PUBLIC HEALTH ASSESSMENT
AMERICAN CROSSARM AND CONDUIT COMPANY
CHEHALIS, LEWIS COUNTY, WASHINGTON
ENVIRONMENTAL CONTAMINATION AND OTHER HAZARDS
The tables in this section list the contaminants of concern. We evaluate these contaminants in the subsequent sections of the Public Health Assessment and determine whether exposure to them has public health significance. ATSDR selects and discusses these contaminants based upon the following factors:
In the data tables that follow under the On-site Contamination subsection and the Off-site Contamination subsection, the listed contaminant does not mean that it will cause adverse health effects from exposures. Instead, the list indicates which contaminants will be evaluated further in the Public Health Assessment. When selected as a contaminant of concern in one medium, that contaminant will be reported in all media.
Contaminant concentrations detected on- and off-site are compared to values that are believed to be without adverse health effects upon exposure. Those values are developed by health and regulatory agencies to provide estimates of levels below which health effects would not be observed. Those values, in many cases, have been derived from animal studies. Health effects are related not only to the exposure dose, but to the route of entry into the body and the amount of chemical absorbed by the body. For those reasons, comparison values used in public health assessments are contaminant concentrations in specific media and for specific exposure routes. Several comparison values may be available for a specific contaminant. ATSDR generally selects conservative exposure assumptions in order to protect the most sensitive segment of the population. (The potential for adverse health effects from exposure to contaminants will be discussed in the Toxicological Evaluation section of this document.) Environmental contamination from ACC resulted primarily through five methods during the wood treatment process:
In September 1992, EPA completed a Remedial Investigation (RI) and Feasibility Study (FS) for ACC. Environmental samples were collected during 1990 and 1991. The RI included surface water and sediment samples from Dillenbaugh Creek, the Chehalis River, and the city of Chehalis's storm water discharge lagoon. Soil samples were taken throughout the site and monitoring wells were installed to characterize groundwater and assess the migration of contaminants. The ACC RI involved the collection of 257 biased and systematic, discrete and composite surface and subsurface soil samples, 18 discrete surface water samples, and 50 groundwater samples at the facility and in the AOC. The RI concluded that there was a potential threat to human health, but only a low-to-moderate potential for impacts on the environment (5).
Now the bulk of the contamination is on ACC's facility. In 1986, about 10,000 gallons of PCP in diesel solution were spread by flood waters in the Chehalis Avenue area (5). Today, surface soil in the Chehalis Avenue area is contaminated, but to a lesser degree than soil on ACC (Figures 6,7,8 & 9). Groundwater beneath ACC is contaminated with PCP and PAHs. No chlorinated dioxins or furans were detected in groundwater (1). A layer of oil floating on the groundwater is present beneath the treatment works in one well. No plume leading off-site has been found. Surface water in Dillenbaugh Creek and the stormwater discharge lagoon are contaminated by surface runoff from the area and a Chehalis surface water discharge pipe that runs under ACC (Figure 10)(5).
To identify possible facilities that could contribute to contamination in the vicinity of ACC, WDOH searched the Toxic Chemical Release Inventory (TRI) Database by zip code for all available years (1987, 1988, 1989, 1990, and 1991). TRI was developed by EPA from information regarding chemical releases into the air, water, and soil, as provided according to law by certain industries. TRI contained information for thirty three (33) releases in ACC's zip code. None of the hazardous substances released were of concern at ACC. Coal Creek is a "Superfund" NPL site about one mile northeast of Chehalis. At the Coal Creek site electric transformers were dismantled and polychlorinated biphenyls (PCBs) were released to the environment (1).
The contaminants of concern at ACC are pentachlorophenol (PCP), polycyclic aromatic hydrocarbons (PAHs), and polychlorinated dioxins/furans (dioxin).
Soil
Levels of on-site surface soil contamination were as high as 130 mg/kg (ppm) for PCP, CPAHs were
as high as 258 ppm, and dioxin was 0.143 ppm (Table 1). Surface soil samples were taken to a
depth of four inches below ground surface. On-site subsurface soil samples ranged from ND-250
ppm PCP and ND-54.59 ppm CPAHs (Table 2) (Figures 11, 12) (5). The subsurface soil samples
were taken from a depth of one to sixty-nine feet below ground surface.
