Development of a system to test for the toxicity of solar irradiated polynuclear aromatic hydrocarbons and preliminary data using mammalian cell cultures

Graduation date: 1983Polynuclear aromatic hydrocarbons (PNAH) classified as noncarcinogens\ud may be photooxidized to mutagenic or toxic products by\ud near-ultraviolet (NUV) wavelengths of sunlight (290-320 nm). The\ud possibility that this represents a major degredation pathway in the\ud aquatic environment is of increasing concern. Large quantities of\ud PNAH from accidental oil spills, anthropogenic and natural combustion,\ud surface run-offs, and industrial discharges are being\ud released into the aquatic ecosystem. In addition there is growing\ud evidence that the stratospheric ozone layer may be diminishing.\ud As a result, more NUV wavelengths from sunlight will reach the\ud earth's surface.\ud The purpose of this study was to design a system that can\ud measure the effects of simulated sunlight ( 290 nm) irradiated\ud PNAH on mammalian cells. A second observation was to utilize\ud the system developed, to collect preliminary data on the effects\ud of two PNAH parent compounds, fluoranthene and phenanthrene, on\ud mammalian cells.\ud The first set of experiments, conducted during development\ud of the system, involved the selection of methanol as the most\ud suitable PNAH solvent. Determination of the rate of PNAH degradation\ud was also determined during the initial experiments. Other\ud system-related experiments included an analysis of the effects of\ud (a) plastic tissue-culture dishes, (b) methanol, (c) phosphate\ud buffered saline (PBS), and (d) 5-bromodeoxyuridine (BrdUrd) on\ud the induction of sister chromatid exchanges (SCEs) and/or cell\ud survivals of Chinese hamster ovary (CHO) cells. The experimental\ud results indicated that none of these factors significantly affected\ud either the survival or the number of induced SCEs in the CHO cells.\ud Preliminary data indicated that in the absence of simulated\ud sunlight, PNAH compounds did not cause an increase in SCEs, nor a\ud decrease in cell survival. However, CHO cells exposed to supersaturated\ud concentrations of fluoranthene and a simulated sunlight\ud ( 290 nm) light dose of 2000 or 3000 j-sec/m² did not survive.\ud At similar light doses and lower fluoranthene concentrations, the\ud induction of SCEs and mutation frequency were increased.\ud The data from phenanthrene studies indicated there was a\ud decrease in survival in cells exposed to super-saturated concentrations\ud and a simulated sunlight ( 290 nm) dose of 6000 j-sec/m²\ud The number of SCEs was not increased in cells exposed to lower\ud phenanthrene concentrations and light doses of 2000 or 3000\ud j-sec/m²