Table 2

Hazard rankings of selected persistent organic pollutants

Acute hazard rating*Cancer rating†US EPA RfD and ATSDR MRL (mg/kg/day)§
Chemical(s)WHOUS EPAIARCUS EPAEndocrine disruptor status‡US EPAATSDR
*Acute ratings from the World Health Organisation (WHO) are based on oral, dermal, or inhalation LD50 values: Ia, extremely hazardous; Ib, highly hazardous; II, moderately hazardous; III, slightly hazardous. Acute ratings from the US Environmental Protection Agency are based on US National Toxicology Program oral rat LD50 data:24 I, LD50 <50 mg/kg; II, LD50 = 50–500; III, LD50 = 500–5000; IV, LD50 >5000. †International Agency for Research on Cancer (IARC) rating system.25 US EPA ratings from their Integrated Risk Information System (IRIS) database.26 ‡“Yes” means there is published evidence of endocrine disruption in animals or humans for this chemical.27 §Reference doses (RfDs) are from the US EPA IRIS database.26 Minimal risk levels (MRLs) (oral, chronic or intermediate) from the Agency for Toxic Substances Disease Registry (ATSDR).28 ¶Most toxic isomer of this group of compounds.
**RfDs given for two PCB mixtures: Aroclor 1060 and Aroclor 1254. US EPA has not come to a consensus value for the RfD for Aroclor 1248 because the lowest dose tested caused an infant death in a species of monkey that was tested. RfD for Aroclor 1260 was not available. Agency for Toxic Substances Disease Registry Minimal Risk Level (MRL) is only available for Aroclor 1254.
AldrinIbIB2, ProbableYes3×10−53×10−5
ChlordaneIIII2B, PossibleB2, ProbableYes5×10−46×10−4
DDT, DDEIIII2B, PossibleB2, ProbableYes5×10−45×10−4
DieldrinNAII3, UnclassifiableB2, ProbableYes5×10−55×10−5
2,3,7,8-Tetrachloro-dibenzo-p-dioxin¶NAI1, KnownA, KnownYesNA1×10−9
2,3,4,7,8-Penta-chlorodibenzofuran¶NAI1, KnownA, KnownYesNA3×10−8
EndrinIbI3, UnclassifiableD, UnlikelyYes3×10−43×10−4
HeptachlorIIII2B, PossibleB2, ProbableYes5×10−4NA
HexachlorobenzeneIaIV2B, PossibleB2, ProbableYes8×10−42×10−5
MirexNAII2B, PossibleNAYes2×10−48×10−4
PCBs**NANA2A, ProbableB2, ProbableYes7×10−5 (1060), 2×10−5 (1254)2×10−5 (1254)
ToxapheneNAII2B, PossibleB2, ProbableYesNA1×10−3