Published ahead of print on May 8, 2008, doi:10.1164/rccm.200708-1286OC Am. J. Respir. Crit. Care Med., Volume 178, Number 3, August 2008, 283-289 A more recent version of this article appeared on August 1, 2008
Submitted on August 30, 2007 Traffic-Related Particles are Associated with Elevated Homocysteine: the VA Normative Aging StudySung Kyun Park1*,1 Department of Environmental Health Sciences, University of Michigan School of Public Health, Ann Arbor, MI, USA, 2 Department of Environmental Health Sciences, University of Michigan School of Public Health, Ann Arbor, MI, USA; Department of Epidemiology, University of Michigan School of Public Health, Ann Arbor, MI, USA, 3 VA Normative Aging Study, Veterans Affairs Boston Healthcare System, Boston, MA, USA; School of Medicine, Boston University, Boston, MA, USA; School of Public Health, Boston University, Boston, MA, USA, 4 VA Normative Aging Study, Veterans Affairs Boston Healthcare System, Boston, MA, USA; School of Public Health, Boston University, Boston, MA, USA, 5 Jean Mayer US Department of Agriculture Human Nutrition Research Center on Aging, Tufts University, Boston, MA, USA, 6 Department of Environmental Health, Harvard School of Public Health, Boston, MA, USA, 7 Department of Environmental Health Sciences, University of Michigan School of Public Health, Ann Arbor, MI, USA; Department of Epidemiology, University of Michigan School of Public Health, Ann Arbor, MI, USA; Department of Environmental Health, Harvard School of Public Health, Boston, MA, USA * To whom correspondence should be addressed. E-mail: sungkyun{at}umich.edu.
Rationale: Recent epidemiologic studies have shown that homocysteine, a sulfur-containing amino acid formed during the metabolism of methionine, is a risk factor of atherosclerosis, myocardial infarction, stroke, and thrombosis. Particulate air pollution has been related to cardiovascular death and hospital admission, but the underlying mechanisms are not fully elucidated. Objectives: We examined the associations between ambient particulate air pollution and plasma concentrations of homocysteine among 960 community-residing older men (mean age 73.5 ± 6.9 years). Methods: Total homocysteine in plasma, measured using high-performance liquid chromatography with fluorescence detection, was regressed on each ambient particulate pollutant (black carbon, organic carbon, sulfate or PM2.5), and effect modification by plasma and dietary B-vitamins (folate, B6 and B12) was examined. Main Results: The median concentration of total homocysteine was 10.1 µmol/L. Statistically significant positive associations of total homocysteine were observed with traffic-related particles (black carbon and organic carbon). No association was observed with sulfate, an indicator of coal combustion particles, or PM2.5. The effects of black carbon and organic carbon were more pronounced in persons with low concentrations of plasma folate and vitamin B12. Conclusion: Exposures to ambient particles, particularly from traffic, are associated with elevated plasma total homocysteine. Homocysteine may be a component or biological marker of the oxidation pathways underlying the effect of ambient particles on the cardiovascular system. Key words: air pollution, folate, homocysteine, traffic particles, vitamin B12
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