GENOTOXICITY STUDIES IN SEMICONDUCTOR INDUSTRY - PRIMARY DNA-DAMAGE BY WASTE SAMPLES RESULTING FROM PLASMA-ETCHING AS DETECTED BY P-32 POSTLABELING

The covalent binding of chemicals from solid wastes from the microelec tronic industry on DNA in vitro and in vivo was examined. Adduct forma tion is detected by means of the P-32-postlabeling technique using the nuclease pi enhancement procedure. No adducts could be analysed by me ans of the standard procedure with excess ATP and the adduct intensifi cation technique, respectively. Only waste chemicals taken from the pl asma reactor were found to bind to DNA. Waste chemicals originating fr om the turbo pump and the air system did not produce adducts detectabl e under these conditions. Treatment of DNA in vitro with waste chemica ls resulted in adduct patterns with a few distinct and dominant adduct spots besides a high number of minor adducts forming a radioactive zo ne on the thin-layer chromatogram In experiments on treatment of DNA w ith 0.2mg/ml waste taken from the plasma reactor, the total relative a dduct labeling index (RAL)* for all labeled adducts was found to be 1 .1 +/- 0.61 x 10(-7). One major adduct found after this treatment comp rises about 5% of the total radioactivity (RAL 4.9 x 10(-9)). A simila r adduct pattern was found in DNA taken from the skin of mice treated topically with 5 mg waste from the plasma reactor in 4 daily doses. Th e RAL for the radioactive zone was found for this dosage to be 0.40 +/ - 0.15 x 10(-7). The RAL for the major adduct was calculated with 3.9 x 10(-9). No adducts were detected in DNA taken from the liver and spl een of mice treated with the waste samples. Our results indicate the p ossibility of genotoxic effects might be due to dermal exposure with s olid waste originating in the plasma etching reactor.