Environews
NTP: The Road to Come
After 25 years, the National Toxicology Program (NTP) has no intentional of resting on its laurels. The program is developing a "roadmap," described in this month's NIEHS News (p. A874), to guide the NTP in its research endeavors over the next decade. The program's goal? To raise toxicology from an observational science to a predictive one, in part through the use of state-of-the-art high-throughput technologies.
Environmental Cardiology: Talking Heart to Heart
Evidence has been building for decades that environmental agents such as particulate matter, heavy met als, and dioxins can affect heart health in a variety of ways. But only recently has the name "environmental cardiology" been applied to this area of study, and only recent has the field begun to be, well, wholeheartedly embraced. The Focus (p. A880) examines this evolving field and its move into mainstream medical and scientific discussion.
Is Coal the Next Comeback Kid?
The Spheres of Influence (p. A888) takes a look at the life and times of coal, a hardy survivor of a fuel--in fact, one of humankind's original fuels. After several decades of decline due in large part to environmental concerns, coal may be on its way back into greater use in the United States, if modern technology can make it possible to burn this readily available material cleanly enough.
Salvaging Forgotten Forests
Millions of trees lay forgotten underwater, sunk during log drives or submerged in the building of large dams. In cold enough waters, submerged timbers can remain sound indefinitely. Now a Canadian company has found a way to raise these forgotten forests from lake floors without disrupting the lake ecosystem. Their solution, described in the Innovations (p. A892), is a remote-controlled submarine known as the Sawfish.
Research
Listing Occupational Carcinogens
Lists of occupational carcinogens have been limited by unclear criteria and incomplete information on the occupations and industries in which the carcinogenic substances may be found and on their target sites. Siemiatycki et al. (p. 1447) summarize current knowledge on occupational carcinogens, the occupations and industries in which they are found, and their target organs. The authors recognize 28 agents as definite occupational carcinogens, 27 agents as probable occupational carcinogens, and 113 agents as possible occupational carcinogens.
Organochlorine Exposure and Colorectal Cancer Risk
Despite reductions in their use and release, organochlorines (OCs) remain one of the most important groups of persistent pollutants linked to increased risk of several cancers. Howsam et al. (p. 1460) conducted a case-control study to assess the risk of colorectal cancer with exposure to OCs, and their interactions with genetic alterations (K-ras and p53) in the tumors. An elevated risk of colorectal cancer was associated with higher serum concentrations of the mono-ortho PCBs 28 and 118.
Endocrine Disruption in Mussels from Singapore
Bayen et al. (p. 1467) present data on sex hormone activities in the green mussel (Perna viridis), a common indicator of marine contamination, collected from Singapore's coastal waters. Tissue extracts were screened for activities on androgen receptors (ARs) and estrogen receptors ( and ß) using a reporter gene bioassay in a HeLa human cell line. Mussel extracts alone did not exhibit AR activity, but in the presence of the reference androgenic hormone dihydrotestosterone (DHT), activities were up to 340.1% higher than those observed for DHT alone. Peak activities were observed in locations adjacent to industrial and shipping activities.
Cumulative Energy Intake Determines the Onset of Puberty in Female Rats
Laboratory animal diets can affect both control values and sensitivity in endocrine-disrupting assays. Odum et al. (p. 1472) investigated the relationship between cumulative energy intake and sexual maturation in female rats. Vaginal opening (VO) occurred at an energy intake of ~ 2,300 kJ/rat, determined by measuring total food intake from weaning to VO; this indicates that cumulative energy intake was the trigger for puberty. Metabolizable energy is therefore a critical factor in the choice of diets for endocrine-disruption studies.
