ADDENDUM TO PUBLIC HEALTH ASSESSMENT
UNITED CREOSOTING COMPANY
CONROE, MONTGOMERY COUNTY, TEXAS
ENVIRONMENTAL CONTAMINATION AND OTHER HAZARDS
The tables in this section contain a list of the contaminants of concern. We evaluate these contaminants in subsequent sections of this health assessment addendum, and we determine whether or not exposure to them has public health significance. ATSDR selects contaminants based upon the following factors:
In the data tables that follow the title "On-site Contamination,"
the fact that a contaminant is listed does not mean that exposure
will cause adverse health effects. Instead, the list indicates
which contaminants will be evaluated further in the health
assessment addendum. When selected as a contaminant of concern
in one medium, that contaminant will be reported in all media.
The data tables include the following acronyms:
| = Environmental Media Evaluation Guide | |
| = Environmental Protection Agency Action Level | |
| = Health Assessment Comparison Value | |
| = Maximum Contaminant Level Goal | |
| = Minimal Risk Level | |
| = Not Detected | |
| = Proposed Maximum Contaminant Level Goal | |
| = Reference Dose |
ATSDR Health Assessment Comparison (HAC) values are contaminant concentrations for specific media. They are used to select contaminants for further evaluation. Those values include Environmental Media Evaluation Guides (EMEGs), and other relevant guidelines. In this health assessment addendum, EPA-AL are EPA health-based action levels for mixtures of carcinogenic polycyclic aromatic hydrocarbons (PAHs) and carcinogenic dioxin and furan mixtures. The carcinogenic PAHs have been converted into benzo(a)pyrene equivalents and summed as total benzopyrene equivalents. The carcinogenic dioxins and furans have been converted to 2,3,7,8-tetrachlorodibenzodioxin (TCDD) equivalents and summed as total TCDD equivalents. EPA's Maximum Contaminant Level Goal (MCLG) is a drinking water health goal. EPA believes that the MCLG represents a level at which no known or anticipated adverse effect on the health of persons should occur, and which allows an adequate margin of safety. Proposed Maximum Contaminant Level Goals (PMCLGs) are MCLGs that are being proposed. The MRL is an estimate of daily human exposure to a contaminant below which adverse, non-cancerous health effects are unlikely to occur. EPA's Reference Dose (RfD) is an estimate of the daily exposure to a contaminant that is unlikely to cause adverse health effects.
We conducted a search of the Toxic Chemical Release Inventory (TRI) for the site and for the zip code area of the site. Reported releases included 20 different compounds from a total of three facilities, none of which are on site. None of the reported chemical releases are the same compounds as the contaminants of concern identified at the United Creosoting Company site.
The environmental media sampling events discussed in this health assessment addendum were conducted in two phases. Sampling for the remedial investigation took place between December 1984 and August 1985. Those environmental data were evaluated in the health assessment, but will be reviewed in more detail in this addendum. In 1990, field sampling was conducted for the supplemental site investigation. During initial sampling activities, soil, surface water, ground water, biota, and air samples were collected. The supplemental field sampling was designed to fill in existing data gaps and to facilitate remediation.
The on-site area includes the Tanglewood East subdivision, Sisco Construction, Clarke Distributing Company, and a vacant area at the southeastern corner of the original site. Contaminants of concern identified during sampling activities were polycyclic aromatic hydrocarbons (PAHs), chlorinated dibenzodioxins/ dibenzofurans (CDD/CDFs), and pentachlorophenol. The most toxic chlorinated dioxin, 2,3,7,8-tetrachlorodibenzo-dioxin, was not found at the site.
Surface soil
Surface soil samples (0 to 6 inches) were taken at 83 locations in the 1984-1985 sampling effort, and at 59 sampling locations in the 1990 sampling event. The highest concentrations of surface soil contamination were found along the Tanglewood East - Clarke Distributing property line. That area corresponds to the United Creosoting Company's former processing areas. High concentrations of surface soil contamination were also characterized by the presence of "tar mats" (accumulations of asphaltic wastes), and stained soils. Elevated levels of PAHs to 2800 mg/kg and pentachlorophenol to 150 mg/kg, were detected in residential surface soils in 1984-1985 (see Table 1). Those areas are near the former waste ponds and along the fence line between the vacant area and the Tanglewood East subdivision. Surface soil in a vacant lot in the Griffith Street cul-de-sac contained the highest level of total PAHs with 15,750 mg/kg. Less surface-soil contamination was detected in the industrial areas than in the residential areas in the 1984-1985 sampling (Table 2).
In 1990 sampling, total carcinogenic PAHs and total carcinogenic
CDD/CDFs were calculated for each soil sample taken. The results
of each carcinogenic PAH found was converted into benzo(a)pyrene
equivalents and summed to obtain total benzopyrene equivalents.
The carcinogenic CDD/CDFs were converted into
2,3,7,8-tetrachlorodibenzodioxin (TCDD) equivalents.
TABLE 1
ON-SITE RESIDENTIAL 1984-1985 SOIL SAMPLING DATA
UNITED CREOSOTING COMPANY*
| CHEMICAL NAME |
