for dioxin in soils to 72 ppt for residential soil and 950 ppt for commercial/industrial soil. The EPA considered lowering those numbers even further to 3.7 ppt TEQ in residential soil and 17 ppt ...

and dioxin-like polychlorinated biphenyls of 0.025 pg/Nm3 I - Teq (picograms per normal cubic meter in terms of total equivalent toxicity), lower than the reference values currently used by the ...