Environews
Toxicogenomics at MIT
Researchers continue to explore the possibilities for fighting environment-related disease at the gene level. This month's NIEHS News (p. A234) highlights the work being conducted at the Massachusetts Institute of Technology Toxicogenomics Research Center. Researchers there are focusing on DNA repair functions and ways to battle fungal toxins that can cause liver cancer, as well as collaborating with researchers at other institutions to standardize gene expression profiling data for a much-anticipated centralized data system.
Crush of Cars
In developing countries, private automobile ownership is increasing rapidly. This shift from less costly and simpler modes of transportation to a system composed of individual automobile drivers has created unique environmental problems, especially for heavily populated cities in these countries. The Focus (p. A238) discusses the challenges facing citizens in these transitioning societies, and examines some ways that governments and private organizations are responding.
Environmental Externalities
The invention of the automobile has irrevocably changed our way of life. Although there are undeniable benefits associated with the phenomenon of individual car ownership, there are certain side effects that must be acknowledged as well. The Spheres of Influence (p. A246) examines some of the costs and consequences of our dependence on personal automobiles, and describes current and proposed strategies to address these issues so that we can all drive into the future with cleaner air.
Grasping the Concept
In this era of rising gas prices, how close are we to mass-producing personal transportation vehicles that end our dependence on hydrocarbon fuels? Proponents of alternative fuels are moving us closer every day. The Innovations (p. A250) discusses one possibility--the midsize Hypercar® concept, powered by a hybridized hydrogen fuel cell, which is geared to compete with today's SUVs. In a world in love with the midsize family car, could this be the alternative vehicle we've been waiting for?
Research
Environmental Concern: Racial-Ethnic Differences
Greenberg (p. 369) surveyed New Jersey residents and found that non-Hispanics and English-speaking Hispanics were more concerned about environmental problems than were Asians and Spanish-speaking Hispanics. There were also racial/ethnic differences in the desire for action and in support of the environmental movement. Asians and Spanish-speaking Hispanics are the fastest growing subpopulations in the United States. Acculturation may slowly increase their concern about environmental pollution, and it is important to better understand their environmental perceptions.
Air Pollution and Pregnancy Outcome
Many studies have investigated the effects of ambient air pollution on birth outcomes. Srám et al. (p. 375) found evidence implicating air pollution in adverse effects, but the strength of the evidence differs between birth outcomes. There is a relationship between air pollution, postneonatal respiratory death, and birth weight, but the evidence is insufficient for causality between air pollution, preterm birth, and intrauterine growth retardation. For birth defects, the evidence so far is insufficient to draw conclusions.
Toxicology and Chemical Mixtures
The assessment of chemical mixtures is a complex topic for toxicologists, regulators, and the public. Monosson (p. 383) explores the link between the science of toxicology and the needs of government agencies. Historically, chemical regulation and toxicologic research have emphasized individual chemicals. The current practice of mixture assessment relies primarily on the existing single chemical database. However, chemical mixture science and assessment is moving forward through combined efforts of regulatory agencies and scientists from a broad range of disciplines including toxicology.
Levels of Bisphenol A and 4-Nonyl Phenol in Human Urine
Bisphenol A (BPA) is used to manufacture polycarbonate plastic, and 4-nonyl phenol (NP) is used to make widely used nonionic surfactants. Calafat et al. (p. 391) measured BPA and NP in archived urine samples from a reference adult population in the United States. BPA was detected in 95% of the samples at ≥ 0.1 µg/L of urine. NP was detected in 51% of the samples ≥ 0.1 µg/L. The study provides the first reference range of human internal dose levels of BPA and NP in a demographically diverse human population.
Perchlorate and Fathead Minnow Thyroid Function
Perchlorate is an environmental contaminant that acts as a competitive inhibitor of thyroidal iodide uptake in mammals, but the impacts of perchlorate in aquatic ecosystems are unclear. Crane et al. (p. 396) investigated the effects of exposures to concentrations of ammonium perchlorate occurring in the environment (1, 10, and 100 mg/L) on development of fathead minnows (Pimephales promelas) for 28 days postfertilization. Results indicate that environmental levels of ammonium perchlorate affect thyroid function; in the early life stages, these effects may be associated with developmental retardation.