SURFACE SOIL (0-6 inches) mg/kg |
SUBSURFACE SOIL (2-12 feet) mg/kg |
HAC VALUE mg/kg |
HAC SOURCE |
| Pentachlorophenol (PCP) |
ND - 150 | ND - 65 | 100 | EMEG |
| POLYCYCLIC AROMATICS (PAHS) 2-methylnaphthalene |
ND | ND - 460 | NONE | NONE |
| Acenaphthene | ND - 2600 | ND - 220 | 3,000 | RfD |
| Anthracene | ND - 970 | ND - 160 | 15,000 | RfD |
| Dibenzofuran | ND | ND - 210 | NONE | NONE |
| Fluoranthene | ND - 700 | ND - 190 | 2,000 | RfD |
| Fluorene | ND - 84 | ND - 260 | 2,000 | RfD |
| Naphthalene | ND | ND - 620 | 200 | RfD |
| Phenanthrene | ND - 970 | ND - 1800 | 5,000 | RfD |
| Pyrene | ND - 2800 | ND - 340 | 1,500 | RfD |
| CARCINOGENIC PAHS 3,4-Benzo(b)fluoranthene |
ND - 1700 | ND - 34 | 5,000 | MRL |
| Benzo(a)anthracene | ND - 2000 | ND - 50 | 5,000 | MRL |
| Benzo(a)pyrene | ND - 650 | ND - 32 | 5,000 | MRL |
| Benzo(g,h,i)perylene | ND - 84 | ND - 0.56 | 5,000 | MRL |
| Benzo(k)fluoranthene | ND - 1700 | ND - 140 | 5,000 | MRL |
| Chrysene | ND - 2000 | ND - 50 | 5,000 | MRL |
| CHLORINATED DIOXINS Tetrachlorodibenzodioxin |
ND - 0.00036 | ND - 0.00042 | 0.00005 | MRL |
| Pentachlorodibenzodioxin | ND - 0.0073 | ND - 0.0016 | NONE | NONE |
| Hexachlorodibenzodioxin | ND - 0.0076 | ND - 0.27 | NONE | NONE |
| Heptachlorodibenzodioxin | ND - 0.720 | 0.0022 - 0.520 | NONE | NONE |
| Octachlorodibenzodioxin |
0.0049 - 6.0 | 0.0077 - 1.050 | NONE | NONE |
| CHLORINATED DIBENZOFURANS Hexachlorodibenzofuran |
ND - 0.140 | ND - 0.021 | NONE | NONE |
| Heptachlorodibenzofuran | ND - 0.890 | ND - 0.790 | NONE | NONE |
| Octachlorodibenzofuran | ND - 1.50 | ND - 0.500 | NONE | NONE |
TABLE 2
ON-SITE INDUSTRIAL 1984-1985 SOIL SAMPLING DATA
UNITED CREOSOTING COMPANY*
| CHEMICAL NAME |
SURFACE SOIL (0-6 inches) mg/kg |
SUBSURFACE SOIL (2-20 feet) mg/kg |
HAC VALUE mg/kg |
HAC SOURCE |
| Pentachlorophenol (PCP) |
ND - 26 | ND - 1100 | 100 | EMEG |
| POLYCYCLIC AROMATICS (PAHS) 2-methylnaphthalene |
ND - 260 | ND - 940 | NONE | NONE |
| Acenaphthene | ND - 210 | ND - 860 | 3,000 | RfD |
| Anthracene | ND - 6.3 | ND - 280 | 15,000 | RfD |
| Dibenzofuran | ND - 250 | ND - 930 | NONE | NONE |
| Fluoranthene | ND - 220 | ND - 980 | 2,000 | RfD |
| Fluorene | ND - 280 | ND - 1100 | 2,000 | RfD |
| Naphthalene | ND - 130 | ND - 1200 | 200 | RfD |
| Phenanthrene | ND - 1500 | ND - 7400 | 5,000 | RfD |
| Pyrene |
ND - 370 | ND - 1600 | 1,500 | RfD |
| CARCINOGENIC PAHS 3,4-Benzo(b)fluoranthene |
ND - 24 | ND - 7.7 | 5,000 | MRL |
| Benzo(a)anthracene | ND - 36 | ND - 180 | 5,000 | MRL |
| Benzo(a)pyrene | ND - 38 | ND - 5 | 5,000 | MRL |
| Benzo(g,h,i)perylene | ND - 12 | ND - 5.3 | 5,000 | MRL |
| Benzo(k)fluoranthene | ND - 24 | ND - 24 | 5,000 | MRL |
| Chrysene |
ND - 6.3 | ND - 130 | 5,000 | MRL |
| CHLORINATED DIOXINS Tetrachlorodibenzodioxin |
ND | ND - 0.00531 | 0.00005 | MRL |
| Pentachlorodibenzodioxin | ND - 0.00125 | ND - 0.021 | NONE | NONE |
| Hexachlorodibenzodioxin | 0.0013 - 0.030 | ND - 0.007 | NONE | NONE |
| Heptachlorodibenzodioxin | 0.033 - 0.350 | ND - 0.410 | NONE | NONE |
| Octachlorodibenzodioxin |
0.0077 - 0.63 | ND - 0.240 | NONE | NONE |
| CHLORINATED DIBENZOFURANS Hexachlorodibenzofuran |
ND - 0.047 | ND - 0.018 | NONE | NONE |
| Heptachlorodibenzofuran | 0.0057 - 0.150 | ND - 0.037 | NONE | NONE |
| Octachlorodibenzofuran | 0.0053 - 0.180 | ND - 0.012 | NONE | NONE |
Elevated levels of total carcinogenic PAHs were found in the residential areas on site that ranged up to 84 mg/kg (benzo(a)pyrene equivalents) (See Table 3). Fourteen residential surface samples exceeded the EPA residential health action levels for carcinogenic PAHs. These elevated samples were scattered, although the highest number of samples were taken between Arlington and Brewster Streets and between Columbia and Darnell Streets. Nine of the elevated samples were taken near the fence line separating the residential and industrial areas.
Elevated levels of total carcinogenic CDD/CDFs were found in residential areas on site that ranged up to 0.016 mg/kg (TCDD equivalents). Several residential surface samples exceeded the EPA residential health action level for carcinogenic CDD/CDFs. Five of those samples were taken around residences near the fence line separating the residential and industrial areas. The other two soil samples were taken between Columbia and Darnell Streets. In the industrial areas, no surface soil samples exceeded the EPA action levels for CDD/CDFs or for carcinogenic PAHs (Table 4). Pentachlorophenol was detected up to 510 mg/kg in the industrial areas.
As part of the 1984-1985 sampling activities, vacuum cleaner bags, air conditioner filters, and wipe samples were collected from five homes. In addition, wipe samples were collected at ten locations from structures at Sisco Construction and Clarke Distributing. Semivolatile organics were not detected in any wipe samples or vacuum cleaner bags taken from residences. Air conditioner filters were tested for CDD/CDFs. CDD/CDFs were detected in samples taken from three homes, but at levels near detection limits. Industrial wipe samples were negative for semi-volatile organics with the exception of one sample. That sample contained CDD/CDF and pyrene. Visual inspection indicated that the sample was from creosoted lumber remaining from the United Creosoting Company.
Subsurface soil
Subsurface soil samples were collected from depths of one foot to
25 feet. Data collected during the remedial investigation
indicate the presence of contamination in two main locations.
