HEALTH CONSULTATION
Exposure Investigation Report
CALCASIEU ESTUARY
LAKE CHARLES, CALCASIEU PARISH, LOUISIANA
Residents of the community of Mossville in Calcasieu Parish, Louisiana, expressed concern over potential health effects from exposure to chemical releases from chemical manufacturing plants in their neighborhood. To document their concerns, a private citizen provided ATSDR with blood dioxin test results that indicated that some residents of the Parish had elevated blood dioxin levels [1]. The individual with the highest dioxin level was a resident of Mossville.
In response to these preliminary findings, ATSDR conducted an Exposure Investigation (EI).
The purpose of the EI was to determine if there was evidence for increased exposure to dioxins in
residents of Mossville. Blood samples were collected from 28 residents of the community and
were analyzed for chlorinated dibenzodioxins (CDDs), chlorinated dibenzofurans (CDFs), and
co-planar polychlorinated biphenyls (PCBs). A limited investigation of environmental
contamination was also conducted: four surface soil samples and two chicken eggs were
collected and analyzed for CDDS and CDFs. A breast milk sample from one resident was also analyzed.
Calcasieu Parish contains a large number of chemical manufacturing plants that produce chemicals such as chlorinated hydrocarbon solvents, vinyl chloride monomer, and petroleum-based chemicals. Chemical wastes from some of these operations are burned in hazardous waste incinerators operated by industries in the area. Small amounts of CDDs and CDFs are reportedly formed during the production of vinyl chloride monomer [2]. The incineration of chlorinated hydrocarbon wastes can also produce CDDs and CDFs. The regeneration of catalysts used in petroleum refining is another potential source of CDDs and CDFs.
Mossville is located across the road from a large vinyl chloride monomer (VCM) plant. Several flares at this facility intermittently burn unidentified materials. A representative of the plant reported that the flares do not burn chlorinated hydrocarbons or other materials that contain chlorine. The plant also has two incinerators for chlorinated compounds that burn only gaseous vents from the VCM unit process. These incinerators have been sampled according to EPA methods and reportedly emit less than 0.1 grams of total dioxin per year.
ATSDR recently reviewed the results of a study in which blood dioxin levels were determined in 11 residents of Calcasieu Parish [1]. Three of the residents had blood dioxin levels that exceeded the reference range. The individual with the highest blood serum dioxin level (104 pg of dioxin TEQs/gram lipid or parts per trillion) was a resident of Mossville. This resident had no known occupational history of exposure to dioxins in the work place; therefore, it is suspected that this individual was exposed to dioxins from an unidentified environmental source.
In order to determine if other residents of Mossville have been exposed to dioxins, ATSDR conducted blood tests for dioxin-like compounds in residents of the community. In addition, surface soil and chicken egg samples were tested for dioxin contamination to identify possible sources of human exposure.
There are 75 congeners of CDDs and 125 congeners of CDFs. 2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) is the most toxic chemical in this group. Some of the other CDDs and CDFs (i.e., those with chlorine atoms in the 2,3,7,8 positions) have TCDD-like toxicity. In addition,
certain co-planar polychlorinated biphenyls (PCBs) have TCDD-like toxicity. Therefore, blood
samples were analyzed for CDDs, CDFs, and PCBs with TCDD-like activity. In this report,
"dioxin" or "dioxin like compounds" will be used as generic terms to refer to chemicals with TCDD-like toxicity.
Target Population
ATSDR solicited the participation of residents who live in Mossville in the area bounded by VCM Plant Road (east), Center Street (south), Rigmaiden Avenue (west), and 8th Street (north). ATSDR staff worked with residents of the community to recruit the participants.
Participation was restricted to participants who were 18 years of age or older and who had lived in the designated area for at least five years. Preference was given to older people who had been long-term residents in the neighborhood. Since this investigation focused on exposure to environmental sources of dioxins, individuals with possible occupational exposure to dioxins were excluded. There was one exception to this requirement: one participant had worked for a chemical company four years prior to the EI.
