Carcinogens and mutagens in the undergraduate laboratory

Abstract

Carcinogens are a serious, unrecognized health hazard in many chemistry laboratory courses.The latent period between human exposure to a carcinogen and the onset of cancer may be 20 years or more. Thus carcinogens are often not handled as carefully as chemicals with immediate damaging effects. According to one current estimate, 90% of cancers result from exposure to environmental factors, including exposure to chemicals, cigarette smoke, air-borne particulate matter such as asbestos, as well as dietary and alcohol intake (2). Three epidemiological studies (in the United States, Sweden, and Britain) have indicated that chemists, par ticularly those working in laboratories, have an unusually high death rate from cancer (2)(3)(4). This tragedy may be due in part to the fact that many veteran chemists handle potentially dangerous materials with the "contempt bred by familiarity." However, although those who work with carcinogens for long periods undergo the greatest risk, a brief exposure may be sufficient to induce cancer. 2V-nitrosodithylamine and N-nitroso-di-rcbutyiamine have been shown to cause cancer in test animals following a single dose (5). Occupational exposures to benzene as brief as two years have been associated with leukemia (6). Hence, all students and instructors participating in chemistry courses need to be aware of the hazards of handling carcinogens.Concern at San Francisco State University over such health hazards motivated our investigation. The project was a cooperative effort of faculty and students in the Departments of Chemistry and Biology. It involved two stages: to identify carcinogens and suspected carcinogens used in the labs, and to make recommendations for their elimination or control. These recommendations are based on toxicological properties, volatility, how the chemicals were used in the labs, and in what quantities, and on our assessment of how serious a hazard was posed by a chemical in light of the available evidence.

Mutagenicity evaluation of nitroanilines and nitroaminophenols in Salmonella typhimurium

“…In contrast to these results, o-nitroaniline was found to be nonmutagenic in other studies in several strains of Salmonella typhimurium. including TA1538 (2)(3)(4)(5). Negative results for o-nitroaniline are also reported for Escherichia coli strains WP2 and WP2uvrA-and in a test for UDS in rat hepatocytes (4).…”

“…The same compound was found to induce chromosome aberrations in Chinese hamster lung fibroblasts in vitro (16) but did not cause an increase in the frequency of dead implants in the dominant lethal test in rats (15). In Salmonella typhimurium, 2-nitro-4aminophenol have been reported to be mutagenic (17) or weakly mutagenic (l), but a purified sample of the chemical was found to be non-mutagenic (18); it was also negative in a UDS test (19) and a dominant lethal test (1,5). Both 4-nitro-3-aminophenol and 3-nitro-4-aminophenol were non-mutagenic in Salmonella typhimurium (10) with and without metabolic activation.…”

Microscale organic laboratory: I: An approach to improving air quality in instructional laboratories

“…of 0.3 would seem to add a reasonable element of conservatism to eqn. (2) for our laboratory for the purposes of these estimates. Some results are summarized in Table 2.…”

Laboratory air quality. Part I. A concentration model

“…A = 1 + (tv/kft0) [exp(-fet0Av) -exp(-fo0(l -f)/tv)\ (4) where t0 is the length of the laboratory period; {is the fraction of the laboratory period over which emissions occur (f=ti/to); tv is the characteristic ventilation time for the well-mixed room (tv = V7Q); and n is the number of students in the laboratory section. The further assumption has been made that, for a given receptor, k is identical for all sources or, alternatively, that k represents an average for all sources.…”