One elevated contaminant concentration is underneath the former
site of the tank pond and coal tar distillation unit. The area
lies at the southern boundary of the Sisco Construction property,
with a portion lying on Clarke Distributing property. The second
area of elevated contaminant levels is mainly within the
northwestern corner of Clarke Distributing property, in the
former location of the waste ponds. In both locations in
TABLE 3
ON-SITE RESIDENTIAL 1990 SOIL SAMPLING DATA
UNITED CREOSOTING COMPANY1
| CHEMICAL NAME |
SURFACE SOIL (0-6 inches) mg/kg |
SUBSURFACE SOIL (1-5 feet) mg/kg |
HAC VALUE mg/kg |
HAC SOURCE |
| Pentachlorophenol (PCP) |
ND - 37 | ND - 93 | 100 | EMEG |
| POLYCYCLIC AROMATICS (PAHS) 2-methylnaphthalene |
ND | ND - 7.3 | NONE | NONE |
| Acenaphthene | ND - 0.67 | ND - 34 | 3,000 | RfD |
| Anthracene | ND - 710 | ND - 41 | 15,000 | RfD |
| Dibenzofuran | ND - 21 | ND - 15 | NONE | NONE |
| Fluoranthene | ND - 110 | ND - 260 | 2,000 | RfD |
| Fluorene | ND - 73 | ND - 35 | 2,000 | RfD |
| Naphthalene | ND - 0.076 | ND - 12 | 200 | RfD |
| Phenanthrene | ND - 160 | ND - 86 | 5,000 | RfD |
| Pyrene |
ND - 160 | ND - 160 | 1,500 | RfD |
| CARCINOGENIC PAHS (total) | ND - 84.02 | ND - 25.42 | 0.333 | EPA-AL |
| 3,4-Benzo(b)fluoranthene | ND - 11 | ND - 41 | 5,000 | MRL |
| Benzo(a)anthracene | ND - 35 | ND - 73 | 5,000 | MRL |
| Benzo(a)pyrene | ND - 72 | ND - 29 | 5,000 | MRL |
| Benzo(g,h,i)perylene | ND - 38 | ND - 10 | 5,000 | MRL |
| Benzo(k)fluoranthene | ND - 130 | ND - 0.72 | 5,000 | MRL |
| Chrysene | ND - 97 | ND - 34 | 5,000 | MRL |
| Dibenzo(a,h)anthracene | ND - 12 | ND - 5.5 | 5,000 | MRL |
| Ideno(1,2,3-cd)pyrene |
ND - 36 | ND - 11 | 5,000 | MRL |
| TOTAL DIOXINS/FURANS |
0.0000017 - 0.0164 | ND - 0.00234 | 0.0013 | EPA-AL |
| CHLORINATED DIOXINS Tetrachlorodibenzodioxin |
ND | ND | 0.00005 | MRL |
| Pentachlorodibenzodioxin | ND - 0.004 | ND | NONE | NONE |
| Hexachlorodibenzodioxin | ND - 0.203 | ND - 0.025 | NONE | NONE |
| Heptachlorodibenzodioxin | ND - 1 | ND - 0.247 | NONE | NONE |
| Octachlorodibenzodioxin |
ND - 2.8 | ND - 1.79 | NONE | NONE |
| CHLORINATED DIBENZOFURANS Tetrachlorodibenzofuran |
ND | ND - 0.037 | NONE | NONE |
| Pentachlorodibenzofuran | ND - 0.003 | ND - 0.16 | NONE | NONE |
| Hexachlorodibenzofuran | ND - 0.053 | ND - 0.087 | NONE | NONE |
| Heptachlorodibenzofuran | ND - 0.137 | ND - 0.211 | NONE | NONE |
| Octachlorodibenzofuran | ND - 0.420 | ND - 0.499 | NONE | NONE |
1 From Weston, 1990 as reported in the Site Investigation, 1990.
2 Expressed as Benzo(a)pyrene Equivalents
3 Screening level applies to residential surface soil
4 Dioxins and furans are expressed as 2,3,7,8 - TCDD Equivalents
TABLE 4
ON-SITE INDUSTRIAL 1990 SOIL SAMPLING DATA
UNITED CREOSOTING COMPANY1
| CHEMICAL NAME |
SURFACE SOIL (0-6 inches) mg/kg |
SUBSURFACE SOIL (2-20 feet) mg/kg |
HAC VALUE mg/kg |
HAC SOURCE |
| Pentachlorophenol (PCP) |
ND - 510 | ND - 96 | 100 | EMEG |
| POLYCYCLIC AROMATICS (PAHS) 2-methylnaphthalene |
ND | ND - 32 | NONE | NONE |
| Acenaphthene | ND - 99 | ND - 220 | 3,000 | RfD |
| Anthracene | ND - 92 | ND - 100 | 15,000 | RfD |
| Dibenzofuran | ND | ND - 190 | NONE | NONE |
| Fluoranthene | ND - 710 | ND - 220 | 2,000 | RfD |
| Fluorene | ND - 71 | ND - 190 | 2,000 | RfD |
| Naphthalene | ND | ND - 67 | 200 | RfD |
| Phenanthrene | ND - 820 | ND - 480 | 5,000 | RfD |
| Pyrene |
ND - 610 | ND - 620 | 1,500 | RfD |
| CARCINOGENIC PAHS (total) | ND - 2.182 | ND - 0.2172 | 403 | EPA-AL |
| Benzo(a)anthracene | ND - 150 | ND - 34 | 5,000 | MRL |
| Benzo(a)pyrene | ND - 38 | ND - 13 | 5,000 | MRL |
| Benzo(b)fluoranthene | ND - 100 | ND - 18 | 5,000 | MRL |
| Benzo(g,h,i)perylene | ND - 0.800 | ND - 4.4 | 5,000 | MRL |
| Benzo(k)fluoranthene | ND | ND - 13 | 5,000 | MRL |
| Chrysene | ND - 140 | ND - 35 | 5,000 | MRL |
| Dibenzo(a,h)anthracene | ND | ND - 0.570 | 5,000 | MRL |
| Ideno(1,2,3-cd)pyrene |
ND - 0.530 | ND - 5.6 | 5,000 | MRL |
| TOTAL DIOXINS/FURANS | 0.0000049 - 0.007034 |
ND - 0.001184 | 0.023 | EPA-AL |
| CHLORINATED DIOXINS Tetrachlorodibenzodioxin |
ND | ND | 0.00005 | MRL |
| Pentachlorodibenzodioxin | ND | ND | NONE | NONE |
| Hexachlorodibenzodioxin | ND - 0.041 | ND - 0.003 | NONE | NONE |
| Heptachlorodibenzodioxin | ND - 0.437 | ND - 0.072 | NONE | NONE |
| Octachlorodibenzodioxin |
0.005 - 1.32 | ND - 0.383 | NONE | NONE |
| CHLORINATED DIBENZOFURANS Tetrachlorodibenzofuran |
ND | ND | NONE | NONE |
| Pentachlorodibenzofuran | ND - 0.002 | ND | NONE | NONE |
| Hexachlorodibenzofuran | ND - 0.037 | ND - 0.005 | NONE | NONE |
| Heptachlorodibenzofuran | ND - 0.168 | ND - 0.046 | NONE | NONE |
| Octachlorodibenzofuran | ND - 0.500 | ND - 0.066 | NONE | NONE |
1984-1985, elevated levels of pentachlorophenol (up to 1100 mg/kg), naphthalene (up to 1200 mg/kg), and pyrene (up to 1600 mg/kg) were identified. Tables 1 through 4 show the ranges of contaminants found in on-site subsurface soil in residential and industrial areas.
Sediment
Sediment samples were collected from five locations during 1984-1985 sampling. One of the five locations was less than 200 feet off site and downstream. At each sample location, three separate samples were taken: one stream bed composite, one bank composite, and one over-bank composite. Table 5 shows the ranges of contaminants found in on-site sediment samples. Samples from three locations in the now vacant industrial area contained several contaminants of concern including pentachlorophenol, PAHs, and CDD/CDFs.
Samples taken from Alligator Creek did not show evidence of contamination.
Ground Water
Ground water sampling was conducted during the 1984-1985 sampling event. The map in Appendix D shows the locations of the monitoring wells. The ground water sampling conducted at that time used fourteen existing shallow monitoring wells to determine ground water flow direction and the extent of the contamination into the shallow water-bearing zones. The shallow water-bearing zones include the unconfined (20-40 feet) and semi-confined (40-60 feet) zones. Also, 15 new monitoring wells were installed in the shallow zones. Table 6 shows the levels of contamination found in the shallow water-bearing zones.