TABLE 1
ON-SITE SURFACE SOIL
| Contaminant | Range of Concentration |
Comparison Value | |
| Source | |||
| Pentachlorophenol (PCP) | ND-130 | 6 (B2) | CREG |
| Carcinogenic Polycyclic Aromatic Hydrocarbons (CPAHs) * |
ND-258 | 0.1 | CREG |
| Dioxin # | 0.000179-0.143 | .00000005 (B2) | EMEG |
(Adapted from reference 1) ND = Non Detect
#Dioxin concentrations are in terms of 2,3,7,8-TCDD and were converted using Toxic Equivalency
Factors (TEF) as specified by the North Atlantic Treaty Organization Committee on Challenges to
Modern Society B2 = EPA Cancer Class/probable human carcinogen (inadequate human, sufficient
animal studies)
* value for benzo(a)pyrene (PAH).
TABLE 2
ON-SITE SUBSURFACE SOIL
| Contaminant | Range of Concentration |
Comparison Value | |
| Source | |||
| Pentachlorophenol (PCP) | ND-250 | 6 (B2) | CREG |
| Carcinogenic Polycyclic Aromatic Hydrocarbons (CPAHs) * |
ND-54.59 | 0.1 | CREG |
| Dioxin # | ND | .00000005 (B2) | EMEG |
(Adapted from reference 1) ND = Non Detect #Dioxin concentrations are in terms of 2,3,7,8-TCDD and were converted using Toxic Equivalency Factors (TEF) as specified by the North
Atlantic Treaty Organization Committee on Challenges to Modern Society B2 = EPA Cancer
Class/probable human carcinogen (inadequate human, sufficient animal studies)
*value for benzo(a)pyrene (PAH).
Groundwater
Groundwater contamination is present at three discrete localized areas located beneath the treatment area within the facility boundary (Figure 13). PCP is present near the treatment works in a dissolved phase and as a floating phase mixed with diesel. The floating phase has PCP concentrations as high as 12,000 ppm. A dissolved PCP concentration of 91 mg/L (ppm) was detected in groundwater below the floating product. Samples from monitoring wells west of the kilns were found to be contaminated with PAHs (5).
Soil
The highest contaminant levels in soil off-site were PCP 13 ppm, PAHs 32 ppm, and dioxin 0.00136
ppm (Table 3). Surface soil samples in the Chehalis Avenue area were largely collected from
residential lawns and exposed soils in flower beds or gardens to a depth of four inches.
Concentrations of the primary contaminants in the area east of Pacific Avenue were orders of
magnitude less than in the area west of Pacific Avenue, and decreased with distance north to Lewis
Street and east of Pacific Avenue (1).
TABLE 3
OFF-SITE SURFACE SOIL
CHEHALIS AVENUE AREA
| Contaminant | Range of Concentration |
Comparison Value | |
| PPM | Source | ||
| Pentachlorophenol (PCP) | ND-13 | 6 (B2) | CREG |
| Carcinogenic Polycyclic Aromatic Hydrocarbons (CPAHs) * |
ND-32.9 | 0.1 | CREG |
| Dioxin # | ND-0.00136 | 0.00000005 (B2) | EMEG |
(Adapted from reference 1) ND = Non Detect #Dioxin concentrations are in terms of 2,3,7,8-TCDD and were converted using Toxic Equivalency Factors (TEF) as specified by the North
Atlantic Treaty Organization Committee on Challenges to Modern Society B2 = EPA Cancer
Class/probable human carcinogen (inadequate human, sufficient animal studies)
*value for benzo(a)pyrene(PAH)
Surface water
Surface water collected from the Chehalis River, Dillenbaugh Creek, and the stormwater discharge lagoon contained ND-0.0008 ppm PAHs, ND-0.019 ppm PCP, and a maximum concentration of 0.0000008 ppm of dioxin. Surface water samples were collected from the Chehalis River downstream of its confluence with the Newaukum River. Dioxin was found in the surface water at concentrations ranging from 0.000000008 to 0.000000023 ppm (5).
Sediments
Sediment samples were taken from Dillenbaugh Creek, the stormwater discharge lagoon, the
wetlands, and the Chehalis River. Dioxin and PAHs were found in a majority of the samples with
maximum concentrations of 0.000593 ppm and 36.65 ppm, respectively. PCP was detected in less
than half the sediment samples and had a maximum concentration of 0.19 ppm (5). Sediments from
the wetlands were found to be contaminated with PAHs, dioxin, and PCP. PAHs and dioxin were
detected in nearly all samples and had maximum concentrations of 11.7 ppm and 0.000155 ppm,
respectively. The maximum concentration of PCP detected was 0.28 ppm.
