Environews
Some Enchanted Research
The vulnerability of our health to environmental pollutants is undeniable. As we are confronted by more and more external challenges to our physical health, community outreach constitutes an increasingly important resource for combating these problems. This month's NIEHS News (p. A304) describes how researchers at the New Mexico Center for Environmental Health Sciences are applying research on lung disease, cardiovascular disease, and skin cancer to community outreach initiatives aimed at securing a healthier future for those living in the Land of Enchantment.
Home Court Disadvantage?
For many, the word "home" conjures up images of comfort and safety. Unfortunately, not everyone has the luxury of living in a home environment that is comfortable and safe, and many homes pose severe health risks to their occupants. The Focus takes a look at disparities in the built environment that directly contribute to disparities in health, and also examines some novel and proactive projects designed to level the playing field and give more families a chance at a healthier home court advantage.
Housing, Holistically Speaking
Although all housing hazards are not created equal, it can be beneficial for long-term environmental health if they are addressed simultaneously. Recognizing that many of the health hazards found in homes are often intertwined, the housing health industry is responding by cultivating more responsive, versatile professionals to seek out and solve multiple problems rather than tackling one problem at a time. The Innovations (p. A320) discusses the development of this new holistic method of spotting and addressing housing hazards.
Research
Chromosomal Aberrations and Cancer Risk
Additional data are needed to better characterize chromosomal aberrations (CAs) in peripheral blood lymphocytes as a marker of cancer risk. Rossner et al. (p. 517) evaluated archived cytogenetic records of 11,834 subjects classified according to the percentiles of CA distribution and linked to the Czech national cancer registry. There was a significant association between overall cancer incidence and the presence of chromosome-type aberrations for high versus low CA levels. Stomach cancer was strongly associated with frequency of total CAs. The association between CA frequency and cancer risk might be limited to chromosome-type aberrations.
Mercury, Food Webs, and Marine Mammals
Booth and Zeller (p. 521) modeled the flow of methyl mercury in the Faroe Islands marine ecosystem and compared average human exposure from consumption of pilot whale meat and fish with current tolerable weekly intake (TWI) levels. Results indicate that high levels of methyl mercury in the diet of Faroe Islanders are driven by whale consumption and that climate change is likely to exacerbate the situation. The flow of mercury into the environment would need to be reduced by 50% to ensure levels of intake below the World Health Organization TWI levels, given current levels of whale consumption.
Developmental Exposure of Rats to Chlorpyrifos
Aldridge et al.(p. 527) administered 1 mg/kg/day chlorpyrifos (CPF) to rats on postnatal days 1-4, a regimen below the threshold for systemic toxicity. When tested in adulthood, CPF-exposed animals showed abnormalities in behavioral tests that involve serotonergic mechanisms. Results indicate that neonatal CPF exposures, classically thought to be subtoxic, produce lasting changes in serotonergic-related behaviors that resemble animal models of depression.
Human Neurobehavioral Effects and Styrene Exposure
Long-term exposure to styrene may exert effects on the nervous system that influence choice reaction time, color discrimination, and color arrangement tasks. Benignus et al. (p. 532) conducted a meta-analysis for the relationships between exposure (estimated from biomarkers) and effects on reaction time and color vision. Statistically significant relationships were demonstrated between cumulative styrene exposure and increased choice reaction time, as well as increased color confusion index. The same exposure history was predicted to increase the color confusion index by as much as 1.7 additional years of age in men.
Historical Comparison of Fluorochemicals in Human Blood
Olsen et al. (p. 539) investigated whether there has been a change in human blood concentrations of perfluorooctanesulfonate, perfluorooctanoate, and five other fluorochemicals since 1974. Blood samples were collected in 1974 (serum) and 1989 (plasma) from volunteer participants of a large community health study. Statistical analysis of paired samples indicated that serum concentrations were significantly higher in 1989 than in 1974. The data from 1989 were then compared with mean fluorochemical concentrations of serum samples collected in 2001. With one exception, there were no significant differences in mean fluorochemical concentrations between the 1989 and 2001 samples.
Gliomas and Farm Pesticide Exposure in Women
An excess of brain cancer has been noted in male farmers, but few studies have focused on women. Carreón et al. (p. 546) evaluated effects of rural exposures for 341 adult female glioma cases and 528 controls. After adjusting for age, education, and farm residence, the authors observed no association with glioma for exposure to arsenicals, benzoic acids, carbamates, chloroacetanilides, dinitroanilines, inorganics, organochlorines, organophosphates, phenoxys, triazines, or urea-based or estrogenic pesticides.
Risk-Based Advice for Contaminated Farmed Salmon
Several organic contaminants occur at elevated concentrations in farmed Atlantic salmon. Foran et al. (p. 552) present information on cancer and noncancer health risks of exposure to dioxins in farmed and wild salmon. Their analysis is based on a tolerable intake level for dioxin-like compounds and on risk estimates for human exposure to dioxins. Consumption of farmed salmon at relatively low frequencies results in elevated exposure to dioxins and dioxin-like compounds, with commensurate elevation in estimates of health risk.
Fluoroquinolone-Resistant Campylobacter from Chicken Products
In February 2002, two U.S. poultry companies pledged to stop using fluoroquinolones (FQs) for flock-wide treatment. One year later, Price et al. (p. 557) compared rates of FQ-resistant Campylobacter isolates on chicken products from these two companies and from two producers who claimed total abstention from antibiotic use. Results indicate that antibiotic-free brands were not more likely to be contaminated and that a high percentage of products from the two conventional brands were contaminated with FQ-resistant Campylobacter. FQ resistance may persist in the absence of FQ-selective pressure, and these strains contaminate a larger proportion of foods than reported previously. (Also see Science Selections, p. A325)
The Haddon Matrix and Public Health Readiness
State and local health departments face unprecedented challenges in preparing for, recognizing, and responding to threats to the public's health. Public health readiness and response can be conceptualized similarly for intentional attacks, natural disasters, and human-caused accidents. The federal government has adopted the all-hazards response model as its paradigm because this model reduces the need to create complex situation-specific preparedness. However, in practice, public health preparedness requires additional models. Barnett et al. (p. 561) propose to extend the use of the Haddon matrix--a conceptual model used in injury prevention and response strategies--for this purpose.