Well data collected from the shallow unconfined zone showed
semi-volatile organic contamination near the former waste ponds,
with migration to a point 800 feet southwest of the pond. The
highest levels of PAHs were found in a monitoring well on the
southeastern end of Brewster Street near the fence line
separating the residential and industrial areas. The
semi-confined zone lies directly beneath the shallow unconfined
water-bearing zone. Data from a monitoring well that is on the
north side of Clarke Distributing near a former waste pond, and
which is within the shallow semi-confined zone, showed
contamination with semi-volatile organics, including naphthalene
TABLE 5
ON-SITE ENVIRONMENTAL 1984-1985 SEDIMENT SAMPLING DATA*
UNITED CREOSOTING COMPANY
| CHEMICAL NAME | SEDIMENT SAMPLES (0-0.5 feet) mg/kg |
HAC VALUE mg/kg |
HAC SOURCE | |
| Pentachlorophenol (PCP) |
ND - 38 | 100 | EMEG | |
| POLYCYCLIC AROMATICS (PAHS) 2-methylnaphthalene |
ND | NONE | NONE | |
| Acenaphthene | ND | 3,000 | RfD | |
| Anthracene | ND - 75 | 15,000 | RfD | |
| Dibenzofuran | ND | NONE | NONE | |
| Fluoranthene | ND - 150 | 2,000 | RfD | |
| Fluorene | ND | 2,000 | RfD | |
| Naphthalene | ND | 200 | RfD | |
| Phenanthrene | ND - 11 | 5,000 | RfD | |
| Pyrene |
ND - 120 | 1,500 | RfD | |
| CARCINOGENIC PAHS 3,4-Benzo(b)fluoranthene |
ND - 150 | 5,000 | MRL | |
| Benzo(a)anthracene | ND - 77 | 5,000 | MRL | |
| Benzo(a)pyrene | ND - 68 | 5,000 | MRL | |
| Benzo(g,h,i)perylene | ND - 38 | 5,000 | MRL | |
| Benzo(k)fluoranthene | ND - 150 | 5,000 | MRL | |
| Chrysene |
ND - 75 | 5,000 | MRL | |
| CHLORINATED DIOXINS Tetrachlorodibenzodioxin |
ND | 0.00005 | MRL | |
| Pentachlorodibenzodioxin | ND - 0.00040 | NONE | NONE | |
| Hexachlorodibenzodioxin | ND - 0.015 | NONE | NONE | |
| Heptachlorodibenzodioxin | ND - 0.240 | NONE | NONE | |
| Octachlorodibenzodioxin |
ND - 0.400 | NONE | NONE | |
| CHLORINATED DIBENZOFURANS Hexachlorodibenzofuran |
ND - 0.010 | NONE | NONE | |
| Heptachlorodibenzofuran | ND - 0.037 | NONE | NONE | |
| Octachlorodibenzofuran | ND - 0.027 | NONE | NONE | |
TABLE 6
ON-SITE ENVIRONMENTAL 1984-1985 GROUND-WATER SAMPLING DATA*
UNITED CREOSOTING COMPANY
| CHEMICAL NAME | GROUND WATER (ug/L) |
HAC VALUE ug/L |
HAC SOURCE | |
| Pentachlorophenol (PCP) |
ND - 220 | 20 | EMEG | |
| POLYCYCLIC AROMATICS (PAHS) 2-methylnaphthalene |
ND - 750,000 | NONE | NONE | |
| Acenaphthene | ND - 490,000 | 600 | RfD | |
| Anthracene | ND - 140,000 | 3,000 | RfD | |
| Dibenzofuran | ND - 410,000 | ONE | NONE | |
| Fluoranthene | ND - 280,000 | 400 | RfD | |
| Fluorene | ND - 410,000 | 400 | RfD | |
| Naphthalene | ND - 1,200,000 | 40 | RfD | |
| Phenanthrene | ND - 830,000 | 1,000 | MRL | |
| Pyrene | ND - 450,000 |
300 | RfD | |
| CARCINOGENIC PAHS 3,4-Benzo(b)fluoranthene |
ND | 0.2 | PMCL | |
| Benzo(a)anthracene | ND | 0.1 | PMCL | |
| Benzo(a)pyrene | ND | 0.2 | PMCL | |
| Benzo(g,h,i)perylene | ND | 1,000 | PMCL | |
| Benzo(k)fluoranthene | ND | 0.2 | PMCL | |
| Chrysene |
ND | 0.2 | PMCL | |
| CHLORINATED DIOXINS Tetrachlorodibenzodioxin |
ND | 0.00005 | PMCL | |
| Pentachlorodibenzodioxin | ND - 0.0018 | NONE | NONE | |
| Hexachlorodibenzodioxin | ND - 0.0029 | NONE | NONE | |
| Heptachlorodibenzodioxin | ND - 0.066 | NONE | NONE | |
| Octachlorodibenzodioxin |
ND - 0.48 | NONE | NONE | |
| CHLORINATED DIBENZOFURANS Hexachlorodibenzofuran |
ND | NONE | NONE | |
| Heptachlorodibenzofuran | ND | NONE | NONE | |
| Octachlorodibenzofuran | ND | NONE | NONE | |
up to 2,000 µ/L, and pentachlorophenol up to 180 µ/L. Weston estimated that the plume of ground water contamination extends upto 1,400 feet to the south of the former waste ponds in the shallow semi-confined zone. Five monitor wells were installed in the lower water-bearing zone (60-80 feet). No semivolatile contaminants were found in this water zone. There are reported to be at least 60 wells used for domestic and public drinking water, and for industrial purposes within two miles downgradient from the site. All were screened at a minimum of 66 feet, with most being screened at 100 feet or more.
Surface water
Storm water run-off samples were collected on December 4, 1984, and stream flow samples were collected on December 10, 1984. No semi-volatile organic contaminants were detected in the site run-off samples. Pentachlorophenol was detected (14 µ/L) at one surface-water sampling location. That sample was taken from a pool of water standing in a ditch containing contaminated soils in the now vacant Clarke area.
Air
Air monitoring was conducted in two steps. On October 1, 1984, before any site activities, baseline levels were determined with a portable organic vapor analyzer (OVA). Volatile organics were not detected in any part of the site, including areas of apparent contamination. Ambient air monitoring was also conducted upwind and downwind of the site on two separate occasions. Sampling conducted on December 2, 1984 provided a baseline before soil disruption. On December 12, 1984, air sampling was conducted while boring into the former waste ponds. During both sampling events, samples were collected at three locations, one upgradient and two downgradient. Air monitoring was also conducted in association with field drilling activities to determine possible contaminant releases during subsurface soil disturbances. All samples were analyzed for volatile organic peaks with the OVA. None of the samples produced peaks significantly above ambient levels; therefore, no air monitoring samples were analyzed in a laboratory.
Biota
A vegetation survey and tree core analyses were completed in conjunction with 1984 site investigation sampling activities. Tree cores were taken from eleven loblolly pines on site and ten loblolly pines off site. On-site vegetation showed signs of stress in areas directly south of the Clarke Distributing complex. Tree core data indicated that on-site trees were considerably shorter than corresponding off-site trees of the same species and age. In both samples, the estimated ages of the trees were taken into account when comparing heights.