TABLE 4
CONTAMINANTS IN THE
STORMWATER DISCHARGE LAGOON
| Media | Contaminant | Range of Contamination (PPM) |
Comparison Value | |
| PPM | Source | |||
| Surface Water | CPAH* | ND | 5 | CREG |
| PCP | 0.00014-0.068 | 300 | CREG | |
| Dioxin | ND-0.00000061 | 0.01 | EMEG | |
| Surface Sediment | CPAH | 0.17-17.3 | 0.1 | CREG |
| PCP | ND-0.16 | 6 | CREG | |
| Dioxin | 0.000173-0.0159 | 0.00000005 | EMEG | |
| Subsurface Sediment |
CPAH | none available | 0.1 | CREG |
| PCP | none available | 6 | CREG | |
| Dioxin | ND-0.087 | 0.00000005 | EMEG | |
| Surface Soil near Lagoon |
CPAH | 0.088-1.1 | 0.1 | CREG |
| PCP | ND-0.79 | 6 | CREG | |
| Dioxin | Not Analyzed | 0.00000005 | EMEG | |
(Adapted from Ref. 1) ND = Non Detect *CPAH = Carcinogenic Polycyclic Aromatic Hydrocarbons
C. Quality Assurance and Quality Control
In preparing this Public Health Assessment, The Washington State Department of Health relies on the information provided in the referenced documents and assumes that adequate quality assurance and quality control measures were followed with regard to appropriateness of testing procedures, chain-of-custody, laboratory procedures, and data reporting. The validity of the analyses and the conclusions drawn for this Public Health Assessment is determined by the availability and reliability of the referenced information.
On January 19, 1993, the Department of Health, with the Department of Ecology, made a site visit. On January 26, 1994, a second site visit was made by the Department of Health with the Environmental Health Director for Lewis County. Large dilapidated buildings, demolition debris, tarp covered piles, barrels, and open space characterize the site.
The fence line on the south side of ACC is adjacent to a play field. The wood slat fence is seven-feet high. The fence is intact, but could be easily pried opened. Several slats have been recently renailed. ACC is open to entry on the west side. People who enter the site are susceptible to injury among the dilapidated and partially burned structures. Because of marshy land, ACC's buildings of massive timbers were constructed on pilings. Repeated structural fires on-site have weakened some of the wood supports, making parts of the buildings extremely hazardous. ACC remains a physical hazard, as reported in the 1990 PHA (3).
This section will focus on the migration of contaminants and how human exposure may occur. To determine if human populations are exposed to contaminants migrating from the site, ATSDR and WDOH evaluate the environmental and human activities that lead to human exposure. This pathway analysis consists of five elements: A source of contamination, transport through an environmental medium, a point of exposure, a route of human exposure, and an exposed population.
ATSDR categorizes an exposure pathway as a completed or potential exposure pathway if the exposure pathway cannot be eliminated. Completed pathways have all five elements and indicate that exposure to a contaminant has occurred in the past, could be occurring now, or could occur in the future. Potential pathways, however, have at least one of the five elements missing. Potential pathways indicate the exposure to a contaminant could have occurred in the past, could be occurring now, or could occur in the future. An exposure pathway can be eliminated if at least one of the five elements is missing and will never be present. Table 5 identifies the completed and potential exposure pathways.
A. Completed Exposure Pathways
Five pathways of human exposure to site contamination have to some degree occurred in the past and may occur now and in the future. The remediation proposed in the Record of Decision will have varying degrees of impact on these pathways in the future.
Flood Waters
The primary transport mechanisms of the contaminants from ACC were on suspended soil in flood water runoff. The 1986 flood probably carried the most contamination off-site because of the presence, and subsequent loss of ACC's wood treatment products. The ACC site was flooded five more times after 1986. When this regional flooding occurred people throughout the affected area were directly exposed to contaminated water at their residences, in town, and on roads. The level of contaminants ingested by people during the flood periods is unknown. The duration of exposure was a matter of weeks. However, when the flood waters receded contaminants were left behind on soil. A dairy products packaging plant is immediately north of the facility. The lower floor of the plant was inundated during the 1986 flood. No data was found on food contamination.
Until the site is remediated future floods could add to the off-site contamination. The amount of future contamination should be less than past floods because the hazardous products have been lost, removed, or contained on site. However, heavy on-site soil contamination has the potential in future floods to increase the level of off-site exposure. However, site flooding is not a scouring event, but rather consists of a back water situation. Also, proposed on-site remediation, when completed, will further restrict off-site migration.