Individuals were also excluded from testing if they were pregnant, or if they had a blood clotting disorder or other medical condition that precluded them from donating a 70-ml blood sample. If there was any question about the medical eligibility of a participant, the consent of their personal physician was required.
Surface soil samples (0-3 inches) and chicken eggs were collected from private residences along VCM Plant Road. ATSDR accepted a breast milk sample from one Mossville resident for analysis.
Biological Sampling and Analyses
Participants were given an appointment to come to the Rigmaiden Community Center where the blood samples were collected. They were advised to avoid eating a fatty meal prior to donating the blood sample. A licensed phlebotomist collected a 70-ml blood sample by venipuncture from 28 participants. Blood samples were collected in 10-ml glass Vacutainer® tubes. Following collection, the blood samples were allowed to clot for 1 to 2 hours at room temperature. The samples were then stored on ice and hand-delivered to the laboratory at the National Center for Environmental Health (NCEH) in Atlanta, Georgia, for analyses.
The serum samples were analyzed for CDDs, CDFs, and co-planar PCBs by the NCEH laboratory using gas chromatography/isotope dilution-high resolution mass spectroscopy [3]. The blood serum samples were also analyzed for total lipid content, so the results could be expressed as a blood lipid concentration.
ATSDR provided glass bottles with Teflon-lined caps to women who requested breast milk analyses. The women were advised to collect at least a 25 ml sample of milk in the bottle and to store it in a freezer until an ATSDR staff person collected it. One breast milk sample was collected and was stored on ice and hand-delivered to the laboratory at the National Center for Environmental Health (NCEH) for analyses.
Environmental Sampling and Analyses
ATSDR staff collected surface soil (0-3 inches) samples from three residences on VCM Plant Road. At two of the houses, the soil sample was collected from the drip line of the house; at the third house, the soil sample was collected next to the front steps. At one house, a second soil sample was collected inside a large wire coop where the owner was raising poultry. The soil samples were placed in pre-cleaned, amber glass jars and shipped by overnight express to the laboratory for analyses.
ATSDR staff also collected two chicken eggs from a resident on VCM Plant Road who was raising poultry on his property. The eggs were broken into pre-cleaned glass jars with Teflon-lined caps. The eggs were stored on ice and shipped on ice packs by overnight express to the laboratory for analyses.
Soil samples and eggs were analyzed for CDDs and CDFs by the Midwest Research Institute (MRI) in Kansas City, Missouri. MRI also analyzed a control egg purchased from a local (Kansas City) supermarket.
Consent Form
Prior to biological and environmental testing, each participant in the investigation signed an informed consent form.
In order to assess the health impact of a mixture of dioxin-like compounds, risk assessors often convert the toxicity of individual congeners to TCDD toxicity equivalents (TEQs) using Toxicity Equivalent Factors (TEFs) [4]. The toxicity of the mixture is then assumed to be equal to the sum of the individual components. The World Health Organization recently evaluated new scientific data and recommended revised TEFs for some dioxin-like compounds [5].
In the draft report for this Exposure Investigation (May 7, 1999), blood TCDD-TEQ concentrations were calculated using the previous TEFs so that the results could be compared to reference values that were also calculated using the old TEFs. In this report, the blood TCDD-TEQ concentrations were calculated using the new TEFs, which results in higher TEQ values. The new TEF values were used so the results could be compared to updated comparison values that were calculated with the new TEF values (see Appendix 1).
The use of TEFs only affects the calculated TCDD-TEQ concentrations (the bottom line in Table 1). The concentrations of individual dioxin congeners are not affected by TEFs and remain unchanged from the draft report.
In this report, as well as in the draft report, the dioxin TEQ concentrations in soil, egg, and breast milk samples were calculated using the TEFs previously recommended by the EPA [4]. These TEFs values were used so that the TEQ levels in egg, soil, and breast milk samples could be compared to reference values in the scientific literature that were calculated using the previous TEFs.