Sampling of crawfish took place at three locations, one of which was upstream from the site. Attempts to sample minnows were unsuccessful. Semi-volatile organic analyses showed results below detection limits in all crawfish samples, but the detection limits were high (11-22 mg/kg). According to Weston, the high detection limits probably resulted from the presence of other naturally occurring organics within crawfish tissue.
A very limited number of off-site samples were taken: two soil samples, one sediment sample, one surface-water sample, ground- water samples at two upgradient locations, and four ambient air samples for volatile organic compounds (VOCs). No contamination was detected in those samples. Contamination was visible on site and significantly decreased away from the process area. The contaminated portion of the site itself comprises about 20 to 30 acres of land used intensively for wood treatment processing and storage. The remainder of the original 100-acre tract was densely wooded and undisturbed until the development of the Tanglewood East subdivision.
C. QUALITY ASSURANCE AND QUALITY CONTROL
In 1984-1985, all analyses for semi-volatile organics and the CDD/CDFs were carried out in accordance with the project Quality Assurance/Quality Control (QA/QC) Plan, according to the Final Site Investigation Report. The analytical laboratories ran such internal QA/QC checks as daily calibrations and spike recovery. Spikes are known amounts of specific chemical constituents added by the laboratory to selected samples to test the appropriateness and to recover efficiencies of specific analytical methods. External QA/QC checks were made by the field team through the submittal to the laboratory of known sample entities, such as duplicates and blanks, without informing the laboratory of the nature of the sample. Duplicates are identical splits of individual samples that are analyzed by the laboratory to test for method reproducibility. A sample management system was implemented to track all samples at all times and to assure that recommended sample holding times were not exceeded.
In 1990 sampling, an overall comprehensiveness goal of 90% was established for the project. The overall comprehensiveness included the following:
The overall project comprehensiveness was about 88.5%, mainly because hold times were exceeded for approximately 17% of the samples analyzed for CDD/CDFs. According to the Data Evaluation Report of the Focused Site Investigation, the results for those chemicals were used with reservation. The report indicated that since CDD/CDFs tend to degrade very slowly over time, the concentrations of those chemicals will not change significantly over time.
During the January 21, 1991, site visit, teen-age boys were
observed climbing the privacy fence into the area from which the
six homes had been removed. Despite the presence of signs,
locks, and a eight-foot privacy fence, trespassers are an ongoing
problem. In addition to the possible exposure risks,
trespassers may injure themselves while trying to climb the
fence. Other than the possible hazards outlined here, the
United Creosoting Company site appeared to be an unusually clean
and orderly site.
To determine if residents are exposed to contaminants on the site, ATSDR evaluates the environmental and human components that lead to human exposure. A pathway 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 identifies exposure pathways as completed, potential, or eliminated. Completed pathways require that the five elements exist, indicating that exposure to a contaminant has occurred, is occurring, or will occur. Potential pathways, however, require that at least one of the five elements be missing, but could come into being. Potential pathways indicate that exposure to a contaminant could have occurred already, could be occurring now, or could occur in the future. Eliminated pathways require that at least one of the five elements be missing and that it will never be present. Completed and potential pathways may also be classified as eliminated when they are unlikely to exist.
Data collected during environmental sampling identified levels of contamination in surface soil, subsurface soil, sediments, and shallow ground water. The main contaminants of concern are PAHs, pentachlorophenol, and CDD/CDFs. The United Creosoting Company site is on the western Gulf Coastal Plain, where soils were deposited in stream bed and deltaic formations during the Pleistocene era. The surface soils are in the Conroe and Splendora series and are underlain by the Willis sand formation. Those soils vary from gravelly sand to silty clays.
With the great variation in soil particle size, from coarse gravels to fine silt and clays, the potential for filtration, and adsorption and absorption of the contaminants onto the soil is extremely high. That has possibly minimized contaminant migration and may be responsible for the high levels of contamination in the 0 - 1.5 foot levels indicated by the soil sampling data.
Pentachlorophenol, PAH, and CDD/CDF contamination was found in surface and subsurface soils in on-site residential and industrial areas. That pathway will be discussed further in the Human Exposure Pathways section.
At this site, shallow ground water exists in two inter-connected zones of unconfined to semi-confined water-bearing sands. Below that, a clay layer functions as an aquitard. That aquitard limits communication between the two shallow water- bearing zones and any deeper aquifers. It also appears to act as a barrier for contaminant migration. The shallow water- bearing zones are not currently used as a water source, and due to their low productivity it is unlikely that they will be tapped in the future. Therefore, that potential exposure pathway can be eliminated because it is unlikely ever to exist.
The major aquifers below this site, in order of depth, are the Chicot, the Evangeline, and the Jasper. The Chicot and the Evangeline are heavily used as drinking water sources. Water quality in the Jasper is variable and only the upper portion is used as a source of drinking water. The semi-confined nature of the shallow water-bearing zone has made it possible to clearly define the extent of contamination through well logging, sampling and ground resonancing.
Pentachlorophenol is soluble in water and is present throughout the shallow water-bearing zone at levels as high as 220 µg/L. PAHs were detected up to 1,200,000 µg/L. PAHs have a high affinity for adsorption to soil particles. That is reflected by the significant decrease in concentrations of PAHs as the soil sampling depth increases. With ground water, the clay layer 30 to 40 feet below the site surface appears to have formed a barrier to the vertical migration of contaminants into the lower water-bearing zones. Due to soil adsorption characteristics, dilution of PAHs, and the low water solubility of creosote, contamination of the shallow water-bearing zones decreases as the distance from the waste ponds increases. Sampling indicates that the contaminant plume has migrated in a southwesterly direction approximately 800 feet in the unconfined zone, and approximately 1,400 feet in the semi-confined zone, but has not surfaced at any known location. The nearest municipal well is located one mile west-northwest of the site and is screened at 825-1190 feet. Therefore, it should not be impacted by this plume.
Vertical migration velocities were calculated to assess the potential for the downward flow of ground water through the confining clay layer. The number of years required for ground water to completely penetrate the clay was estimated at about 100 years. As a result of this analysis, there appears to be a low potential for downward vertical migration of contaminants from the shallow water-bearing zone to the lower water-bearing zone. Based on the topographic data, measured water table elevations, and slope of the shallow water bearing zone, it is unlikely that the shallow zone ground waters discharge into Alligator Creek.
Surface water drains to the southwest at the United Creosoting location. Surface water flows through the Tanglewood East subdivision and into Alligator Creek. Alligator Creek flows into the west fork of the San Jacinto River. No evidence of contaminant migration was present in surface water sampling conducted in the area of Alligator Creek. Therefore, that pathway can be eliminated.
Sediment samples from Alligator Creek showed no evidence of contaminant migration. Three sediment samples taken at the Clarke vacant area did show evidence of pentachlorophenol and PAH contamination. Those samples were taken from areas of visible contamination and where there was visible evidence of erosion. Further characterization of area sediments is necessary to determine the nature of contaminant migration by this route. According to EPA Region 6, they plan to take additional samples from the creek.
In 1990, an air pathway analysis was conducted to estimate the air quality impact of the remediation activities. The air pathway analysis uses a combination of modeling and/or monitoring methods to assess actual or potential contaminant exposure. Levels of concern were determined for each compound (for which an ambient concentration was estimated). These levels took in account sensitive populations and length of exposures. The resultant predicted maximum 24-hour and annual concentration exposures were at levels below concern for contaminants found at the United Creosoting Company site.
