exposure (canal water and sediment).

It is true that people who regularly eat Great Lakes fish, especially sport fish, are more heavily exposed to PCBs and methylmercury. Eating contaminated fish is the most likely route of exposure to these chemicals for the general population. People living along the canal are known to ice-fish in the canal during winter and may be exposed to PCBs by eating their catch, especially if they do not follow the recommendations in the MDCH Fish Advisory, since the fish are considered part of the Lake St. Clair fishery, covered by the Advisory. However, the exposure to canal water and sediment that is expected to occur should not be sufficient to cause adverse health effects, nor is this incremental exposure expected to contribute significantly to a person's overall potential exposure to PCBs. Discussion has been added to the Toxicological Evaluation–PCBs section regarding consuming PCB-contaminated fish, whether or not the fish came from the canals in question.

Original yard samples taken for analysis were from five locations in each yard and mixed to be tested as a single sample. MDEQ sampled only 16 yards, whereas 111 other yards could have been affected. It is not clear how the 16 yards were chosen for sampling; the samples may not represent the most highly exposed yards along the canal.

When EPA conducted the original sampling, field staff first interviewed the residents along the Canal regarding their use of canal water. Based on the interviews, EPA sampled from yards most likely to be contaminated. Analytical results showed that PCBs had not been transferred from the Canal to the yards. However, results indicated that there were elevated arsenic levels in some yards. MDEQ re-sampled yards with levels greater than 18-20 ppm arsenic, the typical background concentration in eastern Michigan. One yard requires further evaluation. MDEQ should complete its investigation during the summer of 2003.

Please provide a final ruling on the safety of eating vegetables grown in the soil even without watering from the canal. The health consultation said there were unsafe levels of arsenic in the soil, yet MDCH said it was safe. Which is it?

The health consultation stated that levels of arsenic in some of the yard samples were above state criteria, not that they were unsafe. In regard to residential gardens, there was a paragraph in the Toxicological Evaluation discussion on arsenic: "Garden plants might accumulate arsenic by root uptake from the soil, the degree of uptake being affected by the speciation of the arsenic compound. However, even when grown on highly polluted soil or soil naturally high in arsenic, plants have been shown to accumulate comparatively low levels of the metal (ATSDR 2000a). Therefore, any arsenic that might accumulate in produce grown in yards shown to have elevated levels of arsenic is not expected to be at levels that would cause adverse health effects." Therefore, no health threat is posed by the arsenic in the soil along the Lange and Revere canals when people are eating produce grown in that soil.

The resident living where the 81 ppm of arsenic was detected in the soil claims that they do not have treated-wood mulch on their garden. Please verify.

MDCH called the resident and discussed the area where the soil had 81 ppm arsenic. Apparently, the previous resident had enclosed the raised-bed garden with treated lumber. It is likely that the treated lumber leached arsenic into the soil. This point has been corrected in the consultation.

While only one air sample out of eight taken before the clean-up began exceeded the ATSDR CREG of 10 nanograms per cubic meter (ng/m3, or 0.01 micrograms per cubic meter [µg/m3]), this represents 12.5% of the air samples taken. The ATSDR Toxicological Profile for PCBs states that inhalation exposure is considered to be a major route of exposure to PCBs, noting a 1998 ferret study by Apfelbach et al. Air exposure needs to be considered in the overall exposure assessment.

While the percentage of air samples with a CREG exceedance is mathematically correct, it does not have statistical power and therefore cannot be used to suggest that the number of exceedances is substantial.

The language in the ATSDR Toxicological Profile for PCBs, section 3.4.1.1, states, "Inhalation exposure is considered to be a major route of occupational exposures to PCBs" (ATSDR 2000b, emphasis added by MDCH). Occupational concentrations of chemicals, such as in capacitor work, are typically much greater than those found at sites of environmental contamination.

In the Apfelbach et al. study, ferrets were exposed to 260 ng/m3 (0.26 µg/m3) PCBs in air over five years. The main site of PCB distribution was the olfactory bulbs, but concentrations of the chemicals were also found in the liver, fat tissue, and brain. This was not a nose-only exposure, so dermal exposure may have contributed to the findings. While the levels in the study were considered low, 260 is 26 times greater than the ATSDR CREG (10 ng/m3) and more than 16 times greater than the reported exceedance (16 ng/m3). ATSDR states in the Toxicological Profile that the study results are not conclusive and more research is needed in this area.

MDCH did consider in the health consultation whether air exposure contributed significantly to overall exposure and concluded that the incremental contribution was insignificant.

Do PCBs in the air cause health effects, such as headaches, nausea, etc.?

The ATSDR Toxicological Profile for PCBs does not report that any acute effects were seen in humans following inhalation exposure. The results of chronic exposure in humans are inconclusive. Most human data are derived from occupational studies, in which PCB concentrations typically would be much higher than at sites of environmental contamination.

Indoor air samples should be taken to determine if drains inside a home are a significant source of PCBs to the air and if repeated sewer backups result in elevated air levels of PCBs in basements.

MDCH does not recommend testing the indoor air for PCBs. To protect the occupants of a house from dangerous methane levels from a sewer, the drain should have a U-shaped trap that prevents gas from entering the structure. Therefore, chronic exposure to PCBs in indoor air is not expected to occur.

Sewer backups could introduce PCBs into the indoor air if contaminated water or sediment enters the house. However, during the cleaning up, a homeowner would likely increase the ventilation in the house to help remove any odors. Therefore, any exposure to PCBs in indoor air following a sewer back-up would be of a short duration and would not be expected to cause adverse health effects.