Xenoestrogen-Induced ERK Activation
The failure of various in vitro or in vivo assays to show strong activity of xenoestrogens compared with estradiol makes it difficult to explain their ability to cause abnormalities in animals via this pathway of steroid action. Bulayeva and Watson (p. 1481) demonstrate that several xenoestrogens can rapidly activate extracellular signal-regulated protein kinases (ERKs) in the pituitary tumor cell line GH3/B6/F10, which expresses high levels of the membrane estrogen receptor ER-. Multiple inhibitors blocked ERK activation, differentially affecting each xenoestrogen response examined. (Also see Science Selections, p. A897)
Effects of Isoprene and Butadiene Photochemical Products
The carcinogenic air pollutant 1,3-butadiene (BD) and its 2-methyl analog, isoprene (ISO), are chemically similar, but the ISO form shows no significant carcinogenesis. Reactions induced by sunlight and nitrogen oxides convert airborne BD and ISO into several photochemical reaction products. Doyle et al. (p. 1488) determined the relative toxicity and inflammatory gene expression induced by exposure of A549 cells to BD, ISO, and their photochemical degradation products. Results indicate that while BD and ISO alone caused similar cytotoxicity and interleukin-8 (IL-8) response compared with the air control, their photochemical products significantly enhanced cytotoxicity and IL-8 gene expression.
Lead in Greenland
Blood lead levels have declined in Greenland, but they are still elevated despite the fact that lead levels in the Greenland environment are very low. Fragments of lead shot in game birds have been suggested as an important source of dietary exposure. In a cross-sectional population survey in Greenland in 1993-1994, Bjerregaard et al. (p. 1496) found blood lead concentration adjusted for age and sex was associated with the reported consumption of sea birds. Blood lead was not associated with dietary exposure to other local or imported food items.
Extra Calcium and Blood Lead in Pregnancy and Postpartum
Maternal bone turnover is accelerated during pregnancy and lactation. Gulson et al. (p. 1499) examined the potential protective effects of calcium supplementation during pregnancy and for 6 months postpartum. For subjects who receive enough calcium, the delayed increase in blood lead and the decrease in extra lead released from bone during late pregnancy and postpartum may provide less lead exposure to the developing fetus and newborn infant. Calcium supplementation appears to provide limited benefit for lead toxicity during lactation.
Androgen Production in Vitro and in River Sediment
The Fenholloway River in Florida receives paper mill effluent and contains masculinized female mosquitofish. Jenkins et al. (p. 1508) hypothesized that plant sterols (e.g., ß-sitosterol) are being transformed by bacteria into progesterone and subsequently into 17-hydroxyprogesterone, androstenedione, and other androgens. Study results indicate these same androgens can be produced in vitro from the bacterium Mycobacterium smegmatis. The presence of androstadienedione, a 1 steroid with androgen activity, has also been verified in the Fenholloway River.
Hepatic and Renal Toxicity of Environmental Cadmium and Lead
Satarug et al. (p. 1512) examined the relationships between hepatic cytochrome P450 2A6 (CYP2A6) phenotype, nephropathy, and exposure to cadmium and lead in healthy Thai men and women who had never smoked. A positive correlation between cadmium-linked nephropathy and CYP2A6 activity in men (r = 0.39; p = 0.002) and women (r = 0.37; p = 0.001) suggests that cadmium induction of hepatic CYP2A6 expression and cadmium-linked nephropathy occurred simultaneously.
Rodent Diet and Expression Profiling in Reproductive Tissue
Phytoestrogens are common in laboratory animal diets, and the effect of background phytoestrogens on the outcome of rodent bioassays is controversial. Naciff et al. (p. 1519) assessed estrogenic effects of dietary phytoestrogens on gene expression together with traditional biologic end points using estrogen-responsive tissues of the immature female rat. Results indicate that although diet composition has an impact on gene expression in the uterus and ovaries, it does not contribute to the effects of the estrogen receptor agonist 17-ethynyl estradiol.
Composition versus Toxicity of Motor Vehicle Emissions
McDonald et al. (p. 1527) used a combination of principal component analysis and partial least squares regression to evaluate the relationships between chemical composition of vehicle exhaust and toxicity, measured as inflammation and tissue damage in rat lungs and mutagenicity in bacteria. The specific nitro-polycyclic aromatic hydrocarbons important for mutagenicity were not associated with lung toxicity, which was associated with higher molecular weight particle-associated organic carbon, especially hopanes and steranes present in lubricating oil.