Bioaccumulation is a possible means of contaminant transport and accumulation, but probably not a significant environmental pathway at this site. PAHs are fat-soluble and can concentrate in fish and mammals, and to a limited extent in vegetation, especially aquatic vegetation. Data from crawfish sampling did not indicate the presence of contaminants. All results were below the 11 - 22 mg/kg detection levels, and similar levels were found for upstream and downstream samples. However, the detection limits for those samples were very high. Bioaccumulation is most significant for aquatic organisms and to a lesser extent for terrestrial plants and animals. No sampling was done to determine contaminant concentration and possible bioaccumulation in area plants.
PAHs can accumulate in terrestrial plants through the roots or foliage. Uptake rates depend on the concentrations, solubility, and molecular weights of the PAHs and the plant species. Ratios of PAH concentrations in vegetation to those in soil can range from 0.001 to 0.18 for total PAHs and from 0.002 to 0.33 for benzo(a)pyrene (Toxicological Profile for Polycyclic Aromatic Hydrocarbons ).
Very little information is available on plant uptake of pentachlorophenol, but one study indicated that lettuce grown on soil treated with pentachlorophenol contained residues of that chemical. No information could be found on plant uptake of the CDD/CDFs found on site, but limited data on 2,3,7,8-TCDD, a similar compound, indicate that this chemical does not bioaccumulate in crop plants. In one report, the edible portions of root vegetables contained much less 2,3,7,8-TCDD than the surrounding soils (Toxicological Profile for 2,3,7,8-Tetrachlorodibenzo-p-dioxin ).
Several human exposure pathways are possible due to the presence of contaminated media at and around the United Creosoting Company site. The potential exists for exposures to result from contact with contaminated surface soil, subsurface soil, and sediments. Human exposure resulting from dermal contact with contaminated soils and sediments is a pathway of concern. An additional potential exposure pathway is the ingestion of contaminated soil or plants. Ingestion of contaminated plants might have occurred in the past, but no sampling of vegetation was done in 1984-1985 or in 1990 to indicate whether or not contamination was present. Potentially exposed populations include remediation workers, area residents, and trespassers in restricted site locations.
The current public water supply does not draw from wells screened in the shallow water-bearing zone. Future human exposure pathways would be of concern if water from this zone were used for drinking. This is unlikely because the low yield of this aquifer makes it unsuitable for use, and water in the area is supplied by the city water system.
Primary exposure pathways from soil contamination include ingestion and dermal contact with contaminated soil. Surface soil contamination in areas of Tanglewood East subdivision provides a complete exposure pathway for area residents. Tracking contaminated soil into homes and into areas adjacent to the site may also occur. Populations at risk of exposure include area residents, remedial workers, and trespassers in restricted areas.
For remediation, contaminated soil in the residential area will
be excavated and moved to the industrial area, and the yards
replaced with clean fill. Contaminated soil in the industrial
area will be excavated and treated by a critical fluid extraction
system prior to being permanently placed under a cap in the
industrial area. Remedial activities will temporarily increase,
through excavation and movement of contaminated soils, the
potential for exposure of workers and trespassers through dermal
contact with exposed soils, ingestion of exposed soils, and
inhalation of contaminated dusts.
Introduction
In this section, we discuss the health effects in persons exposed to specific contaminants; evaluate state and local data bases, and address specific community health concerns. To evaluate health effects, ATSDR has developed a Minimal Risk Level (MRL) for contaminants commonly found at hazardous waste sites. The MRL is an estimate of daily exposure of persons to a contaminant below which non-cancerous, adverse health effects are unlikely to occur. MRLs are developed for each route of exposure, such as ingestion and inhalation, and for length of exposure, namely acute (less than 14 days), intermediate (15 to 364 days), and chronic (greater than 364 days). ATSDR presents the MRLs in its Toxicological Profiles series. Those chemical-specific profiles provide information on health effects, environmental transport, human exposure, and regulatory status. In the following discussion, we used ATSDR Toxicological Profiles for polycyclic aromatic hydrocarbons, pentachlorophenol, and 2,3,7,8-Tetrachlorodibenzo-p-dioxin.
Polycyclic Aromatic Hydrocarbons
Polycyclic aromatic hydrocarbons (PAHs) are a class of structurally related compounds. As a group, these compounds have similar characteristics.
Exposure to PAHs through ingestion of contaminated surface soils and skin contact with them may have occurred and may still be occurring among residents of the Tanglewood East subdivision and employees of Sisco Construction Company and Clarke Distributing. Using the highest total PAH concentration detected in residential surface soil (15,750 mg/kg), the ingestion exposure for adults and older children does not exceed ATSDR's acute MRL of 0.1 mg/kg/day for benzo(a)pyrene and other PAHs. The ingestion exposure for younger children (1 year through 6 years of age), does exceed the ATSDR MRL. That MRL, however, is based on an animal study in which developmental effects were seen in the offspring of mice following in utero exposure to benzo(a)pyrene. In determining the exposure doses, we assumed that younger children (16 kg) ingest 200 mg of soil per day; that older children (35 kg) ingest 100 mg of soil per day, and that adults (70 kg) ingest 50 mg of soil per day. Studies in animals have shown that PAHs can cause harmful effects on the liver and blood. The levels of PAHs at which those effects were first seen are 500-fold higher than the estimated dose for younger children. Therefore, the maximum level of PAHs found in the residential soil at Tanglewood East subdivision are unlikely to cause those effects in younger children at the estimated soil ingestion rate. ATSDR does not have MRLs for skin exposure to PAHs. For that reason, it is difficult to determine the health effects from skin exposure. Adverse skin effects have been noted in animals with acute and subchronic dermal exposures to PAHs. Those effects include destruction of sebaceous glands (glands in the skin which secrete fatty substances), skin ulcerations, hyperplasia (abnormal increase in number of skin cells), and overgrowth of the outer layer of the skin. Dermal exposure to certain PAHs, such as anthracene and phenanthrene, followed by exposure to sunlight may result in photoxic effects such as erythema (redness of the skin), urticaria (elevated patches of skin), and burning and itching. Persons with pre-existing skin conditions may be more sensitive to the adverse dermal effects of PAHs (ATSDR Toxicological Profile for Polycyclic Aromatic Hydrocarbons).
Several of the PAHs, including benzo(a)anthracene, benzo(a)pyrene, benzo(b)fluoranthene, benzo(k)fluoranthene, chrysene, dibenzo(a,h)anthracene, and ideno(1,2,3-cd)pyrene have caused tumors in laboratory animals through ingestion, skin contact, and inhalation. Epidemiologic studies of workers occupationally exposed to PAHs have provided limited evidence that PAH exposure may contribute to increased incidence of skin, lung, and genitourinary cancers. The most likely exposure routes in the occupational settings were through inhalation and skin contact with those compounds. Although inhalation of contaminated dusts is possible in the residential and industrial sections of the United Creosoting Company Site, that route of exposure is unlikely. Scientific data are insufficient at this time for determining whether cancer is possible from the ingestion of and skin contact with the levels of PAHs found in the surface soils at the United Creosoting Company Site. The levels of PAHs to which workers were exposed through skin contact in occupational studies are higher than the levels found in soils in the Tanglewood East Subdivision and on-site industrial areas.
