Selecting Proper Doses
A Commentary by Foran, who summarized conclusions reached by an ILSI Risk Science Institute working group, suggests that implementation of recommended dose selection principles that do not rely solely on maximal tolerated dose will improve the quality and consistency of the rodent bioassay on an international basis.
Is Sewage Recycling Safe?
Treatment of 182 million gallons of sewage per person per day results in 7 million metric dry tons of biosolids, and creates an enormous disposal problem. Although controversial due to public perceptions about human by-products, recycling of biosolids for agricultural uses is being strongly encouraged by the EPA. The Focus article explores the debate about the safety of using recycled biosolids.
The Truth about Toxic Releases
As mandated toxics release reporting enters its 10th year, various representatives of government, industry, and public interest groups assess the success and future of the Toxics Release Inventory in the Focus article. While the TRI is seen by some as overreaching and underutilized, it is hailed by others as an environmental and public access to information victory.
The End of Polluter Pays?
In May 1996 Judge W. Brevard Hand set the environmental law community on its ear when he threw out a toxic waste liability action on the basis that the Superfund act could not be applied retroactively. The Spheres of Influence article examines the impact of the ruling which goes against 15 years of precedent among courts for holding "responsible parties" liable for cleanup costs regardless of when they did the polluting.
Stress Gene Sleuths
A new technique for tracking toxicants, described in the Innovations article, uses stress genes from bacteria in assays to predict cellular damage to mammalian cells caused by environmental injury.
Cancer Incidence Near Three Mile Island
Wing et al. reanalyzed data from the 1979 nuclear accident at TMI. The original report indicated that there was no increase in cancer incidence in surrounding areas. However, when adjustments for age, sex, socioeconomic characteristics, and pre-accident variation in incidence were considered, associations between radiation exposure and incidence rates of leukemia, lung cancer, and all cancer were increased above original estimates. Results support the hypothesis that radiation doses are related to increased cancer incidence around TMI.
Ozone in Southern California
A comparison between ozone exposure measured by personal monitors and stationary oudoor monitors highlights a very high degree of exposure misclassification in epidemiological settings (Liu et al.). The low predictive power of ozone measurements was due primarily to spatial variation in outdoor ozone, equipment errors, and time-activity records.
Blood Lead in Children Covered by Medicaid
A demographic study of risk factors for elevated lead in about 90,000 Texas children showed that 10-14% of children aged 19-48 months exhibited blood lead levels greater than 10 
g/dl (Kurtin et al.). Three risk factors found for excessive blood lead in children were ethnicity, gender, and age, with the subgroup of 2-4 year old African American males showing the greatest percentage incidence of elevated lead (17.3%).
Predicting Bioactivity of Xenoestrogens
A serum based assay to measure relative binding affinity of xenoestrogens to estrogen receptors in MCF-7 human breast cancer cells was developed by Nagel et al. Assay of two xenoestrogens, bisphenol A and octylphenol, predicted that the estrogenic bioactivity of the former was over 500-fold greater than the latter. Exposure of pregnant mice to as low as 2 ppb bisphenol A caused increased prostate weight, demonstrating that environmentally relevant doses of this xenoestrogen are capable of altering fetal development.
Hexachlorobenze Metabolism in Humans
To-Figueras et al. measured HCB metabolites in serum and urine of 100 highly exposed subjectes and reported HCB in all serum samples (1.1-953 ng/ml). The major urinary metabolites included pentachlorophenol and pentachlorobenzenethiol; the latter cysteine conjugate was quantitatively more important and served as a good urinary marker of HCB internal dose and glutathione-mediated metabolism.
Relationship between Climate and Mortality
Kalkstein and Greene evaluated climate/mortality relationships using a new air mass-based synoptic procedure to estimate how predicted global warming would alter these values. Models that estimate climate change for years 2020 and 2050 estimate that summer mortality will increase dramatically and winter mortality decrease slightly, resulting in a net increase in weather-related mortality by as much as 30-50 deaths if climate warms as models predict.
Magnetic Fields and Tumor Co-promotion
McLean et al. report that 60-Hz magnetic fields did not enhance the activity of the skin tumor promoter phorbol-12 myristate-13 acetate in three independent experiments in 288 mice, although the assay may not have been sensitive enough to detect the activity of weaker tumor co-promoters.
Exposure to DDT in Mexico
DDT metabolites in fat tissue from 40 sprayers and questionnaires from another 331 employees were used by Rivero-Rodriguez et al. to construct a model to assess chronic occupational exposure to DDT pesticide exposure. The metabolite DDE was selected as the indicator of chronic exposure; a linear model indicated predicted values of 9.56-298.4 g/g fat for the pesticide, suggesting a need for exposure prevention programs and more secure application measures and hygiene.
Reproductive Toxicity of Di-n-butylphthalate
Wine et al. examined the reproductive toxicity of the phthalate ester di-n-butylphthalate (DBP) in rats using the continuous breeding protocol test in rats. Adverse reproductive and developmental effects of DBP were noted in the second generation of rats that were greater than effects found in the first generation, including indices of mating, pregnancy and fertility, and degenerative seminiferous tubules and defective epididymides.
Last Update: March 7, 1997