Residential Soil
The people off-site now at the greatest risk of adverse health effects from exposure to site related contaminants live in the area flooded in the past near ACC. These people may incidentally ingest dioxin and PAHs in soil due to hand-to-mouth contact. The proposed remediation intends to remove off-site contaminated soil. This should eliminate future off-site exposure.
Residential Dust
During 1991, EPA spread gravel over parts of the site to keep contaminated dust from becoming
airborne. In the past, the most significant movement of dust off-site probably occurred when the
plant was in operation or removal operations were in progress. Because the site is usually wet,
current dust movement off-site is not significant. However, when remedial actions begin to remove
buildings, soil dust will again contribute to the movement of contaminants. The intended vegetative
cover of the site should reduce this pathway in the future. Even though residential soils are not
highly contaminated the removal of these soils during remediation will increase human exposure
due to the proximity of people.
TABLE 5
Completed and Potential Exposure Pathways
|
Exposure Pathway Elements |
Time | |||||
| Pathway Name | Source | Media | Point of Exposure | Route of Exposure | Exposed Population |
|
| Flood Waters | ACC | surface water | Flooded area around site |
Ingestion Dermal Contact |
residents in flooded area |
past future |
| Residential Soil | ACC | flood water residue |
Flooded area around site |
Ingestion Dermal Contact |
residents in flooded area |
past present future |
| Residential Dust | ACC | dust on wind | Area around site | Ingestion Inhalation Dermal Contact |
residents in area |
past present future |
| Stormwater Discharge Lagoon |
ACC | Storm Drain through Site and flood waters |
Stormwater Lagoon |
Ingestion Dermal Contact |
recreation users |
past present future |
| On Site | ACC | soil, surface and groundwater |
ACC Site | Ingestion Dermal Contact Inhalation |
trespasser and site workers |
past present future |
| Drinking Water | ACC | groundwater | tap water | Ingestion | residents | future |
Stormwater Discharge Lagoon
Runoff in the vicinity of ACC travels from Chehalis Avenue across ACC to the wetland or a stormwater discharge lagoon and eventually to Dillenbaugh Creek and the Chehalis River. A surface water discharge pipe runs through ACC from Chehalis to the discharge lagoon. Surface run-off from other industry in the area flows to the lagoon. A large area of demolition debris is north of and adjacent to the lagoon. Contaminants from all of these sources could end up in the lagoon and subsequently drain from the lagoon to the creek or river. Recreational use of the area around the lagoon does occur, but infrequently.
On Site
Ground and surface water and soil remain contaminated on site. The site is partially fenced, but not secured to casual entry. Trespassers and on-site remediation workers will be exposed to contaminants by ingestion and dermal contact. They will also transport contaminants which adhere to their clothing to off-site areas.
B. Potential Exposure Pathways
Drinking Water
Although groundwater beneath the facility is currently not used for human consumption, the presence of contaminants in the soil and groundwater is a potential threat to human health. PCP and PAHs are the primary contaminants identified in groundwater. In groundwater, these contaminants are typically transported as either dissolved constituents, light nonaqueous phase liquids (LNAPL), or as dense nonaqueous phase liquids (DNAPL). PCP was identified in each of these forms on-site, but no contaminants were found in groundwater leaving the site. The proposed remediation for groundwater is to remove floating product on-site. This will not remove contaminants which are dissolved or a DNAPL. Chehalis now obtains drinking water from distant surface sources. If, in the future, the city used groundwater, the ACC contaminants could affect public health.
The Public Health Implications section discusses the potential health effects resulting from exposure to contaminants of concern associated with the completed exposure pathway. Health implications from past, present, and future exposures to contaminants of concern in on-site surface soils, off-site surface soils, and lagoon water are evaluated.
To assess health effects that could result from exposure to site contaminants, daily exposure doses which an individual may receive are estimated. The estimated daily exposure dose is compared to a health-based guideline which defines a level of exposure at which adverse health effects are unlikely to occur. ATSDR has developed Minimal Risk Levels (MRLs), health-based guidelines used to evaluate noncarcinogenic adverse health effects for routes of exposure such as ingestion and inhalation, and for exposure durations including acute (less than 14 days), intermediate (15 days to 364 days), and chronic (greater than 365 days). When MRLs are not available, USEPA health-based guidelines are used. USEPA has developed reference doses (RfDs) and reference concentrations (RfCs) for ingestion and inhalation exposure, respectively.
