Environews
NIEHS NEWS | Change of Venue
International conferences have long served as meeting places for members of the scientific community to gather and share information and ideas. Connections made at these meetings often lead to collaborations that benefit the attendees' home regions, but since many of the more established conferences are held in some of the world's most prominent cities, those most in need of the science often have trouble gaining access to it. This article (p. A696) takes a look at the International Conference on Environmental Mutagens in Human Populations series, cosponsored by the NIEHS, which brings environmental mutagen health research and outreach to scientists in less-developed areas of the world.
FOCUS | Signs of the Times: Biomarkers in Perspective
As environmental health science research has continued to evolve, there has been a shift from population-based studies to investigations that focus more on individual susceptibility to disease. Researchers believe that understanding the impacts of personal exposures could be key in combating illnesses that affect us all, and they rely on the identification of biomarkers to measure health status from initial exposure through the development of health effects. This article (p. A700) examines some early breakthroughs made in biomarker research, discusses current strides being made in the identification and application of effective biomarkers, and looks ahead to future research directions.
SPHERES OF INFLUENCE | Obstructing Authority: Does the EPA Have the Power to Ensure Commercial Chemicals Are Safe?
Since the late 1970s, the EPA has regulated chemical use through the Toxic Substances Control Act (TSCA), which mandates that industry report on all current chemicals used in U.S. products as well as gain EPA approval for the manufacture of new chemicals. But does TSCA give the EPA enough power to adequately protect our health and our environment? This article (p. A706) discusses some of the issues raised in a new report by the Government Accountability Office, which calls for an update of TSCA guidelines to strengthen the EPA's regulatory powers.
INNOVATIONS | Fluid Movement
The emerging field of microfluidics—the analysis of fluids on the microlevel—could improve investigations across a wide spectrum of applications in medicine and environmental health. One challenge researchers face in this technology is controlling droplet motion, and they are now working on new methods to control droplet flow on surfaces and through channels. This article (p. A710) looks at a new superhydrophobic magnetic surface developed by an Arizona State University research team that could lead to more refined results in an even broader range of applications.
Commentaries
TOXICOLOGY | Inert Ingredients in Pesticides
By statute or regulation in the United States and elsewhere, pesticide ingredients are divided into two categories: active and inert (sometimes referred to as other ingredients, adjuvants, or coformulants). Despite their name, inert ingredients may be biologically or chemically active and are labeled inert only because of their function in the formulated product. Inert ingredients are generally not identified on product labels and are often claimed to be confidential business information. Cox and Surgan (p. 1803) describe the shortcomings of the current procedures for assessing the hazards of pesticide formulations and demonstrate that inert ingredients can increase the toxicity of and potential exposure to pesticide formulations.
CLIMATE CHANGE | What Can Be Done about Climate Change Now?
The debate about whether global environmental change is real is over, but change is happening more rapidly than predicted. The changes constitute a profound challenge to human health, both as a direct threat and as a promoter of other risks. Schwartz et al. (p. 1807) call on health care providers to inform themselves and to become agents of change in their communities. They urge political, business, public health, and academic leaders to heed the environmental warnings and quickly develop regulatory and policy solutions so that the health of populations and the integrity of their environments will be ensured for future generations.
HEALTH POLICY | Prioritizing World Environmental Health Concerns
As the next generation of scientists enters the field of environmental health, it is imperative that they view their contributions in the context of global environmental stewardship. In this commentary, international graduate students facilitated by three experienced environmental health scientists present their views on what they consider to be the global environmental health concerns of today. This group convened initially in October 2004 at an international health conference in Prague, Czech Republic. Craft et al. (p. 1813) identify perceived environmental health concerns that exist around the world, with a focus on Central and Eastern Europe. Additionally, they address these perceived problems and offer some potential solutions.
Review
NANOTECHNOLOGY | Health Effects of Nanoparticles
With the advent of nanotechnology, the prospects for using engineered nanomaterials with diameters of < 100 nm in industrial applications, medical imaging, disease diagnoses, drug delivery, cancer treatment, gene therapy, and other areas have progressed rapidly. The potential for nanoparticles in these areas is infinite, and novel new applications are constantly being explored. Many fine particles that are generally considered "nuisance dusts" are likely to acquire unique surface properties when engineered to nanosize and may exhibit toxic biological effects. Gwinn and Vallyathan (p. 1818) highlight the possible toxic human health effects that can result from exposure to ultrafine particles generated by anthropogenic activities and their cardiopulmonary outcomes.
