Environews
NIEHS NEWS | Partners for Progress
When it comes to human and environmental health research, staying connected is key to staying on top of the latest information and advances. One way most experts keep a stable connection is through established journals that publish credible, peer-reviewed research, but in developing areas of the world such as Africa where funding and resources are scarce, the connection can be tenuous at best. This article (p. A452) takes a look at the strides being made by an international partnership created to increase the publishing efficiency, credibility, and scope of African research journals.
FOCUS | Land of Imperviousness
The United States is a land of extremes. Our roads are longer and wider, our parking lots are bigger and more numerous, and our suburbs sprawl farther than those of nearly any other country. In fact, impervious surfaces in America cover more than 43,000 square miles. The runoff from these surfaces poses a substantial threat to our environment. This article (p. A456) examines the environmental problems associated with runoff from paved surfaces, and discusses some possible solutions.
SPHERES OF INFLUENCE | Toward Becoming Sewer-Savvy
When combined sewer systems were introduced 150 years ago, they marked a major advance in dealing with wastewater. Today, these systems are outdated and often unable to handle the demands that modern populations place upon them; so-called combined sewer overflows result when stormwater and raw sewage together overwhelm the system. Although environmentalists and municipalities favor greater federal investment in sewer system upgrades, present federal budget realities indicate that the cost of improving current treatment systems could fall increasingly on localities and states. This article (p. A464) discusses some of the costs and concerns associated with combined sewer systems.
INNOVATIONS | Buzzworthy Mosquito Repellents
In addition to being a buzzing, itch-inducing nuisance, mosquitoes spread dangerous diseases to millions throughout the world. Researchers continue to seek better repellents to battle these tiny insects that create such large problems. The key to controlling their bite might lie in neutralizing their sense of smell. This article (p. A468) examines a new generation of mosquito repellents that will target specific genes in the insects' olfactory system.
Commentaries
TOXICOLOGY | Vinyl Chloride: A Case Study
When the U.S. Environmental Protection Agency (EPA) finalized its 2000 update of the toxicologic effects of vinyl chloride (VC), it was concerned with the classification of VC as a carcinogen and the numerical estimate of its potency. In their commentary, Sass et al. (p. 809) suggest that the U.S. EPA review of VC toxicology may have weakened safeguards by neglecting risks from all cancer sites other than the liver and by reducing the estimate of cancer potency 10-fold from values previously used for environmental decision making.
ETHICS | Pesticide Testing on Human Subjects
Two distinct positions have emerged in the debate about testing pesticides on human subjects: One position holds that pesticide experiments on human subjects should be allowed, but only under stringent scientific and ethical standards, and the other asserts that these experiments should never be allowed. Resnik and Portier (p. 813) evaluate the strongest argument for the second position--that the benefits do not justify the risks--and argue that a study that intentionally exposes humans subjects to pesticides should be permitted if a) the knowledge gained promotes human health; b) the knowledge cannot be obtained by other means; c) the study is not expected to cause harm to the subjects; and d) appropriate safeguards are in place.
TOXICOGENOMICS | Toxicogenomics and the Public Interest
Despite major advances in the science and technology of new toxicogenomics tools, scientific and political complexities threaten to delay the use of toxicogenomics to further the public interest or--worse--to advance its use initially to weaken the regulation and safety of widely used chemicals. Balbus (p. 818) interviewed experts from a variety of disciplines and sectors who agree that the promise of the new toxicology will be realized only if technical and political obstacles can be overcome. The scientific and public-interest communities must ensure that inappropriate definitions of rigor, as well as proprietary interests, do not hinder effective public health protection.
Reviews
NANOTECHNOLOGY | Nanotoxicology
Exposure exposed to airborne nanosized particles (NSPs; < 100 nm) has increased dramatically over the last century due to anthropogenic sources. Oberdörster et al. (p. 823) review biokinetic and toxicologic studies with airborne ultrafine particles as the basis for safety evaluation of engineered nanostructures and nanodevices. Considerations include selections of appropriate and relevant doses/concentrations, the likelihood of increased effects in a compromised organism, and the benefits of possible desirable effects. An interdisciplinary team approach (e.g., toxicology, materials science, medicine, molecular biology, and bioinformatics) is mandatory for nanotoxicology research to arrive at an appropriate risk assessment.
