Environews
NIEHS NEWS | Moving On in Vietnam
With investment and trade agreements continuing to grow, Vietnam is a country on the verge of gaining a competitive edge in the world's manufacturing marketplace. However, along with this boost in the country's commercial base comes increased risk of occupational health problems. This article (p. A156) discusses research presented at an occupational and environmental health conference in Hanoi that examines not only the traditional health concerns of a once-poor rural nation, but also those issues that inevitably result from rapid and expanding industrialization.
FOCUS | Epigenetics: The Science of Change
The field of epigenetics has begun to garner more attention within the last few years as researchers and clinicians increasingly find connections between altered gene activity and health outcomes--possibly even the inheritance of disease across generations. This article (p. A160) describes some of the findings contributing to the growing interest in this area of study, and also discusses some of the ways research institutions and individuals are seeking to integrate it into the realm of human health research.
SPHERES OF INFLUENCE | Open House: The Ethics of Studying Children at Home
In a perfect world, communities could engage with scientists in a mutually beneficial relationship: scientists could freely gather and analyze data to provide a voice to health problems faced by community members, with all children--the most vulnerable members of our society--enjoying greater protection through the knowledge gained. But what happens when these ideals are not met or, worse, even considered? This article (p. A168) looks at a new National Academies report that recommends procedural and policy changes to ensure all ethical factors are considered and addressed in studying children at home.
INNOVATIONS | Cell Scenario: A New Look at Microarrays
Having an accurate measurement of cellular processes in microorganisms can help environmental scientists monitor and control fungal and bacterial populations to prevent loss of plant life and outbreaks of contagious human illnesses. One of the cutting-edge tools for taking these preventive measures is the Phenotype MicroArray produced by Biolog of Hayward, California. This article (p. A172) tells how the Phenotype MicroArray allows researchers to assess 2,000 cellular phenotypes simultaneously, yielding important data on the effects toxicants have on life forms.
Commentary
GENE POLYMORPHISM | Implications of Genetic Information under the Clean Air Act
The U.S. Clean Air Act (CAA) explicitly guarantees the protection of sensitive human subpopulations from adverse health effects associated with air pollution exposure. Identified subpopulations, such as asthmatics, may carry multiple genetic susceptibilities to disease onset and progression and thus qualify for special protection under the CAA. In an effort to encourage the incorporation of genomic information in regulations, the U.S. Environmental Protection Agency has issued its Interim Policy on Genomics. Kramer et al. (p. 313) make recommendations on how to integrate results from the Human Genome Project for the improvement of regulatory health science and the prerequisites for inclusion of genetic information in decision making.
Review
RISK ASSESSMENT | Nitrate in Drinking Water and Reproductive Health
In this review Manassaram et al.(p. 320) present an update on maternal exposure to nitrates in drinking water in relation to possible adverse reproductive and developmental effects, and also discuss nitrates in drinking water in the United States. Animal studies have found adverse reproductive effects resulting from higher doses of nitrate or nitrite. Some reports have suggested an association between exposure to nitrates in drinking water and spontaneous abortion, intrauterine growth restriction, and various birth defects. The authors conclude that the current literature does not provide sufficient evidence of a causal relationship between exposure to nitrates in drinking water and adverse reproductive effects.
Research
TOXICOLOGY | Surface Area Response to Ultrafine Carbon Particles
Increased levels of particulate air pollution are associated with increased respiratory and cardiovascular mortality and morbidity. Some epidemiologic and toxicologic research suggests that ultrafine particles (UFPs) are more harmful per unit mass than larger particles. Stoeger et al. (p. 328) compared the acute adverse effects of different types of carbonaceous UFPs at dose ranges that cause a moderate inflammatory response in lungs of mice. Relating the inflammatory effects to the particle characteristics (organic content, primary particle size, or specific surface area) demonstrates the most obvious dose response for particle surface area. The study suggests that the surface area measurement is a valuable reference unit for the assessment of causative health effects.
RISK CHARACTERIZATION | Diet, Betel Nut, and Arsenic-Related Skin Lesions
An established exposure-response relationship exists between water arsenic levels and skin lesions. Results of previous studies and laboratory animal studies suggest that diet may modify arsenic metabolism and toxicity. McCarty et al.(p. 334) evaluated the effect of diet on the risk of arsenic-related skin lesions in Pabna, Bangladesh. Betel nut use and increased bean intake appear to be associated with increased risk of developing skin lesions. Increased intake of fruit and canned goods may be associated with reduced risk. The study does not provide clear support for a protective effect of vegetable and overall protein consumption against the development of skin lesions, but a modest benefit cannot be excluded.
