External Review Released
After spending a year reviewing the overall direction, organization, and workings of the NIEHS, the institute's external review working group has summarized its findings in a public report. The NIEHS News (p. A376) examines the report and highlights some of the group's findings.
Rolling in Green
Some 46.5 million acres of U.S. land, including lawns, golf courses, and sports fields, are covered in plush turf. While a well-tended carpet of green may offer some environmental and economic benefits, the golf and turf industries present their share of environmental health problems. The pros and cons of keeping lawns are described in the Focus article (p. A378).
Half a Century of Health
In 1998, the World Health Organization celebrates fifty years of working to advance the state of the world's health. In honor of this anniversary, the Spheres of Influence (p. A386) takes a comprehensive look at the organization's roots, some of its achievements, and where it's headed next under the leadership of its new director-general Gro Harlem Brundtland.
Cancer of the Thyroid
Three papers review relationships between the thyroid and cancer. These consider thyroid and hormonal regulation of carcinogenesis (Hard, p. 427), the carcinogenic action of pesticides (Hurley et al., p. 437), and risk assessment for thyroid cancer (Hill et al., p. 447). Rodent studies have shown that disruptions in the thyroid-pituitary axis can result in thyroid tumors, whereas acute exposure to ionizing radiation remains the only verified cause of thyroid carcinogenesis in humans. There appears to be no antithyroid activity until critical intracellular chemical concentrations are reached, suggesting that there may be a practical threshold for thyroid cancer. Of 167 pesticides evaluated for carcinogenicity by the U.S. EPA, 24 produced thyroid follicular cell tumors in rodents. Mutagenicity does not seem to be a major determinant in thyroid carcinogenicity.
Nitrosamine Formation from Dietary Sources
Vermeer et al. (p. 459) fed human volunteers diets rich in amines in combination with nitrate at the acceptable daily intake level (ADI). An increased formation of potentially carcinogenic, volatile N-nitrosamines was observed, suggesting that both the current ADI and the drinking water guideline for nitrate should be reconsidered.
Uranium Is Tumorigenic to Human Osteoblasts
Miller et al. (p. 465) report that depleted uranium is capable of transforming human osteoblastic cells to the tumorigenic phenotype. Risk of cancer induction from internalized depleted uranium exposure may be comparable to other biologically reactive and carcinogenic heavy metals such as nickel.
Distribution and Transfer of Lead in Adults
Hernandez-Avila et al. (p. 473) sampled bone, blood, and plasma lead in humans to determine if lead mobilized from bone to plasma was adequately reflected by whole-blood lead. While there was a correlation between whole-blood lead and plasma lead, trabecular bone lead exerted an additional independent influence on plasma lead. The authors suggest that it is important to determine the degree of this influence during pregnancy and lactation, when there is heightened bone turnover of lead.
Combined Neurotoxicity of PCBs and Dioxins
Kodavanti and Ward (p. 479) investigated potential interactive effects of complex PCB mixtures in an in vitro rodent brain cell system. The authors suggest that biological effects of binary mixtures of PCB congeners fit a dose-additive model, indicating a specific site of action that is Ah-receptor independent with potential human health risks from this group of chemicals.
Neurotoxicity of Mining Waste
Rodents were fed mining wastes containing arsenic, manganese, lead, and cadmium from Villa de la Paz, Mexico, to investigate potential alterations in brain neurochemistry (Rodriguez et al., p. 487). Brain dopamine release was decreased, and when rodents were challenged with long-standing stimulation, they were unable to sustain an increased dopamine release, suggesting that neurotoxic components from the mining waste may represent a health risk for the exposed population.
Pollutant Effects on Nitrogen Metabolism
In vitro cell cultures were used by Arndt et al. (p. 493) to investigate the impact of toluene on protein metabolism. The new effect-monitoring system uses stable isotope labeling with ciliate species and may provide a powerful tool for environmental medicine.
Lead in Children from Jakarta
Heinze et al. (p. 499) measured blood lead and hematological biomarkers in 131 children from four districts in Jakarta, Indonesia. About 25% of the Indonesian children living in the urban areas had blood lead levels above acceptable limits. Activities to reduce pollution and to continue monitoring were recommended.
Exposure to Nickel from Russian Refineries
Urinary nickel levels were measured by Smith-Sivertsen et al. (p. 503) in populations residing near Russian nickel refineries and in those living in areas without point source exposure to nickel. There were 2,233 urine samples analyzed, with the people living in Nikel, Russia, exhibiting the highest nickel concentrations (4.9 µg/l, compared to 0.9 µg/l in control areas). Industrial air pollution could not explain observed differences between regions, indicating that additional nickel exposure sources require investigation.
PCBs in Breast Milk
Korrick and Altshul (p. 513) examined breast milk from 122 mother-infant pairs living in proximity to New Bedford Harbor, Massachusetts, a site contaminated with elevated levels of polychlorinated biphenyls (PCBs). Indirect exposure through the food chain was a potential source for PCB ingestion. Four newborns from mother-infant pairs were identified with excessive PCB levels. There were no apparent toxic effects associated with the contaminant, and the authors concluded that the benefits of breast-feeding outweighed any risks from transfer of low levels of PCB to the nursing infants.
Last Updated: July 24, 1998