Research
EXPOSURE ASSESSMENT | Arsenic Bioavailability in Rice
Millions of people worldwide consume arsenic-contaminated rice, but little is known about the uptake and bioavailability of arsenic species after ingestion of this rice. Juhasz et al. (p. 1826) assessed arsenic speciation in greenhouse-grown and supermarket-bought rice, and determined arsenic bioavailability in cooked rice using an in vivo swine model. Results indicate that arsenic bioavailability is highly dependent on arsenic speciation, which can vary depending on rice cultivar, arsenic in irrigation water, and the presence and nature of arsenic speciation in cooking water. Arsenic speciation and bioavailability are critical parameters for reducing uncertainties when estimating exposure from the consumption of rice grown and cooked using arsenic-contaminated water.
TOXICOLOGY | Arsenite Increases Cellular Uptake of Benzo[a]pyrene Diol Epoxide
Arsenite (iAsIII) can promote mutagenicity and carcinogenicity of other carcinogens. Considerable attention has focused on the interference of inorganic arsenic with DNA repair, especially the nucleotide excision repair pathway, but less is known about how arsenic affects the induction of DNA damage by other agents. Shen et al. (p. 1832) suggest that iAsIII enhances the formation of benzo[a]pyrene diol epoxide (BPDE)–DNA adducts by increasing the cellular uptake of BPDE. Therefore, the ability of arsenic to increase the bioavailability of other carcinogens may contribute to arsenic co-carcinogenicity.
CANCER | Occupational Fonofos Exposure and Incident Cancer
The Agricultural Health Study (AHS) is a prospective cohort study of licensed pesticide applicators from Iowa and North Carolina enrolled in 1993–1997 and followed for incident cancer through 2002. A previous investigation linked exposure to the organophosphate fonofos with incident prostate cancer in subjects with family history of prostate cancer. This finding along with findings of associations between organophosphate pesticides and cancer led Mahajan et al. (p. 1838) to study fonofos and the risk of any cancers among 45,372 pesticide applicators enrolled in the AHS. Further study is warranted to confirm findings with respect to leukemia and determine whether genetic susceptibility modifies prostate cancer risk.
BIOMARKERS | Parabens as Biomarkers of Exposure
Studies have revealed that some parabens, which appear frequently as antimicrobial preservatives in cosmetic products, in pharmaceuticals, and in food and beverage processing, have weak estrogenic activity. Widespread use has raised concerns about the potential health risks associated with paraben exposure. Ye et al. (p. 1843) evaluated the use of free and conjugated parent parabens as new biomarkers for human exposure to these compounds. The results demonstrate the presence of urinary conjugates of parabens in humans, suggesting that such conjugated parabens could be used as biomarkers of exposure. Additionally, the fact that conjugates appear to be the main urinary products of parabens may be important for risk assessment.
Also see Science Selections, p. A714
RISK CHARACTERIZATION | Arsenic-Related Skin Lesions by Age and Sex
In this population-based case–referent study in Matlab, Bangladesh, Rahman et al. (p. 1847) assessed the susceptibility to arsenic-induced skin lesions by age and sex in a population drinking water from As-contaminated tube wells. They found a dose–response relationship for both sexes and increased risk with increasing socioeconomic status. Males had a higher risk of developing skin lesions than females in the highest average exposure quintile. Start of As exposure before 1 year of age was not associated with higher risk of developing skin lesions compared to start of As exposure later in life.
RESPIRATORY DISEASE | The WTC Disaster and the Health of Workers: Five-Year Assessment
Approximately 40,000 rescue and recovery workers were exposed to caustic dust and toxic pollutants after the 11 September 2001 attacks on the World Trade Center (WTC). To characterize WTC-related health effects, the WTC Worker and Volunteer Medical Screening Program was established. Herbert et al. (p. 1853) report thatWTC responders had exposure-related increases in respiratory symptoms and pulmonary function test abnormalities that persisted up to 2.5 years after the attacks. Long-term medical monitoring is required to track persistence of these abnormalities and identify late effects, including possible malignancies. The lessons learned should guide future responses to civil disasters.