TOXICOLOGY | Correlation of Cytokines with PM Composition
Veranth et al. (p. 341) treated human lung epithelial cells (BEAS-2B) with 10-80 µg/cm2 dust, enriched with particulate matter < 2.5 µm aerodynamic diameter (PM2.5), derived from soils and road surfaces in the western United States. Each dust sample is a complex mixture containing particles from different minerals mixed with biogenic and anthropogenic materials. The observed correlations between low-volatility organic components of soil- and road-derived dusts and the cytokine release by BEAS-2B cells are relevant for investigation of mechanisms linking specific air pollution particle types with the initiating events leading to airway inflammation in sensitive populations.
HUMAN TOXICOLOGY | Lead, Cadmium, and Oxidative Stress
Oxidative stress has been proposed as a mechanism of lead and cadmium toxicity based on in vitro and animal studies, but it is uncertain whether this mechanism is relevant in the general population where there is low environmental exposure. Lee et al. (p. 350) examined associations of blood lead and urinary cadmium levels with oxidative stress markers of serum -glutamyltransferase (GGT), vitamin C, carotenoids, and vitamin E among adult participants in the Third National Health and Nutrition Examination Survey. The strong association of lead and cadmium levels with oxidative stress markers suggests that oxidative stress should be considered in the pathogenesis of lead- and cadmium-related diseases among people with low environmental exposure.
POPULATION HEALTH | Prevalence of Arsenic and Awareness of Health Risks
Parvez et al. (p. 355) conducted a population-based prevalence survey in rural Araihazar, Bangladesh, to describe the distribution of arsenic exposure in the population and to assess awareness of this problem and possible remediation options. For each well, the owner/caretaker was interviewed regarding his or her awareness of the health consequences of As exposure. More than half (54%) regularly consumed well water with an As concentration above the acceptable government standard in Bangladesh. Willingness to reduce exposure was positively related to awareness of the health risks. Increasing knowledge of the health consequences of As may be an important element in facilitating remediation.
REPRODUCTIVE HEALTH | Exposure to Ozone Alters Semen Quality
Idiopathic male infertility may be due to exposure to environmental toxicants that alter spermatogenesis or sperm function. Sokol et al. (p. 360) studied the relationship between air pollutant levels and semen quality over a 2-year period in Los Angeles, California, by analyzing repeated semen samples from sperm donors. Semen analysis data were correlated with air pollutant levels (ozone, nitrogen dioxide, carbon monoxide, and particulate matter) between 1996 and 1998. There was a significant negative correlation between ozone levels before donation and average sperm concentration. No other pollutant measures were significantly associated with sperm quality outcomes. Exposure to ambient ozone levels adversely affects semen quality.
Also see Science Selections, p. A177
RISK ASSESSMENT | West Nile Virus and Mosquito Insecticide Risks
West Nile virus (WNV) has been a major public health concern in North America since 1999. As a result, insecticides have been introduced in areas where they traditionally have not been used, and public concerns have been raised about risks from insecticide use. Peterson et al. (p. 366) used reasonable worst-case risk assessment methodology to evaluate human health risks for WNV and insecticides used to control adult mosquitoes. Results indicate that human health risks from residential exposure to mosquito insecticides are low and not likely to exceed levels of concern. Further, the risks from WNV exceed the risks from exposure to mosquito insecticides.
POPULATION HEALTH | Assessing Household Solid Fuel Use
The World Health Organization (WHO) is responsible for reporting the Millennium Development Goal (MDG) indicator "percentage of population using solid fuels." Rehfuess et al. (p. 373) present the results of a comprehensive assessment of solid fuel use and discuss the implications of their findings in the context of achieving the MDGs. Solid fuel use data were compiled from recent national censuses or household surveys for 93 countries. Reliance on traditional household energy practices has distinct implications for most of the MDGs. Development agendas need to recognize the fundamental role that household energy plays in improving child and maternal health and in fostering economic and social development.
Also see Science Selections, p. A178
CARCINOGENESIS | Aspartame Carcinogenicity
Aspartame (APM) is a widely used artificial sweetener. The results of a long-term bioassay by Soffritti et al. (p. 379) show that APM causes an increased incidence of malignant-tumor-bearing animals with a positive significant trend in males and in females, an increase in lymphomas and leukemias, a statistically significant increased incidence of transitional cell carcinomas of the renal pelvis and ureter and their precursors (dysplasias) in females, and an increased incidence of malignant schwannomas of peripheral nerves in males. The results of this mega-experiment indicate that APM is a multipotential carcinogenic agent at doses much lower than the current acceptable daily intake.
