Photolytic Method for Destruction of Dioxins in Liquid Laboratory Waste and Identification of the Photoproducts from 2,3,7,8-TCDD

Abstract

Analytical and other research laboratories that generate small volumes of dioxin-containing wastes have no convenient method for their disposal. We have used ultraviolet photolysis with a low-pressure mercury lamp to destroy dioxin-like compounds, both as individual congeners and in actual waste analytical samples, down to nondetect levels. Photolysis promises to be an efficient, safe, and inexpensive method for on-site treatment of liquid laboratory wastes that are contaminated by dioxin-like compounds, allowing the treated materials to be discarded as regular organic solvent waste. Experiments with 1,6-[3H]-2,3,7,8-TCDD revealed that the principal photolytic pathway involves cleavage of C−O bonds rather than C−Cl bonds, giving chlorinated hydroxydiphenyl ethers as the initial products and accounting for the low material balances of reductive dechlorination products previously found upon photolysis of PCDDs. The photolysis products from 2,3,7,8-TCDD do not bind to either the Ah receptor or the estrogen receptor in vitro, making it unlikely that the products from UV treatment of PCDD/PCDF in laboratory waste will show either Ah or estrogen receptor-mediated toxicological effects.