Effects of Aerial Swine Emissions
Schiffman et al. (p. 567) exposed human subjects to aerial emissions from a swine house at levels that could occur at varying distances downwind from a confined animal feeding operation. Measures of blood pressure, temperature, heart rate, respiratory rate, lung function, nasal inflammation, secretory immunity, mood, attention, and memory were correlated with measures of air quality. Short-term exposure to malodorous emissions from a swine house at levels expected downwind can induce clinically important symptoms in healthy human volunteers.
Environmental Medicine
Ascorbate Depletion and Nickel Carcinogenesis
Nickel compounds cause respiratory cancer in humans and tumors in experimental animals. Salnikow and Kasprzak (p. 577) challenge the premise that direct genotoxic effects are central to nickel carcinogenesis, and propose that the formation of metal complexes with proteins and other molecules changes cellular homeostasis and provides conditions for selection of cells with transformed phenotype. The authors suggest that depletion of ascorbate by chronic exposure to nickel could be deleterious for lung cells and may lead to lung cancer.
Two Outbreaks of Occupationally Acquired Histoplasmosis
Huhn et al.(p. 585) studied the etiology and risk factors for acute histoplasmosis in two outbreaks in Illinois. Results indicated that workers performing activities that aerosolized topsoil and dust were at increased risk for acquiring histoplasmosis. Workers should wear personal protective equipment and use dust-suppression techniques when working in areas potentially contaminated with bird or bat droppings.
Children's Health
Cost of Methyl Mercury Toxicity to the Developing Brain
Developmental exposure to methyl mercury results primarily from consumption by pregnant women of seafood contaminated by mercury from anthropogenic and natural sources. Trasande et al. (p. 590) used national blood mercury prevalence data to determine that between 316,588 and 637,233 children each year have cord blood mercury levels > 5.8 µg/L, a level associated with loss of intelligence that persists for life. The resulting lost productivity is the major cost of methyl mercury toxicity, amounting to $8.7 billion annually (range, $2.2-43.8 billion; all costs are in 2000 US$). Of this total, $1.3 billion (range, $0.1-6.5 billion) each year is attributable to mercury emissions from American power plants.
IQ and Residual Blood Lead in Children
Increases in peak blood lead concentrations, which occur at 18-30 months of age in the United States, are thought to result in lower IQ scores at 4-6 years of age, when IQ becomes stable and measurable. Chen et al. (p. 597) analyzed data from children treated for elevated blood lead concentrations (20-44 µg/dL) at about 2 years of age and followed the children until 7 years of age with serial IQ tests and measurements of blood lead. Cross-sectional associations increased as the children became older, whereas the relation between baseline blood lead and IQ attenuated. Peak blood lead level does not fully account for the observed association between lower blood lead level and IQ in older children. (Also see Science Selections, p. A324)
A Time-Series Analysis of Air Pollution and Preterm Birth
Using a time-series analysis, which reduces confounding, Sagiv et al. (p. 602) investigated the effect of ambient outdoor particulate matter with diameter ≤ 10 µm (PM10) and sulfur dioxide on risk for preterm delivery. Adjusting for long-term preterm delivery trends and copollutants, and offsetting by the number of gestations at risk, the authors found increased risk for preterm delivery with exposure to average PM10 and SO2 in the 6 weeks before birth. They also found an acute effect of exposure to PM10 2 days and 5 days before birth.
Acute Respiratory Diseases and Carboxyhemoglobin in Children
High concentrations of carbon monoxide occur in areas with heavy traffic congestion. CO binds to hemoglobin to form carboxyhemoglobin (COHb), reducing oxygen delivery. Estrella et al.(p. 607) investigated the link between acute respiratory infections (ARIs) and COHb concentrations in school-age children living in urban and suburban areas of Quito, Ecuador. For each percent increase in COHb above the safety level, children were 1.15 times more likely to have an additional case of ARI. The findings provide strong evidence of the relation between CO exposure and respiratory infections.
Toxicogenomics
DEP Effects on Gene Expression
Rao et al. (p. 612) instilled diesel exhaust particles (DEPs) into rats intratracheally and studied postexposure gene expression in cells obtained by bronchoalveolar lavage (BAL) and in lung tissue. The cellular content in BAL fluid increased at all doses and at all time periods, mainly due to an increase in polymorphonuclear leukocytes. In vitro studies in alveolar macrophages and cultured lung fibroblasts showed that lung fibroblasts are a significant source of interleukin-6 and monocyte chemoattractant protein-1 in the lung.
Mini-Monograph
Brevetoxins Mini-Monograph
Florida red tide is caused by Karenia brevis, a dinoflagellate that periodically blooms, releasing its potent neurotoxin, brevetoxin, into the surrounding waters and air along the coast of the Gulf of Mexico. Exposure to Florida red tide toxins is associated with adverse human health effects and massive fish and marine mammal deaths. The Mini-Monograph (p. 618, 621, 626, 632, 638, 644, and 650) describes programs that characterize the exposures and health effects of aerosolized brevetoxins, using animal models and laboratory studies to apply findings to human exposures. The goal is to develop prevention and medical interventions to reduce adverse health effects. (Also see Science Selections, p. A324)
