In situ assessment of genotoxic hazards of environmental pollution.

The potential impact of the environmental pollutants on human health can be evaluated by the laboratory analysis of the environmental samples or by the measurement of the biological effects on indigenous populations and/or specific test organisms placed in the environment to be monitored. A canary in a cage, used by 19th century miners as a biological indicator for rising levels of toxic gases, is a classical example of in situ hazard identification. The induced toxic effects are often the result of synergistic and antagonistic interactions among various physical and chemical factors that are difficult to reproduce in the laboratory. Therefore, conceivably the biological effects measured on or near the impacted site have greater relevancy for hazard assessment to man than from the data derived from the environmental samples analyzed in the lab. The organisms most commonly employed for the assessment of mutagenicity under real-world conditions are: (1) flowering plants, (2) wild and captive mammals, and (3) aquatic vertebrates. Plant species such as Tradescantia paludosa, Zea mays, and Osmunda regalis have been used for monitoring ambient air quality around several major industrial cities in the U.S.A., nuclear power plants, and industrial waste sites, and also for the assessment of potential health effects of municipal sewage sludges. Domestic animals such as dogs can be used as sentinels to provide information on the effects of contaminants in the environment and have been used to a limited extent to evaluate the environmental influences on the occurrence of breast cancer and osteosarcoma. Cytogenetic analysis from feral and wild animals has been employed for assessing the health hazards and prioritizing the clean-up efforts at hazardous waste sites. Aquatic animals have been used more often than terrestrial animals or plants to identify and characterize the genotoxic effects of environmental pollution. Since 1970, a number of studies has been reported on the mutagenic and neoplastic effects on aquatic animals from coastal areas and continental rivers, lakes, and ponds. The limitations of in situ environmental assessment are lack of control over the physical environmental components, inherent variability and interactions of test organisms, lack of control of exposure doses, and difficulty of finding concurrent experimental controls. Nevertheless, flowering plants, terrestrial, and aquatic animals may serve as useful sentinels and biomarkers of environmental pollution.

Effects of chemical smokes on flora and fauna under field and laboratory exposures.

Various types of obscurant smokes are used routinely in training by the U.S. Army. Because continued routine use of the smokes could be detrimental to the native flora and fauna at training sites, a preliminary biological and chemical field study of fogoil, hexachloroethane, and tank diesel smokes was conducted. Smoke plumes were sampled and chemically analyzed at distances of 15-150 m from the smoke source where Tradescantia clones 4430 and 03 and the native plant Ambrosia dumosa and the native rodent Dipodomys merriami were exposed for 30 min. In addition, Tradescantia clone 4430 was exposed to tank diesel in the laboratory at concentration levels equivalent to exposure at 15 and 50 m. Tradescantia clones were examined for mutagenic effects indicated by micronuclei induction in developing pollen and pink somatic mutations in stamen hairs. Photosynthetic perturbations were measured in Tradescantia and A. dumosa using variable fluorescence induction. Animals were examined for sister chromatid exchanges and chromosome aberrations. It was found that all of the smokes tested exerted varying degrees of physiological and mutagenic effects in one or more assay system at one or more exposure distance. The studies reported here indicate that exposed ecological systems, or at least components of these systems, are at a higher risk than are unexposed components (e.g., organisms) for several types of damage attributed to obscurant smoke exposure.

Mutagenicity in the vicinity of a lead smelter.

The mutagenicity of the environment in the vicinity of a lead smelter was examined for 3 years by studies of changes in the frequencies of male germinal mutations of the waxy-C system of Zea mays and somatic mutations of the stamen hair system of Tradescantia. A transect was run at 0.3, 1.7, 3.2, 7.4, and 11.4 km predominantly downwind from the smelter. The mutagenic responses vary between years, within a year, and with distance. Mutation frequencies are both directional and nondirectional with distance. Concentrations of Pb, Cd, Cu, and Zn measured in soil samples show directional changes with distance each of the 3 years, and joint monotonicity is observed in some cases between mutation frequency with distance and metal concentrations with distance. Of a total of ten experiments with both Zea mays and Tradescantia, eight show significantly higher mutation frequencies at one or more locations close to the smelter than at locations more distant or at other controls.

Mutagenicity of the environments in the vicinity of an oil refinery and a petrochemical complex.

The mutagenicity of the vicinity of an oil-refining complex and a petrochemical complex was examined using the germinal revertant frequency of Zea mays waxy-C W22 and the somatic stamen hair system of Tradescantia. A 3-year study was conducted at Wood River, Illinois, in 1978, 1979, and 1980, and a 1-year study in 1979 at Beaumont, Texas. The studies conducted in 1978 registered the effects of airborne pollutants and possible soil pollutants. The studies in 1979 and 1980 registered only the effects of airborne pollutants. Elevated mutation frequencies of Zea mays compared to various controls occurred in 1978, 1979, and 1980 at both complexes. The mutation frequencies of Zea mays were particularly high, up to 26-times control values. By contrast, the mutation frequencies of Tradescantia were much lower, with maximum mutation frequencies five times control value.

Statistical analysis of urinary delta-aminolevulinic acid (ALAU) excretion in the white-footed mouse associated with lead smelting.

ALAU in white-footed mice trapped in the vicinity of a lead smelter has been measured to study the biological effect of lead smelting operations and the rate at which the ALAU level diminishes after removing animals from contaminated environments. The statistical method which has been developed for this purpose shows that the ALAU levels are initially higher among animals near the smelter and diminish to a common level after 5-6 weeks. The statistical method is generally applicable to a variety of physiological functions which exhibit a decay curve with respect to time.

Growth Inhibition of Caenorhabditis elegans and Panagrellus redivivus by Selected Mammalian and Insect Hormones.

Caenorhabditis elegans and Panagrellus redivivus were cultured in axenic medium in microwells. The addition of selected steroids and terpenoids to the medium caused quantitative inhibition of numbers of offspring produced per well. Three out of 14 vertebrate sex hormones and analogs, and seven out of 10 insect juvenile hormones and analogs inhibited growth at 25 or 50 micrograms per ml. In addition, two insecticide synergists which mimic juvenile hormones, propyl 2-propynyl phenyl phosphonate and piperonyl butoxide, inhibited growth at 7 mug/ml. Total lipids from Panagrellus and from Nematospiroides dubius were inhibitory. Separation by silicic acid column chromatography yielded active and inactive portions. We concluded that the inhibition observed was non-specific.