The Precautionary Principle and Risk Perception
Possible adverse health effects due to electromagnetic fields (EMF) present a major public health issue across Europe. Because scientists cannot exclude that EMF may cause health problems, the application of the precautionary principle is being debated heavily. Wiedemann and Schützet al. (p. 402) present results from two studies indicating that precautionary measures may trigger concerns and amplify perceptions of EMF-related risk. Such impacts, questioning common expectations, should be considered in decisions about precautionary measures. (Also see Science Selections, p. A255)
World Trade Center Respiratory Health Effects
Reibman et al. (p. 406) investigated whether previously normal residents in the community surrounding the World Trade Center (WTC) would have an increased incidence of persistent respiratory symptoms and abnormalities. Questionnaire and screening spirometry data were used to compare residents of "exposed" and "control" areas. No differences in spirometry between the groups were detected. However, the survey data demonstrated an increased rate of new onset and persistent respiratory health effects in exposed residents compared with the control population.
ETS Exposure and Urinary Hormone Markers
Chen et al. (p. 412) explored whether environmental tobacco smoke (ETS) affects reproductive hormone profiles as characterized by urinary pregnanediol-3-glucuronide (PdG) and estrone conjugate (E1C) levels among married nonsmoking women who intended to conceive. ETS exposure was associated with significantly lower urinary E1C levels among nonconception cycles, suggesting that the adverse reproductive effect of ETS may act in part through its antiestrogenic effects. (Also see Science Selections, p. A254)
Chlorination By-products and Pancreatic Cancer
Chlorination disinfection by-products (CDBPs) are produced during the treatment of water with chlorine and are associated with an increased risk of bladder cancer. Do et al. (p. 418) report results from a population-based study of pancreatic cancer cases and age- and sex-matched controls. Exposure to chlorination by-products was estimated by linking lifetime residential histories to CDPB levels in water supplies. Regression analysis showed no evidence of increased pancreatic cancer risk at higher CDBP concentrations. Null findings were also obtained assuming a latency period for pancreatic cancer induction of 3, 8, or 13 years.
Interactions between Phthalates and PCBs
Humans are exposed to phthalates and polychlorinated byphenyls (PCBs), and PCBs may inhibit enzymes responsible for phthalate metabolism. Hauser et al. (p. 425) explored the interaction between phthalates and PCBs in relation to human semen quality among men in subfertile couples. For low sperm motility there was a greater than additive interaction between monobenzyl phthalate and PCB-153. There was also a greater than additive interaction between monobutyl phthalate (MBP) and PCB-153 and a suggested interaction between MBP and the sum of PCBs.
Xenoestrogens Induce Calcium Influx and Prolactin Secretion
Xenoestrogens (XEs) interfere with endogenous estrogens such as estradiol (E2) to disrupt normal estrogenic signaling. Wozniak et al. (p. 431) investigated the effects of E2 versus several XEs on a pituitary tumor cell line with high membrane estrogen receptor-
. Each XE produced a unique temporal pattern of Ca2+ elevation. E2 and each XE also caused unique time- and concentration-dependent patterns of prolactin (PRL) secretion. At very low concentrations, XEs mediate membrane-initiated intracellular Ca2+ increases resulting in PRL secretion via a mechanism similar to that for E2, but with distinct patterns and potencies.
Cardiac Repolarization and Air Pollution
Particulate air pollution is associated with cardiovascular morbidity and mortality. Henneberger et al. (p. 440) tested the hypothesis that patients with preexisting coronary heart disease experience changes in repolarization in association with air pollution. Electrocardiogram results indicate an increase in QT duration in response to exposure to organic carbon; a decrease in T-wave amplitude with ultrafine, accumulation mode and PM2.5 (< 2.5 µg in diameter) particles; and a corresponding increase of T-wave complexity. The study provides evidence for an immediate effect of air pollution on key factors in cardiac death. (Also see Science Selections, p. A254)
Alkyl Phenols and Diethyl Hexyl Phthalate in Sheep Tissue
Rhind et al. (p. 447) studied alkyl phenols and phthalates in selected tissues from ewes and their lambs grazing pastures fertilized with either sewage sludge (treated) or inorganic fertilizer (control). Phthalates were detected in tissues of control and treated animals in relatively high concentrations. Sludge was not associated with consistently increased tissue concentrations of either alkyl phenols or phthalates. Results suggest that sewage sludge in pastures is unlikely to cause large increases in tissue concentrations in sheep and other similar animals.
The Effect of Ultrafine Carbon Black on VEGF in Lungs
Ultrafine carbon black (ufCB) can cause proinflammatory response and increase alveolar-capillary permeability. Chang et al. (p. 454) explore the role of vascular endothelial growth factor (VEGF), a vascular permeability factor, in ufCB-induced alveolar-capillary permeability by intratracheal instillation of ufCB in mice. Results indicate that ufCB induces the production of VEGF. The induction of VEGF by ufCB acts through a reactive oxygen species-dependent pathway.