More testing (of Lake St. Clair, other canals, drains, outflows, and sewers) is needed to determine the full extent of contamination. This characterization should have occurred before clean-up efforts began to ensure that the clean-up plan was adequate. The testing is still warranted, to ensure all contaminated areas have been found and addressed and to verify that PCBs have not been re-released or moved as a result of clean-up efforts. Accidental releases may have occurred during the September 7, 2002 incident when an oily black liquid was washed from the storm sewer into the canal and during the December 30, 2002 incident when a barge entered the canal and the excavator on it used its scoop to push on the bottom of the canal to move the barge.

The immediate concern for this site was the contamination in the storm sewer and the canal. As testing of the canal water and sediment proceeded eastward out of each arm of the canal, less and less contamination was found, indicating that the contamination was localized. While it may be possible that other sites, in St. Clair Shores or elsewhere, have as yet unknown levels of hazardous chemicals, EPA determined that contamination at this site was contained to the sewers and the canal. Therefore, EPA addressed that contamination, per its mandate, as a time-critical removal action to prevent further contamination. During all phases of the removal, follow-up testing was done to ensure that EPA had met its clean-up goals.

It is unfortunate that the oil plug washed out of the sewer on September 7 before it could be contained, and that the barge and excavator disturbed the sediment on December 30. Ideally, every contingency can be planned for, but realistically, incidents such as these can happen. It is likely that any contamination caused by these incidents was minimal compared to the contamination that ended up being removed.

Wildlife data must be considered in the health consultation, as these data often can provide important information about extent of the contamination, historical trends, and potential human health effects. Wildlife data can reveal subtle functional losses, immune system problems, etc., that are relevant to the human population and that come from organisms living in the same environment and eating the same fish as humans in the watershed.

Wildlife data can provide useful information regarding potential human health effects from contamination but, in this case, they would have limited, if any, use. The geography and human use of this site does not lend itself to being good habitat for top predators, such as mink, otter, or eagles, which are among the most sensitive indicator species for environmental quality. While portions of the Lake St. Clair shoreline may provide feeding habitat for great blue herons, another predator species, the canals themselves would not be a preferred hunting area for this wading bird due to the depth of the canals. Although photos have shown ducks, geese, and turtles using the canals, these species do not eat much fish and are therefore less favorable for comparing to humans.

If there is no apparent public health hazard, why have warnings about PCB health risks?

Ideally, there will be no exposure to these compounds. However, exposure has occurred, though it likely was not sufficient to cause adverse health effects. People should be aware of chemicals to which they are being exposed and what the health risks for long-term exposure are.

What is the length of time between exposure and disease?

It is impossible to determine the latency, or time, between exposure to a chemical and development of any disease with which it might be associated. A multitude of factors, chemical-specific and person-specific, ultimately determine the action of a chemical. Some of these factors act cooperatively, whereas others counteract each other. The best defense against disease is knowledge and working with your healthcare provider in monitoring your overall health.

There is a vocabulary concern in the health consultation, in the Public Health Action Plan section. The verbage is "exposure not confirmed"; however, exposure has occurred. Please clarify the language.

The language has been clarified.

Only "total" PCBs were considered in the consultation. A more precise evaluation would include a congener-specific analysis of the PCBs present and the relative toxicity of those congeners.

It is true that a congener-specific analysis would have been provided a more precise characterization of the contamination. However, the point is moot because expected exposure likely is not sufficient to cause adverse effects.

Also, it is not known how the individual components of complex mixtures of chemicals, such as PCBs in the environment, may interact. The PCB results obtained in this investigation were matched to the most likely Aroclor (a commercial mixture of PCBs) profile, based on analytical results and professional judgment of laboratory scientists. Aroclors have been extensively studied, whereas all 209 individual PCB congeners, alone or in any combination, have not. Therefore, EPA used appropriate scientific methods to characterize the contamination.

Polybrominated biphenyls (PBBs) were not considered in the consultation. Some PBBs are dioxin-like in their activity and must be considered as additive to other PCB exposures. In order to be complete and accurate, all related compounds must be considered when assessing potential health impacts.

It is true that considering all dioxin-like compounds in the assessment would have yielded more information. However, as explained previously, the expected exposure to the chemicals is not likely to cause adverse effects.

Can the boat fuel floating on top of the water cause health effects? How does this risk compare to the risk of the remaining PCBs?

People using the canal would be exposed more readily to boat fuel floating on the surface of the water than to PCBs in the sediment. Because the fuel is more volatile than PCBs and would be exposed directly to air, people could be exposed via inhalation. Swimmers who might swallow some canal water would ingest a minute amount of fuel with the water. It is possible that fuel-contaminated water could irritate the eyes if someone were splashed in the face. Yet, similar to PCBs, because the expected exposure would be minimal, the health risk would also be minimal.

The following discussion is follow-up to a concern raised at the June 17, 2002 Toxic Free Shores forum regarding the perceived cancer rate in St. Clair Shores:

Previous to the Ten Mile Drainage System investigation, a request had been submitted to MDCH to interpret cancer statistics for the St. Clair Shores area, specifically, those areas covered by the 48080, 48081, and 48082 ZIP codes. The cancer types of concern were breast, lung, prostate, leukemia, and non-Hodgkins lymphoma, as well as all cancers combined. The evaluation revealed that only lung cancer showed a higher-than-expected incidence rate. Lung cancer has not been associated with exposure to PCBs. According to the Macomb County Health Department, the county does have a greater than average number of smokers, and smoking is a risk factor for lung cancer.


CERTIFICATION

This Ten-Mile/Lange/Revere Drainage System –Response to Public Comments 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 existing 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.

Roberta Erlwein
Chief, State Programs Section, SSAB, DHAC, ATSDR


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