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 dioxinlike 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 ,6-3{sup left}H-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.
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