INFECTIOUS DISEASE | Antibiotic-Resistant Residential Indoor Bioaerosols
Gandara et al. (p. 1859) evaluated the levels of Staphylococcus aureus and antibiotic-resistant S. aureus in colony-forming units per cubic meter of air. The study indicates that antibiotic-resistant bioaerosols are commonly found within residences. The results also suggest that resistant strains of airborne culturable S. aureus were present in higher concentrations inside the study homes than outside the homes.
Also see Science Selections, p. A715
ENDOCRINE SYSTEM | Perchlorate and Thyroid Function, NHANES 2001–2002
Perchlorate is commonly found in the environment and is known to inhibit thyroid function at high doses. Assessing the potential effect of low-level exposure to perchlorate is an area of ongoing research. Blount et al. (p. 1865) evaluated the potential relationship between urinary levels of perchlorate and serum levels of thyroid stimulating hormone (TSH) and total thyroxine (T4) in men and women who participated in the National Health and Nutrition Examination Survey during 2001–2002. The associations of perchlorate with T4 and TSH are coherent in direction and independent of other variables, but are present at perchlorate exposure levels that were unanticipated based on previous studies.
Also see Science Selections, p. A714
NEURODEGENERATIVE DISEASE | Occupational Lead Exposure and Parkinson's Disease
Several epidemiologic studies have suggested an association between Parkinson's disease (PD) and exposure to heavy metals using subjective exposure measurements. Coon et al. (p. 1872) investigated the association between chronic occupational lead exposure and the risk of PD. Risk of PD was elevated by > 2-fold for individuals in the highest quartile for lifetime lead exposure relative to the lowest quartile, adjusting for age, sex, race, smoking history, and coffee and alcohol consumption. These results provide an objective measure of chronic Pb exposure and confirm earlier findings that occupational exposure to Pb is a risk factor for PD.
RISK ASSESSMENT | Pollutant Mixtures
Many investigations of the adverse health effects of multiple air pollutants analyze the time series involved by simultaneously entering the multiple pollutants into a Poisson log-linear model. Because this method can yield unstable parameter estimates when the pollutants involved suffer high intercorrelation, traditional approaches to dealing with multicollinearity, such as principal component analysis (PCA), have been promoted in this context. A characteristic of PCA is that its construction does not take into account the relationship between the covariates and the adverse health outcomes. Roberts and Martin (p. 1877) propose a refined version of PCA—supervised PCA—that specifically addresses this issue.
REMEDIATION | Mold and Endotoxin in New Orleans Houses
After Hurricane Katrina, many New Orleans homes remained flooded for weeks, promoting heavy microbial growth. In November 2005–January 2006, a demonstration project was conducted aiming to recommend safe remediation techniques and safe levels of worker protection, and to characterize airborne mold and endotoxin throughout cleanup. During baseline and intervention, mold and endotoxin levels were similar to those found in agricultural environments. Chew et al.(p. 1883) strongly recommend that those entering, cleaning, and repairing flood-damaged homes wear respirators at least as protective as elastomeric respirators. Recommendations based on this demonstration will benefit those involved in the current cleanup activities and will inform efforts to respond to future disasters.
EXPOSURE ASSESSMENT | Tobacco Industry SHS Study Supports Smoke-free Work
Since 1996, the tobacco industry has used conclusions from the 16 Cities Study conclusions that workplace secondhand tobacco smoke (SHS) exposures are lower than home exposures to argue that workplace and other smoking restrictions are unnecessary. Barnes et al.'s(p. 1890) goal was to determine the origins and objectives of the 16 Cities Study through analysis of internal tobacco industry documents and regulatory agency and court records, and to evaluate the validity of the study's conclusions. Data from the 16 Cities Study reveal that smoke-free workplaces would dramatically reduce total SHS exposure, providing significant worker and public health benefits.