Where estimated daily exposure doses exceed MRLs or RfDs, we further compare with values called No Observed Adverse Effect Level (NOAEL) and Lowest Observed Adverse Effect Level (LOAEL). Data from human studies are used preferentially, but animal studies can be used to indicate possible human health effects. It should be noted that there are uncertainties when using these estimated doses and NOAELs, and in some cases the exposure may be above or below by a small margin. That small difference may or may not be protective for sensitive individuals or populations.
The assumptions used in calculating the estimated daily exposure dose from exposure to surface soil contaminants include an adult body weight of 70 kilograms (kg) and soil ingestion rate of 50 milligrams (mg) per day, and a child body weight of 16 kg and soil ingestion rate of 100 mg per day. The exposure frequency of a child trespassing onto the site is assumed to be one per week for a period of ten years. Exposure for an adult worker was assumed to be five days per week for 20 years. Ingestion rate for incidental exposure to the surface water at the lagoon was assumed to be 0.004 Liters per day. Exposure frequency was one day per week for ten years. Residential exposure frequency was estimated to be seven days per week.
EPA has reviewed available data from human and animal studies to determine the carcinogenic potential of specific chemicals. For many carcinogens, EPA has derived cancer slope factors or unit risks for oral and inhalation exposure routes. In evaluating carcinogenic health effects, cancer slope factors or unit risks are used with the estimated daily exposure dose to predict the increased risk of developing cancer over a lifetime of exposure (70 years). Normally, as high as 300,000 people out of 1,000,000 develop cancer over their lifetime (7); in this section cancer risk is related as anticipated increase above this rate. Rates of cancer risk is qualitatively expressed in Table 6.
Contaminants of concern were found to be pentachlorophenol (PCP), polycyclic aromatic hydrocarbons (PAHs), and polychorinated dioxins/furans (see Tables 1, 2, and 3).
The authors estimated "worst case scenarios" for off-site residential, commercial, and industrial soils, stormwater lagoon soils and water, and on-site soils for children trespassers and plant workers.
| no increased risk | |
| no apparent increased risk | |
| low increased risk | |
| moderate increased risk | |
| high increased risk | |
| very high increased risk |
Pentachlorophenol (PCP)
PCP is a synthetic organochlorine compound that was used as a wood preservative at ACC. PCP is typically used as a five percent solution in diesel carrier oil. It has moderate solubility in water, but is highly soluble in organic solvents. PCP has a low vapor pressure and therefore does not readily volatilize from soil or water. At the ACC facility, it is expected that most PCP would be associated with the diesel carrier oil or would be bound to the organic component of soil particles (1).
None of the scenarios for PCP revealed estimated exposure doses above MRLs or RfDs. The off-site residential exposure estimate for a child by ingestion was ten times below the MRL, which may or may not be protective for especially sensitive individuals. The scenarios disclosed "no increased risk" for cancer from PCP.
Polycyclic Aromatic Hydrocarbons (PAHs)
PAHs are an ubiquitous class of chemicals that are produced during the combustion of fossil fuels and are present in a variety of environmental products such as soot, coal, tar, tobacco smoke, petroleum, and cutting oils. As a class, PAHs consist of three or more benzene rings fused in linear, angular, or cluster arrangements. PAHs present at ACC facility are most likely from diesel carrier oil containing pentachlorophenol (1).
Currently, no information is available from human studies to determine health effects resulting from exposure to specific levels of the individual PAHs, although inhalation and skin exposure to mixtures containing PAHs has been associated with cancer in humans.
Animal studies involving exposures to individual PAHs have revealed adverse health effects including reproductive problems, birth defects, immune system defects, and cancer. With the exception of cancer, these effects have generally not been seen in humans. Based on animal studies, the EPA has classified several individual PAHs as probable human carcinogens. These PAHs include: Benzo(a)pyrene, Benzo(a)anthracene, Chrysene, Benzo(b)fluoranthene, Indeno(1,2,3-cd)pyrene, Dibenzo(a,h)anthracene, and Benzo(k)fluranthene. All of these PAHs have been found at the ACC site.
There is no chronic MRL or Rfd available for total PAH compounds. All of the carcinogenic PAHs were totaled for a maximum concentration level in the calculation of an exposure dose. The Cancer Slope Factor for benzo(a)pyrene was used to evaluate total carcinogenic PAHs. Benzo(a)pyrene is likely to be the most potent carcinogen of the PAHs at the site. None of the scenarios revealed estimated exposure doses above the MRL for benzo(a)pyrene. A "low increased risk" of cancer was noted for 20 year workers at the facility and "no apparent increased risk" for off-site residential soil. The other scenarios exhibited "no increased risk" for cancer from carcinogenic polycyclic aromatic hydrocarbons.