Also see Science Selections, p. A176
ENVIRONMENTAL JUSTICE | Segregation, Air Toxics, and Cancer Risk
Morello-Frosch and Jesdale (p. 386) examined links between racial residential segregation, estimated ambient air toxics exposures. and associated cancer risks using modeled concentration estimates from the U.S. Environmental Protection Agency's National Air Toxics Assessment for 309 metropolitan areas in the United States. The information was combined with measures of socioeconomic status from the 1990 Census. Estimated cancer risks associated with ambient air toxics were highest in tracts located in metropolitan areas that were highly segregated. Disparities between racial/ethnic groups were also wider in more segregated metropolitan areas.
Also see Science Selections, p. A176
GENE EXPRESSION | Profiles Mediated by Arsenite and Methylated Metabolites
The generation of toxic trivalent methylated metabolites complicates the study of arsenic-mediated carcinogenesis. Su et al.(p. 394) evaluated the effect of chronic treatment with sodium arsenite (iAsIII), monomethylarsonous acid, and dimethylarsinous acid on immortalized human uroepithelial cells using cDNA microarray. Of the genes affected by all three arsenicals, only one (coding for interleukin-1 receptor, type II) showed enhanced expression, a finding confirmed by the reduced increase in NF-B activity seen in response to interleukin-1β in iAsIII-exposed cells. The data demonstrate that chronic exposure to arsenicals has different epigenetic effects on urothelial cells and represses NF-B activity.
TOXICOGENOMCS | Gene Expression in Arsenic Carcinogenesis
Exposure to inorganic arsenic in utero produces hepatocellular carcinoma (HCC) in male mice by adulthood. To explore the molecular mechanisms of transplacental arsenic hepatocarcinogenesis, Liu et al. (p. 404) conducted a transplacental As carcinogenesis study using genome-wide microarray to profile As-induced aberrant gene expression. HCC incidence in adult males was increased 4-fold and tumor multiplicity 3-fold. Arsenic exposure in utero resulted in alterations in the expression of 2,010 genes in As-exposed liver samples and 2,540 genes in As-induced HCC. Findings are in agreement with the biology and histology of As-induced HCC, indicating that multiple genetic events are associated with transplacental As hepatocarcinogenesis.
CARDIOVASCULAR DISEASE | Systemic Microvascular Effects of Particulate Exposure
The epidemiologic association between pulmonary exposure to ambient particulate matter (PM) and cardiovascular dysfunction is well known, but the systemic mechanisms that drive this effect remain unclear. Nurkiewicz et al. (p. 412) studied the effects of pulmonary PM exposure on systemic microvascular function in rats and identified local inflammatory events. The results indicate that after PM exposure, the impairment of endothelium-dependent dilation in the systemic microcirculation coincides with polymorphonuclear leukocyte adhesion, myeloperoxidase deposition, and local oxidative stress. These microvascular observations are consistent with events that contribute to the disruption of peripheral resistance control and/or cardiac dysfunction associated with PM exposure.
TOXICOGENOMICS | Validation of Toxicogenomics-Based Test Systems
Corvi et al. (p. 420) summarize the workshop "Validation of Toxicogenomics-Based Test Systems," held December 2003 in Ispra, Italy. The aim of the workshop was to discuss and define principles applicable to the validation of toxicogenomics platforms and specific toxicologic test methods that incorporate toxicogenomics technologies. Different aspects of toxicogenomics-based test methods were covered. The three focus areas included biologic validation of toxicogenomics-based test methods for regulatory decision making, technical and bioinformatics aspects related to validation, and validation issues as they relate to regulatory acceptance and use of toxicogenomics-based test methods.
EXPOSURE ASSESSMENT | Genotyping Cryptosporidium
A workshop titled "Application of Genotyping Methods to Assess Pathogen Risks from Cryptosporidium in Drinking Water Catchments" was held at the International Water Association biennial conference, Marrakech, Morocco, 23 September 2004. Ferguson et al. (p. 430) present and discuss findings of an interlaboratory trial that compared methods for genotyping Cryptosporidium oocysts isolated from feces. The primary goal of the trial was to assess the utility of current Cryptosporidium genotyping methods for determining the public health significance of oocysts isolated from feces in potable-water-supply watersheds. A research agenda for protozoan geneticists was proposed to improve the utility of methods into the future.
