Concentrations and frequency distribution of chlorinated hydrocarbons in the residential wells near the R factory
| Downstream area (to the north of the Route No. 1 and the factory) | Upstream area | ||||||
|---|---|---|---|---|---|---|---|
| Well water concentration (n=44) | Estimated lifetime average daily intake† for carcinogens (mg/kg/day) | Well water concentration (n=2) | |||||
| Chemicals | Carcinogenicity IARC group | Median (range) (μg/l) | Percentage above MCL* | Reasonable maximal exposure | Average exposure | Median (range) (μg/l) | Percentage above MCL |
| NA, not available in International Agency of Research on Cancer (IARC) or US EPA; ND, not detected. | |||||||
| *Maximum contaminant level (MCL) is the national drinking water standard set by US EPA.7 | |||||||
| †Lifetime average daily intake was defined as the exposure dose per unit body weight and per day, averaged over 70 years from inhalation and dermal absorption based on residents’ exposure scenarios.13 | |||||||
| Vinyl chloride | 1 | 0.003 (ND–72.3) | 29.5% | 4.22E–04 | 3.64E-07 | ND | 0 |
| Tetrachloroethylene | 2A | 2.95 (ND–5228.3) | 45.5% | 4.45E–02 | 2.89E-05 | 0.05 (ND–0.1) | 0 |
| Trichloroethylene | 2A | 28.43 (ND–1790.7) | 65.9% | 1.96E–02 | 1.62E-04 | 0.1 (0.1–0.1) | 0 |
| 1,1-dichloroethylene | 3 | 1.35 (ND–1240.4) | 27.3% | ND | 0 | ||
| 1,1,1-trichloroethane | 3 | 0.67 (ND–1504.4) | 11.4% | ND | 0 | ||
| cis-1,2-dichloroethylene | NA | 3.05 (ND–1376.0) | 15.9% | ND | 0 | ||
| 1,1-dichloroethane | NA | 1.81 (ND–227.9) | NA | 0.05 (ND–0.1) | NA | ||