Dioxin
The chlorinated dibenzo-p-dioxins and dibenzo-furans are a class of compounds that are loosely referred to as dioxins/furans. There are 75 dioxin/furan compounds. Of these, 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD) is the most toxic. Dioxins and furans are present as trace impurities in some synthetic chlorinated chemicals. 2,3,7,8-TCDD does not occur naturally, nor is it intentionally manufactured by any industry, except as a reference standard. It can be inadvertently produced in very small amounts as an impurity during the manufacture of certain herbicides and germicides and has been detected in products of incineration of municipal and industrial wastes. The most likely source of dioxin at ACC is the pentachlorophenol used in the wood preservation process (1). All references to dioxin concentrations in this report are in terms of 2,3,7,8-TCDD and were converted using Toxic Equivalency Factors (TEF) as specified by the North Atlantic Treaty Organization Committee on Challenges to Modern Society.
Effects of 2,3,7,8-TCDD exposure, which have been demonstrated only in animals to this point, include immune system toxicity, reproductive effects, and malformation of offspring. Based on the strongly positive evidence in animal studies, the EPA has classified 2,3,7,8-TCDD as a probable carcinogen for humans.(1)
In humans, 2,3,7,8-TCDD causes chloracne, a severe rash that usually occurs on the head and upper body. There is also evidence the 2,3,7,8-TCDD causes liver damage, loss of appetite, weight loss, and digestive disorders. The human carcinogenicity of dioxin is being reviewed by EPA and the authors have used cancer slope factors which have been established for some time. The EPA review may change the results of these estimates.
The MRL for dioxin was exceeded in the scenarios for a child playing in off-site residential soil, a child trespassing onto the site one day per week, and by the adult worker five days per week. Cancer risk was estimated to be "no apparent increased risk" for off-site residential soil, and "moderate increased risk" for workers at the facility for 20 years. The lagoon water and soil scenarios disclosed "no increased risk" of cancer.
B. Health Outcome Data Evaluation
There are no health outcome databases available which include expected rates of the reported health effects in residents living near the site. Therefore, evaluation of health outcome data was limited to evaluation of the residential survey.
On the residential survey, one or more residents/households circled the following choices listed
under "chronic health problems" on the survey forms:
| respiratory migraines skin rash kidney bladder |
reproductive neurological stomach disorders nose or throat |
Other symptoms or health conditions listed by residents at least once included:
| colds lumps in armpits acne-like lesions miscarriage vaginal hemorrhage cramping hysterectomy breast and uterine tumors |
pneumonia flu chloracne ear infections throat and lung cancer slow growth no weight gain liver problems bronchitis |
The results of the residential survey were evaluated by WDOH. WDOH suggested changes to the format of the survey form, but the changes were not incorporated before information was collected. The 19 households included in the survey were selected by the resident who administered the survey and included residents who lived in the nearby apartment complex, in houses in the neighborhood, or had formerly lived in the neighborhood.
Due to the following limitations, the data are difficult to interpret:
C. Community Health Concerns Evaluation
The community health concerns which were conveyed to WDOH included the data/information reported in resident surveys and resident interviews. Concerns about human activity at the drainage lagoon were submitted by the local health district.
As we have reported in the Public Health Implications section, using the information provided, there were no non-cancer risk health effects displayed in the scenarios for PCP or PAHs. There was some slight risk displayed for dioxin for a child in the residential and on-site scenarios. There were no health effect risks displayed in the lagoon scenarios.
Only two effects of dioxin exposure have been confirmed in humans, chloracne and transient mild hepatotoxicity. Many other effects have been studied but have not been confirmed. Most cases of chloracne resolve in one to three years. Victims of industrial accidents have been the main human study groups. From those studies it appears that 9.7 ug, as measured in adipose tissue, may the lowest observable adverse effect level for dioxin related chloracne in humans. Although dioxins have produced neurotoxic results in laboratory animals, data from human studies have been inconsistent and inconclusive. Hepatotoxicity has been observed in a variety of animals, but there is no evidence that TCDD causes long-term hepatotoxicity in humans. Studies of an industrial accident exposed population failed to demonstrate increased risk of birth defects due to dioxin exposure. (6)
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