Childhood Asthma
A public-private partnership named Open Airways for Schools is a preventive program in urban elementary schools designed to reduce exposures to airborne pollutants that trigger asthma. In the Commentary, O'Neill reports that asthma has a disproportionate impact on children and minorities (particularly blacks) and warrants increased efforts to reverse this trend. Community-based education is discussed as one of the first steps necessary in the process.
The Facts on Phytoestrogens
Phytoestrogens, chemicals found in plants such as soybeans, whole grains, dates, and pomegranates, have been used for thousands of years for medicinal purposes. Scientists have discovered that these chemicals may function as estrogen agonists or antagonists when eaten by humans and may produce both beneficial and adverse health effects. The Focus article discusses this emerging field of research.
NIOSH Develops NORA
1996 marks the 25th anniversary of the establishment of the National Institute for Occupational Science and Health. Achievements of the institute's history include the virtual eradication of diseases such as black lung and brown lung and the sharp decline in workplace injuries. Not content to rest on these laurels, NIOSH Director Linda Rosenstock has brought together a coalition of government, industry, labor, and health-care leaders to develop the National Occupational Research Agenda--outlined in the Spheres of Influence --a set of priorities to guide NIOSH's next 25 years.
Now Dry-cleaning Is All Wet
New dry-cleaning methods, discussed in the Innovations article, use either liquid carbon dioxide or special soap- and-water techniques to clean clothes without using the potentially carcinogenic chemical perchloroethylene.
Children and Acid Aerosols
A comprehensive study of the adverse health effects of air pollution in North American children was conducted by investigators from The Harvard School of Public Health and the Environmental Health Directorate, Ottawa, Canada. Studies on exposure by Spengler et al., respiratory symptoms by Dockery et al., and pulmonary function by Raizenne et al. identified the highest acidic aerosol concentrations in the area west of the Appalachian mountains and west of the Allegheny range up through southern Ontario. The primary source of particulate acidity, mass, sulfate, and ozone was correlated with coal-burning regions with a high sulfur dioxide source and their downwind transport regions. The site selections for epidemiologic studies represented an eightfold range of exposures. Between 1988 and 1991, questionnaires gathering data for about 13,000 young children indicated that fine particulate sulfate was associated with increased reports of bronchitis but not with asthma or other respiratory symptoms. Standardized pulmonary function tests on the children suggested that long-term exposure to ambient particle acidity may have a deleterious effect on normal lung growth, development, and function.
Drinking Water Contaminants
Two articles in this issue focus on drinking water. In the first study, Kanitz et al. gathered data on body weight, body length, and cranial circumference from hospital records of 676 births in Genoa, Italy, to determine potential associations with maternal use of drinking water disinfected with chlorine dioxide and/or sodium hypochlorite. The authors report a higher frequency of short body length and smaller cranial circumference in offspring of mothers that drank water treated with chlorine compounds. In addition, the presence of neonatal jaundice was almost twice as likely when the water had been treated with chlorine dioxide. Age and smoking habits did not influence the outcome of the study.
In the second study, van Maanen et al. examined the potential health risks of drinking well water in the Netherlands that was contaminated with high levels of nitrate. Concentrations of nitrate ranged between 0.02 and 17.5 mg/l in public water supplies and between 25 and 135 mg/l in well water. The authors report that ingestion of well water with high nitrate levels may be associated with genotoxic risk as indicated by increased mutation frequencies in peripheral lymphocytes and by endogenous formation of carcinogenic N-nitrosocompounds from nitrate-derived nitrites.
Children and PAHs
van Wijnen et al. used the biomarker 1-hydroxypyrene (1-HP) to evaluate polycyclic aromatic hydrocarbon (PAH) exposure in 1- to 6-year old children in areas containing five different levels of PAHs in the Netherlands. Values of 1-HP ranged between 1.58 nmol/l in the reference area to 2.71 nmol/l in a polluted area. The predictive value of single measurements of the biomarker was low. There was no consistent association between urinary 1-HP and soil PAH content in neighborhoods built on coal mine tailings, although indoor sources of PAH were weakly correlated with the biomarker.
Regional P450 Activity in Liver
Heinonen et al. characterized activities and inducibility of cytochrome P450 metabolizing enzymes to investigate individual and species differences in susceptibility to toxicants. Precision-cut rat liver slices and confocal laser cytometry were used in combination with fluorescence analysis to determine regional P450 enzyme activity in slice perfusion chambers. Induction of P450 isozyme-specific substrates enabled analysis of regional-specific induction of P450 enzyme activities that could not be determined by conventional methods. These novel techniques permit examination of futher correlations between P450 mRNA, isozyme protein content, or other factors and enzyme activity on an individual cell basis.
Estrogen Screen for Natural and Xenoestrogens
Arnold et al. developed a yeast estrogen screen to measure estrogenic activity by increases in ß-galactosidase enyzme activity. Assay specificity was confirmed by reactivity with natural and xenoestrogens and by lack of response to nonestrogens. The data suggested that estrogenicity of compounds depends on a combination of factors: binding affinity for the estrogen receptor, bioavailability, bioaccumulation, and rate of biodegradation.
PCB and TCDD Synergism
van Birgelen et al. measured porphyrin accumulation in liver of rats fed combinations of TCDD and several different PCBs to investigate potential synergism between the chemicals. One of the PCB congeners, PCB 153, interacted with TCDD to increase hepatic porphyrin levels 800-fold higher than in controls, suggesting that the mechanism of synergistic activity involved induction of cytochrome P450 isoenzyme activity and activation of other enzymes in the porphyrin metabolic pathway.
Last Update: June 9, 1997