Science Tutors
This month's NIEHS News (p. A258) describes the palette of programs offered by the NIEHS to bring environmental health science to K-12 students and their teachers, including mentorships, customized curricula, and multimedia instructional materials developed especially for different grade levels.
No Way to Behave
The Focus (p. A262) looks at the incidence of neurobehavioral problems such as autism, ADHD, aggression, and learning disabilities in children, and examines the potential links between these disorders and early exposure to environmental contaminants.
Little Data on Little Kids
The Spheres of Influence (p. A268) explores the issue of regulating children's exposure to chemical and pharmaceutical agents. Children are traditionally exempt from clinical research and safety trials because of their inability to give informed consent, only to find themselves sometimes inadequately protected by regulations designed to meet adults' needs.
Children's Health Assessment
Armstrong et al. (p. 469) developed a methodology to determine which chemicals are most likely to present risks of exposure for children. This methodology included a screening step, a hazard assessment, and a margin-of-exposure calculation. The tiered approach for chemical selection and their effects on children's health could ensure that research is focused on the highest priority chemicals.
Children's Exposure Assessment
Cohen Hubal et al. (p. 475) reviewed factors that influence exposure of children to environmental contaminants and the data for characterization and assessment of exposure with a focus on children's activity patterns. Because current data are insufficient to assess environmental contaminant exposure, several general areas of research are suggested to correct the deficiencies.
Endocrine Disruptors and Human Health
Safe (p. 487) reviewed studies which hypothesize that synthetic estrogenic chemicals may be responsible for endocrine disruption. He reports that many of the male and female reproductive tract problems linked to endocrine disruption have not increased and are not correlated with synthetic industrial contaminants.
X Rays and Risk of Childhood Leukemia
Infante-Rivard et al. (p. 495) evaluated approximately 500 children who had received diagnostic X rays and found that the subsequent risk of childhood acute lymphoblastic leukemia rose from 1.10 with one exposure to 1.60 after the second irradiation. Among girls, the odds ratio rose from 1.14 for one exposure to 2.26 for two exposures, but the responses changed if a gene repair variant was present in the child, suggesting a gene-environment interaction. (Also see Science Selections, p. A273)
No Cancer in Children of Sawmill Workers
The potential for offspring of sawmill workers to develop cancer from chlorophenate exposure was evaluated by Heacock et al. (p. 499) in 19,674 children. There were 40 cases of cancer in approximately 260,000 person-years of follow-up, providing little evidence to support a relationship between the risk of childhood cancer and paternal occupational exposure to chlorophenate fungicides in British Columbian sawmills.
Model of Chlorpyrifos Exposure in Children
Zartarian et al. (p. 505) modeled children's residential exposure to chlorpyrifos using a time-dependent microactivity approach. The authors report that the use of human activity data combined with analytical data can provide information about pesticide exposure and dose from different media, routes, and pathways.
Pesticide Risks for Farm Children
Fenske et al. (p. 515) analyzed urinary organophosphate metabolites in approximately 100 children 0-6 years of age from an agricultural community in Washington. Pesticide doses were estimated from urinary metabolites based on toxicokinetic models which assumed that azinphos-methyl or phosmet were the most frequently used pesticides. Many of the children exhibited contaminant exposures that exceeded chronic reference doses or acceptable daily intake values for the pesticides. (Also see Science Selections, p. A272)
Alkylphosphates in Pesticide-Exposed Children
Aprea et al. (p. 521) monitored approximately 200 Italian children 6-7 years of age for urinary excretion of six organophosphorus pesticide metabolites. Metabolite concentrations in children were higher than those in adults, and were associated with the proximity of vegetable gardens and ornamental plants to dwellings, and to cut flowers and pets in houses.
Fetal Development after Lead Exposure
Han et al. (p. 527) used a rodent model to evaluate the effects of calcium supplements given during pregnancy to prevent transfer of accumulated lead from mother to fetus. The authors observed reductions in fetal lead accumulation in rats fed diets with normal calcium content, suggesting that calcium intake is beneficial during pregnancy. (Also see Science Selections,
p. A273)
Biomarker for Ozone-Damaged Lungs
Broeckaert et al. (p. 533) developed a sensitive, noninvasive biomarker for ozone damage to lungs in humans and confirmed this biomarker in mouse studies. Exposure to photochemical smog containing ozone at concentrations as low as 0.060 ppm induced an early leakage of lung Clara cell protein, indicating that there was little safety margin for lung toxicity by ozone.
Hexachloronaphthalene Hastens Spermatogenesis
Hexachlorinated naphthalene accelerated the rate of spermatogenesis in male offspring of rats treated during pregnancy. Omura et al. (p. 539) found that the onset of secretion of pituitary hormones (luteinizing hormone and follicle-stimulating hormone) were also accelerated, suggesting this endocrine disruption was the cause of early-onset spermatogenesis. Concentrations of chemical in rats were similar to those found in human adipose tissue, indicating that similar endocrine disruption might occur in exposed humans.
Mortality from the Three Mile Island Accident
Talbott et al. (p. 545) conducted a morbidity and mortality evaluation of over 32,000 Pennsylvania residents who lived near Three Mile Island at the time of the nuclear accident. The study followed members from 1979 to 1992; although there were increases in relative risks for some cancers, there was no consistent evidence that radioactivity significantly impacted cancer-related mortality. The authors recommend follow-up studies because of the prolonged latency period for the development of cancers.
Chemical versus Bioassay Analysis for Dioxin
Pauwels et al (p. 553) compared analyses of dioxin-like compounds in human samples using either gas chromatography (GC) or chemical-activated luciferase gene expression (CALUX). The CALUX assay measures the total toxic equivalence of dioxin-like mixtures, whereas GC measures the sum of four major PCB congeners. There was good correlation between methods, suggesting that the inexpensive CALUX method could be used as a prescreening tool in epidemiologic surveys.
Genotoxic Effects of Endosulfan
Lu et al. (p. 559) used an in vitro technique to examine the genotoxic effects of the isomers of the pesticide endosulfan. Sister chromatid exchanges, micronuclei, and single-cell gel electrophoresis assays suggested that both *-endosulfan and ß-endosulfan are genotoxic to Hep G2 cells, with ß-endosulfan being the stronger toxicant.
Particle Association with Daily Mortality
Schwartz (p. 563) reports that high concentrations of airborne particles in 10 U.S. cities are associated with daily deaths and that increased mortalities are not influenced by seasons, other airborne pollutants, or socioeconomic conditions between cities.
Exposure to Mercury from the Chloralkali Industry
Symanski et al. (p. 569) report that health risks associated with occupational or environmental contaminants are critically affected by intra- and interindividual sources of variation in exposure measurements. The evaluation of workers at a Swedish chloralkali plant showed that creatinine-corrected urinary mercury better characterized worker exposure than airborne or blood mercury concentrations.
DMSA Treatment of Pediatric Metallic Mercury Exposure
To prevent development of neurotoxicity in nine children who were exposed to metallic mercury vapors, Forman et al. (p. 575) initiated treatment with oral meso-2,3-dimercaptosuccinic acid (DMSA). The authors report that oral chelation with DMSA produced a significant mercury diuresis, with no observed adverse side effects.
Last Updated: June 8, 2000