EXPOSURE ASSESSMENT | Personalized Exposure Assessment
New technologies and methods for assessing human exposure to stressors provide an opportunity to advance our understanding of the relationship between environmental exposure and disease. Weis et al. (p. 840) present a conceptual framework for moving these technologies into use and acceptance by the scientific community. The framework focuses on understanding complex human diseases using an integrated approach to exposure assessment to define particular exposure-disease relationships and the interaction of genetic and environmental factors in disease occurrence
Research
RESPIRATORY DISEASE | Changes in Levels of Nerve Growth Factor
Patients complaining of upper and lower airway symptoms caused by scents and chemicals have increased cough sensitivity to inhaled capsaicin, but the precise mechanisms behind this reaction are unknown. Millqvist et al. (p. 849) measured levels of nerve growth factor (NGF) in nasal lavage fluid before and after capsaicin inhalation provocations and related the capsaicin cough sensitivity to the NGF levels. The findings demonstrate that, in patients with airway symptom induced by scents and chemicals, sensory hyperreactivity is real and measurable, showing a pathophysiology in the airways of these patients compared to healthy subjects.
RISK CHARACTERIZATION | Lipid Adjustment and Risk Estimation
The literature on exposure to lipophilic agents such as polychlorinated biphenyls (PCBs) is conflicting and poses challenges for interpretation of human health risks. Laboratory variation in quantifying PCBs may account for some of the conflicting study results. Schisterman et al. (p. 853) evaluated four statistical models (unadjusted, standardized, adjusted, and two-stage) for the analysis of PCB exposure, serum lipids, and health outcome risk (breast cancer). Statistical models that deviated from underlying causal assumptions generated biased results. Lipid standardization, or the division of serum concentrations by serum lipids, was highly prone to bias.
REPRODUCTIVE HEALTH | Serum Dioxin and Age at Menopause
Studies in rats and monkeys suggest that 2,3,7,8-tetrachlorobenzo-p-dioxin (TCDD) may affect ovarian function. Eskenazi et al. (p. 858) examined the relationship of TCDD and age at menopause among women residing near Seveso, Italy, in 1976, at the time of a chemical plant explosion. All women were premenopausal at the time of the explosion and had TCDD levels measured in serum collected soon after the explosion. The results suggest a nonmonotonic dose-related association with increasing risk of earlier menopause up to about 100 ppt TCDD, but not above.
EXPOSURE ASSESSMENT | Household Water Use and Trihalomethane Exposure
Individual exposure to trihalomethanes (THMs) in tap water can occur through ingestion, inhalation, or dermal exposure. Nuckols et al. (p. 863) measured blood and exhaled air concentrations of THM as biomarkers of exposure among participants conducting common household water use activities at a single residence in each of two water utility service areas. All hot water use activities yielded a 2-fold increase in blood or breath THM concentrations for at least one individual. The greatest observed increase in blood and exhaled breath THM was due to showering, bathing, and hand dish washing. The average increase in blood THM concentration due to these activities ranged from 57 to 358 pg/mL.
Also see Science Selections, p. A474
NEURODEVELOPMENT | PCBs Disturb Differentiation of NHNP Cells
Children who are exposed to polychlorinated biphenyls (PCBs) during development may suffer from neuropsychologic deficits. It has been speculated that PCBs may affect brain development by interfering with thyroid hormone (TH) signaling. Fritsche et al. (p. 871) established a model using primary normal human neural progenitor (NHNP) cells to determine if PCBs interfere with TH-dependent neural differentiation. NHNP cells differentiate into neurons, astrocytes, and oligodendrocytes in culture. Like triiodothyronine (T3), treatment with the mono-ortho-substituted PCB-118 (2,3´,4,4´,5-pentachlorobiphenyl) leads to a dose-dependent increase of oligodendrocyte formation. The coplanar PCB-126 (3,3´,4,4´,5-pentachlorobiphenyl) had no effect. These results suggest that PCB-118 mimics T3 action via the TH pathway.
Also see Science Selections, p. A472
Environmental Medicine
NEUROBEHAVIORAL DISEASE | Neurologic Symptoms in Licensed Pesticide Applicators
Little is known about the neurotoxicity of chronic exposure to moderate levels of pesticides. Kamel et al. (p. 877) analyzed cross-sectional data on lifetime pesticide use and neurologic symptoms from pesticide applicators enrolled in the Agricultural Health Study in 1993-1997. Results suggest that self-reported neurologic symptoms are associated with cumulative exposure to moderate levels of fumigants and organophosphate and organochlorine insecticides, regardless of recent exposure or history of poisoning.
