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Herring-gull (Larus argentatus) eggs were collected from five locations on the Great Lakes and from one colony on the Atlantic coast for organochlorine analysis and mutagenesis testing. The Great Lakes colonies were chosen for their different contaminant levels, while the Atlantic coast colony was used as a relatively clean control. The eggs were homogenized and extracted, and the extracts were tested in the Salmonella/mammalian microsome assay for induction of point mutations and in Chinese hamster ovary (CHO) cells for the Induction of sister chromatid exchanges (SCEs) and chromosome aberrations. None of the extracts was mutagenic in Salmonella, either in the presence or absence of metabolic activation. However, all of the extracts, including the clean control, caused significant increases in both the SCE rate and in the number of chromosome aberrations in the CHO cells. There was no apparent relationship between contaminant levels and the magnitude of these responses or the doses at which they occurred, although the chemical analysis indicated a wide range in the concentrations of the different organochlorides present.

Naturally incubating herring gulls (Larus argentatus) were exposed to No. 2 fuel oil. The gulls were treated either early (seven to ten days after clutch completion) or late (when the second egg of the clutch reached the pip stage) in incubation. Hatching success of eggs of adults oiled early in incubation was reduced at 321 ml oil/m2 and survival of young to seven days post-hatch was reduced at both 107 and 321 ml/m2. This decrease in survival at 107 ml/m2 suggests that a concentration of oil which is not lethal to the embryos may have a sublethal effect which reduces chick viability. When adults were oiled late in incubation, the only effect noted was decreased hatching success at 321 ml/m2. Chicks between five and nine days of age which were exposed to an artificial slick of 321 ml No. 2 fuel oil/m2 exhibited decreased survival to seven days post-treatment. Since 107 ml/m2 is more than 20 times the maximum thickness of No. 2 fuel oil slicks which have been measured on the Great Lakes, a single exposure of an adult at the incubation stages tested or of a young chick to a free-floating oil slick would probably not cause a significant reduction in hatching success or survival of young. The effects of repeated exposure to a fresh fuel oil slick are unknown.

Toluenesulfonhydrazide (TSH) is a high volume production chemical for which there is relatively little toxicological data. In this study, the mutagenic activity of TSH was determined in the Salmonella/mammalian microsome assay and the in vitro chromosomal aberration assay using Chinese hamster ovary cells. TSH induced gene mutations both with and without metabolic activation in the Salmonella/mammalian microsome assay but that it did not induce chromosomal aberrations in Chinese hamster ovary cells. The results of this study indicate that TSH is an in vitro mutagen and should be assessed for in vivo mutagenicity.

Competing Interests: The authors declare no competing financial interest.