HEALTH POLICY | Aflatoxins in Developing Countries
In response to consecutive outbreaks of acute aflatoxicosis in Kenya that caused > 150 deaths, the Centers for Disease Control and Prevention and the World Health Organization convened a workgroup of experts and health officials. Strosnider et al. (p. 1898) expand on the workgroup's discussions concerning developing countries and summarize their findings. The workgroup identified gaps in current knowledge about acute and chronic health effects of aflatoxins, surveillance and food monitoring, analytic methods, and the efficacy of intervention strategies. The workgroup also identified public health strategies that could be integrated with current agricultural approaches to resolve gaps in knowledge and ultimately reduce morbidity and mortality associated with the consumption of contaminated food in the developing world.
Children's Health
NEURODEVELOPMENT | Environmental Toxicant Exposures and ADHD
In order to examine the association of exposures to tobacco smoke and environmental lead with attention deficit hyperactivity disorder (ADHD), Braun et al.(p. 1904) obtained data from the National Health and Nutrition Examination Survey 1999–2002. Prenatal and postnatal tobacco smoke exposure was based on parent report, and Pb exposure was measured using blood Pb concentration. ADHD was categorized as having current stimulant medication use and parent's report of ADHD diagnosed by a doctor or health professional. The authors conclude that prenatal tobacco smoke and environmental Pb exposures are risk factors for ADHD in U.S. children.
Also see Science Selections, p. A715
ASTHMA | Dogs, Air Pollution, and Asthma
Experimental data suggest that asthma exacerbation by ambient air pollutants is enhanced by exposure to endotoxin and allergens, but there is little supporting epidemiologic evidence. McConnell et al. (p. 1910) evaluated whether the association of exposure to air pollution with annual prevalence of chronic cough, phlegm production, or bronchitis was modified by dog and cat ownership. The study population consisted of 475 Southern California children with asthma from a longitudinal cohort of participants in the Southern California Children's Health Study. The results suggest that dog ownership, a source of residential exposure to endotoxin, may worsen the relationship between air pollution and respiratory symptoms in asthmatic children.
IMMUNOLOGY | Th1/Th2 Cytokines in Children of Agricultural Workers
Children who reside in agricultural settings are potentially exposed to higher levels of organophosphate pesticides, endotoxin, and allergens than their urban counterparts. Duramad et al. (p. 1916) investigated the relationships between these exposures and T-helper 1 (Th1) and T-helper 2 (Th2) cytokines, biomarkers of allergic asthma, in the subjects of the Center for the Health Assessment of Mothers and Children of Salinas. Asthma and wheeze outcomes in children at 24 months of age are associated with elevated Th2 status in young children. The data suggest that early exposures to an agricultural environment, breast milk, pets, and gas stoves affect the development of children's Th1/Th2 immune response.
NEUROBEHAVIORAL DISEASE | Response Inhibition, DRL, and Toxicant Exposure
Animal studies have shown that exposure to common, low-level environmental contaminants [e.g., polychlorinated biphenyls (PCBs), lead] causes excessive and inappropriate responding on intermittent reinforcement schedules. The Differential Reinforcement of Low rates task (DRL) has been shown to be especially sensitive to low-level PCB exposure in monkeys. Stewart et al. (p. 1923) investigated the relationships between prenatal PCB and postnatal Pb exposure performance on a DRL schedule in children. The results, taken with animal literature, argue the high sensitivity of DRL performance to low-level PCB, methylmercury, and Pb exposure.
Mini-Monograph
CLIMATE CHANGE | Assessing Vulnerability to Climate Change
Small island states are most vulnerable to climate variability and long-term climate change. To better understand the potential human health consequences of the projected results of long-term climate change, a series of workshops and a conference organized by the World Health Organization, in partnership with the World Meteorological Organization and the United Nations Environment Programme, addressed the following issues: the current distribution and burden of climate-sensitive diseases in small island states, the potential future health impacts of climate variability and change, the interventions currently used to reduce the burden of climate-sensitive diseases, additional interventions that are needed to adapt to current and future health impacts, and the health implications of climate variability and change in other sectors. The mini-monograph (p. 1930) provides information on these issues and identifies key recommendations for improving the capacity of the health sector to anticipate and prepare for climate variability and change in small island states.