Research

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Aerosolized Nanomaterials in Environmental Studies

Many laboratories are conducting research on engineered carbonaceous nanomaterials (CNMs) in environmentally relevant systems, but laboratory exposures during procedures used in this research have not been systematically evaluated. Johnson et al. (p. 49) measured the release of fullerenes (C60), underivatized multiwalled carbon nanotubes (raw MWCNT), hydroxylated MWCNT (MWCNT-OH), and carbon black (CB) into air as nanomaterials were weighed, suspended, and sonicated in water with and without natural organic matter (NOM; a natural surfactant used to simulate environmentally relevant matrices). Airborne particle number concentrations in the nanometer range (10-1,000 nm) and six specific size ranges (300-10,000 nm) were measured using two hand-held particle counters, and transmission electron microscopy was used to investigate the size and morphology of particles collected on air sample filters. The authors report that airborne particle number concentrations increased during weighing for each nanomaterial except CB, and increased during sonication, particularly when CB and MWCNT-OH were sonicated in water with NOM. Additional research is needed to fully characterize CNM releases, but the authors recommend the use of appropriate protective equipment and engineering controls to minimize exposures, including exposures to CNMs that may be released from liquid suspensions.

* Also see Science Selections, p. A34

DNA Adducts in Thai Industrial Estate Workers and Residents

The Map Ta Phut Industrial Estate (MIE) in Thailand is the site of the largest steel, oil refinery, and petrochemical factory complexes in Southeast Asia. Peluso et al. (p. 55) report on a cross-sectional study comparing levels of malondialdehyde-deoxyguanosine adducts (a biomarker of oxidative stress and lipid peroxidation) in peripheral blood lymphocyte DNA collected from 67 MIE workers, 58 Map Ta Phut residents, and 48 residents of a control district without proximity to industrial sources. The highest adduct levels were observed in steel factory workers, and adduct levels were significantly elevated in MIE workers and nearby residents relative to levels measured in control district residents, consistent with adverse effects of exposure to air pollution emitted from MIE complexes. The authors conclude that their findings substantiate the need for measures to reduce air pollution exposures among MIE workers and Map Ta Phut residents.

Organocholorine Pesticides and Breast and Prostate Cancers

Organochlorine (OC) pesticides have been inconsistently associated with hormone-related cancers, including cancers of the breast and prostate. Xu et al. (p. 60) conducted a cross-sectional study of serum levels of six OC pesticides and self-reported breast cancer (n = 63) or prostate cancer (n = 65) among 4,237 adult participants in the National Health and Nutrition Examination Surveys (1999-2004). The authors report that participants with increasing serum concentrations of [beta]-hexachlorocyclohexane (HCH), trans-nonachlor, and dieldrin were more likely to report a history of prostate cancer than participants with OC concentrations below the limits of detection, based on covariate-adjusted odds ratios. However, breast cancer was not associated with serum concentrations of any of the measured OC pesticides. The authors conclude that findings support an effect of OC pesticides on prostate cancer, but note that associations need to be confirmed in other populations.

Effects of Endocrine-Disrupting Chemicals on Human Dendritic Cells

Exposure to environmental endocrine-disrupting chemicals (EDCs) has been associated with dysregulated immune homeostasis, but potential effects on dendritic cells--which play a critical role in innate and adaptive immune responses--have not been investigated. Hung et al. (p. 67) studied effects of two common EDCs, nonylphenol (NP) and 4-octylphenol (4-OP), on cultured human myeloid dendritic cells (mDCs). …