Lung Cancer in Railroad Workers Exposed to Diesel Exhaust
The assessment of lung cancer risk associated with diesel exhaust has been limited by the lack of studies of exposed workers followed for many years. Garshick et al. (p. 1539) examined lung cancer mortality among 54,973 U.S. railroad workers between 1959 and 1996. Lung cancer mortality was elevated in jobs associated with trains powered by diesel locomotives. Although a contribution from coal combustion products before 1959 cannot be excluded, these results suggest that diesel exhaust contributed to lung cancer mortality in this cohort.
Imaging of ER Activation in Utero
Environmental estrogens are of particular concern when exposure occurs during embryonic development, but developmental exposure is much more difficult to test. Lemmen et al. (p. 1544) have generated transgenic mice that carry estrogen-responsive elements coupled to luciferase. Using this in vivo model in combination with an imaging system, activation of estrogen receptors by maternally applied bisphenol A (BPA) and other estrogens can be detected in living embryos in utero. Results indicate that the estrogenic potency of BPA estimated using in vitro assays might underestimate its estrogenic potential in embryos. (Also see Science Selections, p. A896)
Spatial Clustering of SARS in Hong Kong
Lai et al. (p. 1550) analyzed the patterns of disease spread during the 2003 SARS (severe acute respiratory syndrome) outbreak in Hong Kong using geographic information system (GIS) technology. Elementary mapping of disease occurrences in space and time simultaneously revealed the geographic extent of spread throughout the territory and confirmed that SARS cases were highly clustered into distinct disease "hot spots." Origin-and-destination plots showed the directional bias and radius of spreading events. (Also see Science Selections, p. A896)
Climate Change and Ozone-Related Health Impacts
Knowlton et al. (p. 1557) developed and applied an integrated modeling framework to assess potential ozone-related health impacts in future decades under a changing climate. Changes in O3-related impacts on summer mortality resulting from climate change alone and with climate change superimposed on changes in O3 precursor emissions and population growth were assessed for five summers of the 2050s across the 31-county New York metropolitan region. Counties with the highest increases in projected O3 mortality spread beyond the urban core into less populated suburban counties.
Environmental Medicine
Induced Sputum in Firefighters Exposed to WTC Dust
New York City firefighters (FDNY-FFs) were exposed to particulate matter and combustion products during and after the World Trade Center (WTC) collapse. Ten months after the collapse, Fireman et al. (p. 1564) obtained induced sputum (IS) samples from 39 highly exposed FDNY-FFs and compared these samples to those from controls to determine whether a unique pattern of inflammation and particulate matter deposition was present. IS from highly exposed FDNY-FFs demonstrated inflammation, particle size distribution, and composition that was different from IS from nonexposed controls but was consistent with WTC dust exposure.
Children's Health
Cryptorchidism and Hypospadias
Little is known about environmental risk factors that contribute to cryptorchidism and hypospadias. Pierik et al. (p. 1570) studied risk factors for cryptorchidism and hypospadias, with a focus on endocrine disruptors in parental diet and occupation using a case-control study nested within a cohort of male births. Paternal pesticide exposure was associated with cryptorchidism, and paternal smoking was associated with hypospadias, suggesting that paternal exposure should be included in further studies.
Geographic Analysis of Blood Lead Levels
Haley and Talbot (p. 1577) examined the geographic distribution of blood lead levels (BLLs) of 677,112 children born between 1994 and 1997 in New York State and screened before 2 years of age. Older housing, a lower proportion of high school graduates, and a higher percentage of births to black mothers were the community characteristics most associated with elevated BLLs. Lead remains an environmental health problem in inner-city neighborhoods, particularly in upstate New York.
Housing and Health: Children at Risk
In November 2002, the National Center for Healthy Housing convened a 2-day workshop focused on the effect of housing on children's health and the translation of research findings into practical construction, rehabilitation, and maintenance. Breysse et al. (p. 1583) provide an overview suggesting that lack of consensus on standard measurements, incomplete understanding about the interaction of home hazards, inadequate research on the effectiveness of interventions, and insufficient political support limit current efforts to achieve healthy housing.
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Last Updated: October 14, 2004