NTP by the Numbers
The National Toxicology Program produces prodigious amounts of data in the pursuit of toxicological truth, but what do all those numbers mean? The NIEHS News (p. A354) describes the work of the institute's statisticians, who ensure that NTP rodent studies are evaluated in a comprehensive, consistent, and objective manner.
Paradise Regained?
Restoring an ecosystem to its original pristine state is an enormously complex challenge and may even be impossible for some sites. This month's Focus (p. A356) examines some of the problems inherent to ecological restoration and studies case examples from across the United States.
A Breach of Protocol
The Kyoto Protocol, developed in 1997 as an international means of reducing greenhouse gas emissions, has only 24 signatories to date, none of them major emissions producers. The Spheres of Influence (p. A362) explores the story behind some nations' reluctance to sign, as well as the growing conviction by many scientists that such a step is desperately needed.
Parts Is New Parts
Although commercially raised chickens and turkeys are mostly used up through processing as food, poultry waste products including mountains of feathers can still add up. The Innovations (p. A366) describes new technologies that turn waste feathers into valuable fiber products such as diapers, insulation, and clothing, giving the poultry industry something new to crow about.
Safety of Iodine for Water Disinfection
Iodine is sometimes used as a water disinfectant when public sources of potable water are unsafe or in disaster and medical relief situations. Risk is involved because excess ingestion of iodine can cause thyroid disorders. A Commentary by Backer and Hollowell (p. 679), who reviewed human trials on iodine safety, indicates that there is marked individual sensitivity, necessitating a risk-benefit decision for iodine. The authors report that with proper techniques and monitoring for thyroid function, iodine can be used for water treatment for prolonged periods.
Health Effects of Intensive Swine Production
Cole et al. (p. 685) reviewed the occupational and community health effects of concentrated swine feeding operations because of the enormous waste production involved, the effects of waste on air quality, and the potential transfer of pathogenic agents. Currently the level of available knowledge is inadequate to make specific recommendations, but the information should provide a foundation for future investigations into the problems.
Genistein and Breast Cancer
A review by Bouker and Hilakivi-Clarke (p. 701) examined the relationship between diet and newly diagnosed breast cancers with respect to the higher risk of cancer for Caucasians compared to Asians. The authors focus on the soy component, specifically genistein, in the Asian diet as a possible component that may or may not be responsible for the differences in cancer risk. (Also see Science Selections, p. A370)
Thermal Cleanup of PAH-Contaminated Soil
Richter et al. (p. 709) examined nonoxidative thermal decontamination as a technology to clean up contaminated Superfund sites. The authors show that thermal treatment of polycyclic aromatic hydrocarbon-contaminated soils may generate toxic by-products, including cyclopenta[cd]pyrene and benzo[a]pyrene, that require further cleanup by oxidation or other measures.
Genetic Effects on Blood Lead and Cadmium
Blood levels of lead and cadmium were evaluated in twins by Björkman et al. (p. 719) to determine the influence of genetic factors on these biomarkers of environmental exposure. The authors report that blood lead and cadmium concentrations in women were influenced by hereditary factors, possibly related to metal uptake and storage.
Comparisons of in Vitro Estrogenicity Assays
Fang et al. (p. 723) compared three assays for estrogen activity to determine their quantitative agreement in identifying structurally diverse estrogens. The estrogen receptor binding assay effectively predicted results from yeast assays and the MCF-7 cell proliferation assay when antiestrogens were excluded. Antiestrogens were identified as outliers in these estrogen activity screens. The data suggested that a combination of the three assays supplied biologic information that was not apparent from individual assays.
Arsenic, Cadmium, and Lead in Water
Ryan et al. (p. 731) obtained drinking water samples and consumption levels from individuals for analysis of arsenic, cadmium, and lead. Arsenic and lead concentrations were within the ranges reported for the United States, whereas cadmium was only detectable in 8% of the samples. Variance in exposure and drinking water consumption was evident between individuals; the authors discuss these implications for future research.
Magnetic Fields and Heart Rate Variability
Heart rate variability is predictive of long-term cardiac morbidity and mortality. Graham et al. (p. 737) examined humans exposed to 60-Hz magnetic fields and found no effects, except when hourly blood samples collected from an indwelling catheter were also used. In these cases, alterations in heart rate variability occurred, suggesting that changes are coupled to brain activity and that deleterious effects may occur when accompanied by increases in physiologic arousal, stress, or sleep disturbance.
Internal Radiation and Cancer Mortality
In a retrospective study, Ritz et al. (p. 743) evaluated cancer mortality in workers at a nuclear research and development facility. Between 1950 and 1994, 441 of 2,297 workers died from cancer of the blood and digestive tract, suggesting that occupational exposure to internal radiation could be causally related. The authors indicate that further studies in other facilities are needed to provide confirmation of the data. (Also see Science Selections, p. A370)
MTBE Exposure and Neurosensitivity
Fiedler et al. (p. 753) conducted double-blind, repeated 15-min exposures of 12 methyl tertiary butyl ether (MTBE)-sensitive individuals to air, gasoline, gasoline with 11% MTBE, or gasoline with 15% MTBE. Physiologic and psychologic responses were evaluated before, during, and immediately after exposure; although there were effects of self-reported sensitivities to gasoline with 15% MTBE, there was no dose response or symptom specificity to MTBE, as reported in epidemiologic studies. (Also see Science Selections, p. A371)
Chlorinated Water and Birth Weight
Yang et al. (p. 765) evaluated 18,029 women whose first child was born between 1994 and 1996 to examine the potential relationship between use of chlorinated water and the incidence of low birth weight in Taiwan. The data suggest that there is no association between drinking chlorinated water and the risk of low birth weight, although inherent methodologic limitations in this study limited accurate means of exposure assessment.
The Herbicide Roundup Inhibits Steroidogenesis
Walsh et al. (p. 769) screened eight contemporary-use pesticide formulations for their ability to inhibit steroidogenesis. The authors report that one pesticide, Roundup, inhibited steroidogenesis by disrupting activity of steroidogenic acute regulatory protein, and that this further demonstrated the susceptibility of this biosynthetic step to environmental pollutants.
Air Pollution and Daily Mortality
Between 1987 and 1995 Moolgavkar (p. 777) analyzed the time-series of daily total nonaccidental and cause-specific deaths in California, Illinois, and Arizona metropolitan areas. Air was monitored for PM10, carbon monoxide, sulfur dioxide, and nitrogen dioxide, as well as PM2.5 in California. Air pollution was strongly associated with total nonaccidental and cardiovascular disease mortality; in general, carbon monoxide, but not ozone, was much more strongly associated with mortality than was particulate matter.
Chemical Alteration of Child Development
A scientific meeting sponsored by the Learning Disabilities Association and government agencies (p. 785) concluded that research funding was warranted for work on the potential cause-and-effect relationship between exposure to endocrine-disrupting chemicals and alterations in child learning and behavior. Human and animal studies have suggested that exposure of the fetus to lead, methylmercury, polychlorinated biphenyls, dioxins, and pesticides alters development of the brain and could lead to subsequent learning disabilities including attention deficit hyperactivity disorder.
Liver Angiosarcoma after Occupational Exposure to Vinyl Chloride
Hozo et al. (p. 793) report on two plastic industry workers who developed angiosarcoma or hemangiopericytoma of the liver after occupational exposure to vinyl chloride. The authors recommend continuous medical surveillance, which allows patients to be diagnosed and treated earlier and to receive better prognoses.
Last Updated: August 23, 2000