Pentachlorophenol
Pentachlorophenol was detected in on-site surface and subsurface soils, sediment, and ground water. Residents in the Tanglewood East Subdivision and workers in the on-site industrial areas could have been and could be exposed to pentachlorophenol through ingestion of and skin contact with contaminated surface soils. The highest levels of pentachlorophenol in surface soils were 150 mg/kg in the residential area and 510 mg/kg in the industrial area. ATSDR has set an acute MRL of 0.05 mg/kg/day and an intermediate MRL of 0.002 mg/kg/day for pentachlorophenol. Based on the soil ingestion rates for adults and children discussed under PAHs and the highest levels of pentachlorophenol found, the ingestion exposures for adults and children do not exceed ATSDR's acute and intermediate MRLs. The estimated exposed doses also do not exceed EPA's chronic RfD of 0.03 mg/kg/day.
Animal studies have indicated that long-term exposure (greater than 14 days) to low levels of pentachlorophenol can have adverse effects on the liver, kidney, nervous system, and immune system. Studies have also indicated that long-term exposure to low levels of pentachlorophenol encountered in the workplace can cause damage to the liver, kidney, blood, and nervous system. The levels of pentachlorophenol found in the on-site areas at United Creosoting Company site are unlikely to result in those adverse health effects.
ATSDR could not locate any adequate studies that described significant levels of skin exposure to pentachlorophenol. Occupational exposures to pentachlorophenol have been associated with severe skin eruptions. Nonoccupational exposures to wood treated with pentachlorophenol have been associated with pemphigus vulgaris (a serious skin disease characterized by blisters and loss of skin) and chronic urticaria (a disorder of the skin characterized by itchy pink or white wheals). Skin effects discussed above may have resulted from impurities present in pentachlorophenol from the manufacture of this chemical (ATSDR Toxicological Profile for Pentachlorophenol ). The toxic dermal effects of pentachlorophenol appear to be most serious following high-dose, acute exposure.
Sufficient evidence exists from animal studies to suggest that pentachlorophenol might cause cancer in humans. No convincing evidence has been obtained from human epidemiological studies that indicate that pentachlorophenol causes cancer in humans. Case reports suggest a possible association between cancer (Hodgkin's disease, soft tissue sarcoma, and acute leukemia) and occupational exposure to technical pentachlorophenol that may have had other contaminants. Using animal studies, we estimate that residents who live in the Tanglewood East subdivision and were exposed to the highest levels of pentachlorophenol found in the residential area would have no increased risk of cancer. We estimate that workers who work in the on-site industrial areas would have no apparent increased risk of cancer from exposure to the highest level of pentachlorophenol detected in the industrial areas.
Chlorinated Dioxins/Dibenzofurans (CDDs/CDFs)
CDDs/CDFs were detected in on-site surface and subsurface soils, sediment, and ground water. According to the documents reviewed, the most toxic chlorinated dioxin, 2,3,7,8-tetrachlorodibenzo- p-dioxin (2,3,7,8-TCDD), was not detected at the United Creosoting Company site.
Residents in the Tanglewood East subdivision and workers in the on-site industrial areas could have been exposed and could be exposed to CDDs/CDFs through ingestion of and skin contact with contaminated surface soils. EPA has developed a procedure for estimating the relative potency of CDD/CDF mixtures compared to the potency of 2,3,7,8-TCDD by assigning each related compound a potency factor. The individual estimated potencies of the CDD/CDFs are summed to obtain total 2,3,7,8-TCDD equivalents. The toxicological information for 2,3,7,8-TCDD can then be applied to CDD/CDF mixtures.
ATSDR has set an acute MRL of 0.0000001 mg/kg/day and an intermediate MRL of 0.000000001 mg/kg/day for 2,3,7,8-TCDD. Based on the highest levels of CDD/CDFs (expressed as 2,3,7,8- TCDD equivalents) found in the on-site residential and industrial areas, the ingestion exposures for younger children slightly exceed ATSDR's acute MRL for 2,3,7,8-TCDD; ingestion exposures for older children and adults do not exceed ATSDR's acute MRL for that chemical. Ingestion exposures for both younger and older children and for adults exceed ATSDR's intermediate MRL for 2,3,7,8-TCDD.
Animal studies have indicated that 2,3,7,8-TCDD may cause liver damage; severe loss of body weight; damage to the immune system, and adverse reproductive effects including spontaneous abortions and malformations in animal offspring. Adverse effects of that chemical on the immune system, reproductive system and developing fetuses have not been found in humans, but some evidence has suggested that 2,3,7,8-TCDD might cause liver damage, weight loss, and digestive disorders in humans. Chloracne is the only confirmed effect in humans produced by certain compounds contaminated with 2,3,7,8-TCDD. Chloracne is a skin disease characterized by blackheads, cysts, pustules, and inflammatory (pain, redness, and swelling) skin changes of varying degrees of severity. A minimum toxic dose of 0.0001 mg/kg has been suggested to produce adverse noncancer health effects in humans (ATSDR Toxicological for 2,3,7,8-TCDD). Although the ingestion exposures for younger children exceed the acute MRL for 2,3,7,8-TCDD and the ingestion exposures for all age groups exceed the intermediate MRL for this chemical, all estimated exposures are well below the 0.0001 mg/kg level. Therefore, it is unlikely that residents and workers would develop skin, liver, or digestive disorders from past or present exposures to the maximum levels of CDD/CDFs found at the United Creosoting Company site. Results from animal studies clearly indicate that 2,3,7,8-TCDD causes cancer in laboratory animals. Several epidemiological studies of human populations exposed to herbicides contaminated with 2,3,7,8-TCDD have shown an association with cancer that included an increased incidence of soft tissue sarcomas, lymphomas, and stomach cancer. The evidence from human epidemiology studies is not conclusive because of inadequate exposure information and concomitant exposures to other chemicals. Other epidemiological studies have found no association between exposure to substances containing 2,3,7,8-TCDD and cancer.
Using animal studies, we estimate that residents who live in the Tanglewood East subdivision and who were exposed to the highest levels of CDD/CDFs (in TCDD equivalents) could have a low increased risk of developing cancer. While the number of extra cancers above the background cancer numbers might theoretically increase slightly, 2,3,7,8-TCDD induced cancers among residents in the Tanglewood East subdivision are unlikely to occur. In addition, the actual risk may be lower because (1) 2,3,7,8-TCDD other CDD/CDFs have not been shown to cause cancer in humans, (2) the risk estimate is based on a mathematical equation using assumptions that estimate the upper bound of risk, and (3) assumptions are used to estimate the maximum amount of exposure to CDD/CDFs (in TCDD equivalents).
We estimate that employees who work in on-site industrial areas would have no apparent increased risk of cancer.