Also see Science Selections, p. A472
CARDIOVASCULAR DISEASE | Air Pollution and ST-Segment Depression
Increased levels of daily ambient particle pollution are associated with increased risk of cardiovascular morbidity. Gold et al. (p. 883) investigated associations between ambient pollution and ST-segment levels in a repeated-measures study of active Boston residents 61-88 years of age. The protocol involved continuous Holter electrocardiogram monitoring during various activities. During postexercise rest, an elevated black carbon (BC) level was associated with -0.1 mm ST-segment depression for 12-hr mean BC in continuous models. Elevated BC also predicted increased risk of ST-segment depression among those with at least one episode of that level of ST-segment depression.
ASTHMA | Grand Rounds: Latex-Induced Occupational Asthma
Green-McKenzie and Hudes (p. 888) present the case of a 46-year-old surgical pathologist with increasing shortness of breath for the previous 4 years. At presentation, he had one-flight dyspnea, his skin prick test was positive for latex, and pulmonary function testing showed mild obstruction, which was reversible with bronchodilator use. The patient's presentation is consistent with latex-induced occupational asthma. Initially he noted dermal manifestations, consistent with an allergic contact dermatitis secondary to accelerators present in latex gloves; he later developed urticaria, flushing, and respiratory symptoms, consistent with a type I hypersensitivity reaction to latex. Clinicians should consider occupational asthma when patients present with new-onset asthma or asthmatic symptoms that worsen at work.
Children's Health
NEURODEVELOPMENT | Childhood Lead Exposure and Intellectual Function
Questions remain about lead-associated intellectual deficits at blood lead levels < 10 µg/dL and whether lower exposures are, for a given change in exposure, associated with greater deficits. Lanphear et al. (p. 894) examine the association of intelligence test scores and blood lead concentration for children using the full-scale IQ score as the primary outcome measure. Using a log-linear model, they found a 6.9 IQ point decrement associated with an increase in concurrent blood lead levels from 2.4 to 30 µg/dL. The estimated IQ point decrements associated with an increase in blood lead from 2.4 to 10 µg/dL, 10 to 20 µg/dL, and 20 to 30 µg/dL were 3.9, 1.9, and 1.1 respectively. The lead-associated intellectual decrement for children with a maximal blood lead level < 7.5 µg/dL was significantly greater than that observed for those with a maximal blood lead level > 7.5 µg/dL.
Also see Science Selections, p. A473
RESPIRATORY DISEASE | Blood Lead Level and Risk of Asthma
Lead exposure may be associated with excessive production of immunoglobulin E, possibly increasing asthma risk and contributing to racial disparities. Joseph et al. (p. 900) examined racial differences in the association of blood lead level to risk of developing asthma. When compared with Caucasians with blood lead level < 5 µg/dL, African Americans were at a significantly increased risk of asthma regardless of BLL. An effect of blood lead level on risk of asthma for African Americans was not observed. Results demonstrate the need for further exploration of the complex interrelationships between race, asthma phenotype, genetic susceptibilities, and socioenvironmental exposures, including lead.
EXPOSURE ASSESSMENT | Umbilical Cord Mercury as Exposure Biomarker
A prospective study in the Faroe Islands used mercury concentrations in cord blood and maternal hair obtained at parturition as the main biomarkers of mercury exposure. Grandjean et al. (p. 905) supplemented these exposure biomarkers with analyses of mercury in umbilical cord tissue. When expressed in relation to the dry weight of the tissue, the cord mercury concentration correlated very well with that in cord blood. Cord mercury analysis can therefore be used as a valid measure of prenatal methylmercury exposure, but appropriate adjustment for imprecision should be considered.
CANCER | Child Brain Tumors and PON1 Insecticide Metabolism
Searles Nielsen et al. (p. 909) investigated whether two common P450/paraoxonase 1 (PON1) pathway polymorphisms, C-108T and Q192R, are associated with childhood brain tumor (CBT) occurrence using a population-based case-control study linking DNA from neonatal screening archive specimens to interview data. Results are consistent with an inverse association between PON1 levels and CBT occurrence, perhaps because of PON1's ability to detoxify organophosphorus insecticides common in children's environments. Larger studies that measure plasma PON1 levels and incorporate more accurate estimates of pesticide exposure will be required to confirm these observations.
