Table 5.
Comparison of Oral Health Reference Values for p,p’-DDD and Analogues
| Chemical | p,p’-DDD | p,p’-DDT | p,p’-DDE | Methoxychlor |
|---|---|---|---|---|
| POD for subchronic RfD/MRL (mg/kg-day) | NDa | 0.05 (NOAEL) | 5 (LOAEL) | 5 (LOAEL) |
| Critical effect | NDa | Liver lesions in rats exposed for 15–27 weeks | Increased relative liver weight in male offspring rats exposed during gestation and lactation | Precocious puberty in female rats (i.e., accelerated vaginal opening) exposed in utero, during lactation and after weaning |
| Source | (U.S. EPA, 2017b) | (ATSDR, 2002a) | (U.S. EPA, 2017c) | (ATSDR, 2002b) |
| POD for chronic RfD (mg/kg-day) | NDa | 0.05 (NOAEL) | 5 (LOAEL) | 5.01 (NOAEL) |
| Critical effect | NDa | Liver lesions in rats exposed for 15–27 weeks | Increased relative liver weight in male offspring rats exposed during gestation and lactation | Excessive litter loss in rabbits exposed during gestation (i.e., spontaneous abortion) |
| Source | (U.S. EPA, 2017b) | (U.S. EPA, 1987) | (U.S. EPA, 2017c) | (U.S. EPA, 1990) |
| Carcinogenicity classification | B2; probable human carcinogen | B2; probable human carcinogen | B2; probable human carcinogen | D; not classified as to human carcinogenicity |
| OSF (mg/kg-day)−1 | 2.4 × 10−1 | 3.4 × 10−1 | 3.4 × 10−1 | ND |
| Basis | Liver tumors in mice | Liver tumors in mice and rats | Liver tumors in mice and hamsters | Human data is unavailable and animal evidence is inconclusive |
| Source | (U.S. EPA, 1988c) | (U.S. EPA, 1988a) | (U.S. EPA, 1988d) | (U.S. EPA, 1988b) |
a
Toxicity data for p,p’-DDD is insufficient for the derivation chemical-specific oral health reference values; however, screening-level values have been developed for this chemical by U.S. EPA (2017b) based on a read-across approach.
Abbreviations: LOAEL, lowest-observed-adverse-effect level; ND, not determined; NOAEL, no-observed-adverse-effect level; MRL, minimal risk level; OSF, oral slope factor; POD, point of departure; RfD, oral reference dose.