REPRODUCTIVE HEALTH | A National Occupational Reproductive Research Agenda
The initial goal of occupational reproductive health research is to effectively study toxicants, physical agents, and biomechanical and psychosocial stressors that constitute reproductive hazards in the workplace. Although the primary objective is prevention, research has expanded to include a broader spectrum of chronic health outcomes potentially affected by reproductive toxicants. Lawson et al. (p. 435) describe new tools for screening reproductive toxicants and for analyzing modes of action. They recommend considering outcomes such as menopause and latent adverse effects, as well as including exposures such as shift work and nanomaterials.
BUILT ENVIRONMENT | Indoor Chemistry and Health
Chemicals present in indoor air can react with one another, either in the gas phase or on surfaces, altering the concentrations of both reactants and products. Such chemistry is often the major source of free radicals and other short-lived reactive species in indoor environments. To address the extent that products of indoor chemistry affect human health, the National Institute for Occupational Safety and Health sponsored a workshop titled "Indoor Chemistry and Health" on 12-15 July 2004 at the University of California-Santa Cruz. Weschler et al. (p. 442) present the issues discussed at the workshop and the priority research needs identified by the attendees.
Children's Health
HEALTH POLICY | America's Children and the Environment
There is a need for systematic approaches to assessment of environmental factors most relevant to health, health outcomes most influenced by the environment, and the relationships between them, as well as for approaches to representing the results of such assessments in policy deliberations. Kyle et al. (p. 447) used findings and data from the environmental protection and public health sectors to develop a set of measures representing topics relevant to children's environmental health. They present scientifically based representations of data understandable to stakeholders and policy makers that integrate key information from the health and environment sectors in a consistent format.
EXPOSURE ASSESSMENT | Children's Exposure to Multiple Chemicals
Sexton et al. (p. 453) assessed concurrent exposure to a mixture of environmental chemicals by measuring the chemicals or their metabolites in the blood of 43 ethnically diverse children from a socioeconomically disadvantaged neighborhood in Minneapolis, Minnesota. Blood samples were analyzed for 11 volatile organic compounds (VOCs), 2 heavy metals (lead and mercury), 11 organochlorine pesticides or related compounds, and 30 polychlorinated biphenyl (PCB) congeners. The evidence suggests that many VOCs originated from common sources, as did many PCBs. Results demonstrate that cumulative exposures to multiple environmental carcinogens and neurotoxins can be comparatively high for children from a poor inner-city neighborhood.
EXPOSURE ASSESSMENT | Chromium on Children's Hands
Children's exposure to arsenic and chromium from playground equipment constructed with chromated copper arsenate (CCA)-treated wood is a potential concern because of children's hand-to-mouth activity. No previous study has directly measured Cr levels on the hands of children after playing in such playgrounds. Hamula et al. (p. 460) measured soluble and total Cr on the hands of children playing in CCA-treated playgrounds. Analysis indicates that Cr, copper, and As are more closely grouped together in CCA playgrounds than in non-CCA playgrounds. These results suggest that the elevated levels of Cr and As on children's hands are a result of direct contact with CCA wood.
EXPOSURE ASSESSMENT | Correlates of Blood Lead Levels
Lead exposure has been associated with intellectual impairment in children in a number of international studies. In India, nearly half of the children have elevated blood lead levels (BLLs); however, little is known about risk factors for these elevated BLLs. Jain and Hu (p. 466) conducted a retrospective cross-sectional analysis of data from the Indian National Family Health Survey, a population-based study conducted in 1998-1999. The study found various factors correlated with elevated BLLs in children. The correlation between > 95th percentile of weight/height and higher BLL may reflect an impact of lead exposure on body habitus.
PUBERTY | Altered Breast Development in Girls
The age at which breast development begins is reported to have declined over the last five decades. There is debate over whether this decline has actually occurred and what factors contribute to it. Guillette et al. (p. 471) examined a group of peripubertal girls from the Yaqui Valley of Sonora, Mexico. Girls from valley towns exhibited larger breast fields than girls living in the foothills who exhibited a similar background. Further, girls from valley towns displayed a poorly defined relationship between size and mammary gland development. These data suggest that studies examining mammary tissue growth and fat deposition should take into account environmental influences on these phenomena.