Domoic Acid Transfer to Milk
Domoic acid (DA) is a neurotoxin produced by the diatom genus Pseudo-nitzschia. DA can contaminate filter-feeding organisms and be transferred by ingestion to higher trophic levels. Intoxication in humans and marine mammals has been attributed to DA, but it has not been demonstrated whether DA can be transferred from DA-exposed mothers to nursing young. Maucher and Ramsdell (p. 461) demonstrate the transfer of DA from spiked milk to the plasma of nursing neonatal rats, and a longer DA retention in milk versus plasma after 8 hr in exposed dams.
Remediation of DNAPL Source Zones: A Review and Assessment
The infiltration of dense nonaqueous phase liquids (DNAPLs) into the saturated subsurface typically produces a highly contaminated zone that serves as a long-term source of dissolved-phase groundwater contamination. Christ et al. (p. 465) review laboratory and field evidence that supports the development of a treatment strategy that combines aggressive source-zone removal with promotion of sustained microbial reductive dechlorination.
Environmental Medicine
Impact of Occupational Exposure on Lead Levels in Women
Popovic et al. (p. 478) examined the effects of occupational exposure and lifestyle on bone and blood lead levels. Former smelter employees and referents provided samples and answered a questionnaire on lifestyle and medical history. In the exposed group, lead concentrations in tibia and blood were significantly higher and the age at the onset of menopause was lower. Blood lead levels remained increased in women long after the cessation of exposure. Exposed women had lower bone lead concentrations than most male workers. Current models of exposure extrapolated from male data may be inappropriate for women.
Respiratory Morbidity in Office Workers
Cox-Ganser et al. (p. 485) conducted a questionnaire study on building-related respiratory disease and associated social impact in a water-damaged office building. Compared with the U.S. adult population, prevalence ratios were 2.2-2.5 for wheezing, lifetime asthma, and current asthma; 3.3 for adult-onset asthma; and 3.4 for symptoms that improved away from work. Respiratory problems accounted for one-third of sick leave, and respiratory cases with work-related symptoms used more sick days. The morbidity and lost work-time burdened both employees and employers.
Lead Shot in the GI Tract
Gustavsson and Gerhardsson (p. 491) present the case of a woman with an increased blood lead concentration (550 µg/L) of unknown origin suffering from malaise, fatigue, and gastrointestinal (GI) symptoms. No source of lead exposure could be identified, but she had consumed game occasionally. An abdominal X ray revealed a 6-mm round metal object in the colon ascendens. Before the object could be localized, it was spontaneously released from the colon. The patient's blood lead levels slowly declined and her symptoms disappeared. The authors recommend abdominal X ray in investigations of blood lead elevations of unknown origin.
Children's Health
Birth Outcomes and in Utero Exposures to Organophosphorus Insecticides
Three prospective cohort studies recently evaluated the relation between exposure (as assessed by biomonitoring) of pregnant women to organophosphorus pesticides and several birth outcomes. Needham (p. 494) compare the studies in terms of the exposure scenarios and exposure assessments. The primary focus is on the exposure assessments, all of which employ biomonitoring but use different approaches, which may contribute different relations between exposure and birth outcomes.
Effects of Indoor- and Outdoor-Generated Particles
People spend the majority of their time indoors exposed to a combination of indoor-generated particles and ambient particles that have infiltrated. Koenig et al. (p. 499) combined a predictive model for estimating infiltration efficiency to separate personal exposure to PM2.5 (particulate matter < 2.5 µg in aerodynamic diameter) into its indoor- (Eig) and ambient-generated (Eag) components for children with asthma. Eig and Eag were compared to changes in exhaled nitric oxide (eNO), a marker of airway inflammation. The ambient-generated component of PM2.5 is consistently associated with increases in eNO, and the indoor-generated component is less strongly associated with eNO.
Variation in Urinary OP Metabolites
Children of farm workers are at increased risk of exposure to organophosphate (OP) pesticides. Lambert et al. (p. 504) quantified dialkyl phosphate levels in serial urine samples from children, 2-6 years of age, in three Oregon communities hosting differing agricultural industries. The median level of dimethyldithiophosphate, a common metabolite, was higher in urine samples from children in the three agricultural communities relative to a reference group. Temporal variation within the children also demonstrates the need for multiple urine samples to accurately characterize longer-term and/or cumulative exposures.
Age-Related Differences in Carcinogenesis
Hattis et al. (p. 509) discuss implications for assessing human risks for full lifetime exposures, considering uncertainties in projections from the rodent data. The combined effects of uncertainties were estimated with Monte Carlo analyses. Among the uncertainties analyzed, the mapping of rodent life stages to human ages/exposure periods is most important quantitatively. The estimated population mean risk from lifetime exposures at constant milligrams per kilogram body weight to a generic mutagenic carcinogen is 2.8-fold larger than expected from adult-only exposure.
