DOVER CHEMICAL CORPORATION
DOVER, TUSCARAWAS COUNTY, OHIO
APPENDIX A
TABLE B-1
CONTAMINANT LEVELS IN ON-SITE SUBSURFACE SOIL (1983-86)
| CHEMICAL | RANGE (mg/kg) | DEPTH OF MAXIMUM CONTAMINANT LEVEL (Feet) |
| Carbon tetrachloride | ND-54,920 | 4-5 |
| Chloroform | ND-7,800 | 8-10 |
| Chlorobenzene | ND-110,000 | 1.5-3 |
| 1,2-dichlorobenzene | ND-1,100,000 | 1.5-3 |
| 1,3-dichlorobenzene | ND-580,000 | 9-10 |
| 1,4-dichlorobenzene | ND-2,200,000 | 9-10 |
| 1,2,4-trichlorobenzene | ND-400 | 6-8 |
ND=Chemical not detected
ppm=Parts per million
TABLE B-2
CONTAMINANT LEVELS IN ON-SITE SUBSURFACE SOIL (1989)
| CHEMICAL | RANGE (mg/kg) | DEPTH OF MAXIMUM LEVEL OF CONTAMINANT (Feet) |
| Chlorobenzene | ND-370 | 2-2.5 |
| Tetrachloroethene | ND-79 | 2-2.5 |
| Toluene | ND-18 | 3.5-4 |
| Xylenes | ND-43 | 2-2.5 |
| Benzoic acid | ND-1,000 | 7.5-8 |
| 1,2-dichlorobenzene | ND-980 | 1-1.5 |
| 1,3-dichlorobenzene | ND-660 | 1.5-2 |
| 1,4-dichlorobenzene | ND-540 | 1-1.5 |
| 1,2,4-trichlorobenzene | ND-20,000J | 1.5-2 |
| Hexachlorobenzene | ND-520 | 1-1.5 |
| Alpha-BHC | ND-38 | 4-5 |
| Dioxin (TCDD TEF) | ND-66 (µg/kg) | 1-1.5 |
ND=Chemical not detected
TCDD TEF=Polychlorinated dibenzo-dioxins measured as equivalents of 2,3,7,8
Tetrachlorodibenzo-dioxin
Calculations for Chemicals that do not cause cancer:
Noncancer Comparison Value = (U.S.EPA Reference Dose x Body Weight) / Intake Rate
Body Weight = The amount a person weights. Generally 70 kilograms is used for an adult and 10-15 kilograms for a child.
Intake Rate = The amount of water or soil a person would drink or eat.
Cancer Risk Guide
Cancer Risk Guide = (Body Weight x Risk Factor) / Intake Rate x Cancer Slope Factor
Body Weight = The amount a person weights. Generally 70 kilograms is used for an adult body weight.
Risk Factor = Either one additional cancer in one person in 10,000 people, one person in 100,000 people or one person in 1,000,000 people.
Intake Rate = The amount of water or soil a person would drink or eat.
Cancer Slope Factor = It is a U.S.EPA number which represents the cancer potential of a chemical. Each chemical has its own slope factor.
TOXICITY EQUIVALENCY FACTOR (TEF) METHOD
There are 75 different forms (isomers and homologs) of the chlorinated dioxins (TCDDs) and 135 different chlorinated furans (TCDFs). These compounds are generally divided into groups in which each group has the same number of chlorine atoms attached to the furan or dioxin ring. Each form has different chemical, physical, and toxicological properties. The 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) isomer, which is one of the dioxin isomers with four chlorine atoms, is usually thought of as the most toxic of the chlorinated dioxins. Other isomers with the 2,3,7,8 configuration are viewed as more toxic than those species that don't have this configuration. Under ideal conditions the toxicity of a mixture of chemicals is best determined by direct evaluation. However because this would be costly and time-consuming, an interim procedure for estimating the risks associated with exposure to mixtures of the chlorinated dibenzo-p-dioxins and -dibenzofurans is used. This is the Toxicity Equivalency Factor (TEF) method. The U.S.EPA classifies the toxicity of each TCDD/TCDF isomer in the mixture by assigning each form a toxicity equivalency factor with respect to the toxicity of the 2,3,7,8-TCDD isomer.
In general the method used to assess human health risks using the TEF method is performed as
follows: 1. Determine the isomeric forms in the mixture, 2. Multiply the concentrations of each
isomer by its corresponding TEF factor, 3. Sum the products of step 2 to obtain the total 2,3,7,8-TCDD equivalents in the mixture, and 4. Determine the human exposure to the mixture in
question. (The original TEF factors were modified in 1989 as shown in the table.)