Biological Samples
Blood
Blood serum samples from 28 adults were analyzed for dioxin-like compounds. Dioxin TEQs in the blood serum samples ranged from 3.8 to 186 parts per trillion (ppt) on a lipid-adjusted basis. The median dioxin TEQ concentration was 54.8 ppt, and the mean dioxin TEQ concentration was 68.3 ppt. Table 1 contains the median, mean, and 95th percentile concentrations of dioxin-like compounds for the EI participants and a comparison population. The derivation of background dioxin levels in the comparison population is discussed in Appendix 1.
Table 1 - Concentrations of dioxin-like compounds (pg/g lipid or ppt) in blood serum
samples from EI participants
| Analyte | Residents- median |
Comparison Population - median |
Residents - mean |
Comparison Population - mean |
Residents - 95th percentile |
Comparison Population - 95th percentile |
| 2378D | 7.3 | 2.0 | 7.6 | 2.3 | 18.2 | 4.8 |
| 12378D | 19.2 | 4.8 | 28.8 | 5.1 | 77.1 | 9.1 |
| 1234/678D | 99.1 | 61.0 | 131.8 | 58.2 | 306 | 106 |
| 123789D | 13.6 | 6.3 | 17.8 | 6.4 | 37.1 | 11.9 |
| 1234678D | 102.7 | 65.2 | 126.9 | 71.3 | 351.3 | 143.8 |
| 1234679D | 4.25 | 3.0 | 4.2 | 3.2 | 13.1 | 9.2 |
| OCDD | 906 | 556 | 1126 | 626 | 2429 | 1288 |
| 2378F | 0.0 | 0.9 | 0.2 | 0.7 | 1.2 | 1.8 |
| 12378F | 0.0 | 0.8 | 0.2 | 0.7 | 1.6 | 1.8 |
| 23478F | 8.1 | 5.6 | 11.9 | 5.9 | 38.0 | 11.5 |
| 1234/678F | 16.8 | 10.5 | 22.3 | 10.7 | 76.7 | 19.9 |
| 123789F | 0.0 | 0.8 | 1.2 | 0.6 | 4.9 | 2.0 |
| 234678F | 1.7 | 2.3 | 3.1 | 2.0 | 15.4 | 4.1 |
| 1234678F | 19.6 | 11.3 | 25.2 | 12.2 | 67.2 | 24.5 |
| 1234789F | 0.0 | 1.4 | 0.4 | 1.1 | 2.3 | 3.0 |
| OCDF | NR | 11.0 | NR | 7.7 | NR | 70.2 |
| 3344-PCB | ND | 38.9 | ND | 34.7 | ND | 100.7 |
| 3445-PCB | 0.0 | 3.2 | 1.2 | 3.2 | 8.2 | 7.4 |
| 33445-PCB | 31.7 | 16.9 | 59.7 | 20.5 | 172 | 55.7 |
| 334455-PCB | 27.0 | 20.2 | 39.9 | 20.5 | 105.7 | 39.4 |
| TCDD-TEQs(1) | 54.8 | 19.9 | 68.3 | 21.0 | 162.3 | 37.5 |
NR - not reported due to analytical interference
ND - not detected
(1) calculated using TEFs recommended by the World Health Organization [5]
Breast Milk
A human breast milk sample contained 13.5 ppt of dioxin TEQs on a lipid-adjusted basis.
Environmental Samples
Soil
Surface soil samples were collected from three residential yards located across the street from a VCM plant. The concentrations of dioxin TEQs in the three samples were 0.004, 0.019, and 0.028 parts per billion (ppb). At one house, a surface soil sample from the front yard contained 0.019 ppb dioxin TEQs, and a surface soil sample from the owner's chicken coop contained 0.0006 ppb dioxin TEQs.
Eggs
Two chicken eggs given to ATSDR by a Mossville resident and a control egg from a Kansas City supermarket were analyzed for dioxin-like compounds. The results were reported as picograms dioxin TEQs per gram of wet weight and picograms dioxin TEQs per gram of egg lipid.
Table 2 - Dioxin TEQ concentrations in chicken eggs
| Kansas City egg | 0.101 pg/g (wet weight) | 0.946 pg/g (egg lipid) |
| Mossville egg # 1 | 0.200 | 2.09 |
| Mossville egg # 2 | 0.235 | 1.76 |
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