B. HEALTH OUTCOME DATA EVALUATION
Guided by the concern of excessive cancer in Montgomery County, Texas, the TDH Environmental Epidemiology Program staff conducted an evaluation of cancer mortality in cooperation with the TDH Cancer Registry Division. Table 7 summarizes the results of that evaluation. For the years 1981-1989, the number of deaths from lung cancer among male and female residents in Montgomery County were slightly higher than expected, compared with statewide rates. For the same time period, a slight excess in the number of deaths from bladder cancer among males was also statistically significant. Standardized mortality ratios for those cancers were greater than 1.00, and the lower limits of the 95 per cent confidence limits exceeded 1.00.
The presented county data on cancer mortality may not be
representative of cancer mortality for the site population;
however, the health concern was expressed about the county
population. Census- and zip code-specific cancer mortality data
are not available through the TDH Bureau of Vital Statistics or
Table 7
Standardized Mortality Ratios* for Cancers of Selected Sites
Montgomery County Residents, Texas, 1981-89
| Site | Gender | Deaths Observed |
Deaths Expected |
Standardized Mortality Ratio |
95% Confidence Interval |
|
| Lung | Males | 472 | 389.05 | 1.23 | 1.12-1.35 | |
| Females | 232 | 168.62 | 1.37 | 1.20-1.56 |
||
| Skin | Males | 5 | 7.81 | 0.64 | 0.21-1.49 | |
| Females | 2 | 2.36 | 0.85 | 0.10-3.06 |
||
| Bladder | Males | 32 | 21.34 | 1.49 | 1.03-2.12 | |
| Females | 8 | 7.72 | 1.03 | 0.45-2.04 |
||
| Liver | Males | 15 | 19.43 | 0.77 | 0.43-1.27 | |
| Females | 12 | 11.33 | 1.05 | 0.55-1.85 |
||
| Breast | Males | -- | -- | -- | -- | |
| Females | 131 | 153.79 | 0.85 | 0.71-1.01 |
||
| Stomach | Males | 27 | 27.34 | 0.99 | 0.65-1.44 | |
| Females | 18 | 16.99 | 1.06 | 0.63-1.67 |
||
| Esophagus | Males | 28 | 22.03 | 1.27 | 0.84-1.84 | |
| Females | 6 | 6.65 | 0.90 | 0.33-1.96 |
||
| Leukemia | Males | 36 | 45.94 | 0.78 | 0.55-1.08 | |
| Females | 36 | 32.65 | 1.10 | 0.77-1.52 |
||
| Soft Tissue | Males | 10 | 7.97 | 1.25 | 0.60-2.30 | |
| Females | 7 | 7.18 | 0.97 | 0.39-2.01 |
||
| Non-Hodgkin's Lymphoma |
Males | 35 | 35.81 | 0.98 | 0.68-1.36 | |
| Females | 33 | 25.79 | 1.28 | 0.88-1.80 |
||
| Hodgkin's Disease | Males | 8 | 5.84 | 1.37 | 0.59-2.70 | |
| Females | 3 | 3.35 | 0.90 | 0.18-2.62 | ||
the Cancer Registry Division. Furthermore, data are not available on the potential roles that smoking and occupational exposures might have in the slight excesses of lung and bladder cancer mortality found among Montgomery County residents. Occupational exposures to PAH mixtures have been associated with lung and genitourinary cancers, but at exposures much higher than what would be encountered at the United Creosoting Company site.
C. COMMUNITY HEALTH CONCERNS EVALUATION
We have addressed each of the community concerns about health as follows.
Part of the 1990 Focused Site Investigation included air modeling to determine the effects that remediation might have on air quality. The air modeling effort indicated that air emissions during remediation will not be a health concern. According to EPA, remediation will be designed so as to minimize air emissions, and the area will be extensively monitored for air emissions. Also EPA has indicated that residents who are having their yards replaced, and residents adjacent to those yards, will be offered temporary relocation.
Air monitoring around on-site areas in 1984 did not indicate any significant presence of airborne contaminants. Temporary releases of volatile organics were noted during certain activities in which the soil was disturbed; but, none of the volatile organic peaks measured by the portable organic vapor analyzer were above ambient levels. An ambient air quality monitoring program will be established and operated throughout the site remediation. Dust control measures will be implemented throughout the activities to reduce the potential for releases of semi-volatiles and particulates. The presence of odors does not necessarily mean a contaminant is causing adverse health effects. In the future, odors are most likely to occur (if they occur at all) during site remediation activities involving excavation of soils. EPA has indicated that the necessary controls will be in place to prevent adverse health effects from air releases.
Some plants can take up PAHs through the roots or foliage. Ratios of PAH concentrations in vegetation to those in soil can range from 0.001 to 0.18 for total PAHs and from 0.002 to 0.33 for benzo(a)pyrene (ATSDR Toxicological Profile for Polycyclic Aromatic Hydrocarbons).
Limited data on 2,3,7,8-TCDD, which can be applied to the CDD/CDFs found at the United Creosoting site indicate that this chemical does not bioaccumulate in crop plants.
Pentachlorophenol may bioaccumulate in the food chain, but that chemical was not detected in most of the surface soil samples in the on-site residential area. Residents may want to review the results of their soil samples and contact TDH or ATSDR if they have questions about specific vegetables grown in their yards. Risk of exposure to site contaminants could vary from no risk to some risk depending on the levels of contaminants found in soils, the types of vegetables grown, and the frequency and amounts at which these vegetables are eaten. Once the soil is replaced in yards exceeding EPA's health action levels, any concerns about site contaminants accumulating in home-grown vegetables should be alleviated.
In the Section Toxicological Evaluation, exposure doses through ingestion of soil were estimated using the highest levels of contaminants found. Based on those exposure doses, acute health effects are unlikely to occur. Skin contact to any soil contaminants can be minimized by wearing water-resistant garden gloves and washing hands and any exposed skin with soap and water after contact with the soils. Residents whose surface soil samples in their yards exceed any of EPA's health action levels might want to further reduce their risk by avoiding digging in yard soil until it is replaced through remediation.
Several site contaminants including certain PAHs, pentachlorophenol, and possibly the chlorinated dioxins (if their skin effects are similar to 2,3,7,8-TCDD) have been associated with skin disorders. Reports of skin problems with these compounds have generally been with exposure to higher concentrations of the compounds than found in the residential surface soils at the United Creosoting Company NPL site. ATSDR does not have MRLs for skin exposure to PAHs, pentachlorophenol, or chlorinated dioxins. Therefore, it is difficult to predict the dermal effects from skin exposure to the site contaminants at the levels found at the United Creosoting Company NPL site. The specific skin problems that have been associated with exposure to PAHs, pentachlorophenol and chlorinated dioxins are discussed in the Toxicological Implications section of this Addendum.
As part of this Health Assessment Addendum, the ATSDR Health Activities Recommendations Panel (HARP) has reviewed the Addendum to determine appropriate follow-up activities. ATSDR has developed criteria to determine whether a health study should be conducted at a site and what type of study should be done. On September 11, 1991, this Addendum was reviewed by HARP for follow-up activities. ATSDR has determined that this site meets the criteria for both a disease and symptom prevalence study and site-specific surveillance activities.
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