Airborne particulate matter exposure and urinary albumin excretion: the Multi-Ethnic Study of Atherosclerosis.
OBJECTIVE
Understanding mechanistic pathways linking airborne particle exposure to cardiovascular health is important for causal inference and setting environmental standards. We evaluated whether urinary albumin excretion, a subclinical marker of microvascular function which predicts cardiovascular events, was associated with ambient particle exposure.


METHODS
Urinary albumin and creatinine were measured among members of the Multi-Ethnic Study of Atherosclerosis at three visits during 2000-2004. Exposure to PM(2.5) and PM(10) (microg/m(3)) was estimated from ambient monitors for 1 month, 2 months and two decades before visit one. We regressed recent and chronic (20 year) particulate matter (PM) exposure on urinary albumin/creatinine ratio (UACR, mg/g) and microalbuminuria at first examination, controlling for age, race/ethnicity, sex, smoking, second-hand smoke exposure, body mass index and dietary protein (n = 3901). We also evaluated UACR changes and development of microalbuminuria between the first, and second and third visits which took place at 1.5- to 2-year intervals in relation to chronic PM exposure prior to baseline using mixed models.


RESULTS
Chronic and recent particle exposures were not associated with current UACR or microalbuminuria (per 10 microg/m(3) increment of chronic PM(10) exposure, mean difference in log UACR = -0.02 (95% CI -0.07 to 0.03) and relative probability of having microalbuminuria = 0.92 (95% CI 0.77 to 1.08)) We found only weak evidence that albuminuria was accelerated among those chronically exposed to particles: each 10 microg/m(3) increment in chronic PM(10) exposure was associated with a 1.14 relative probability of developing microalbuminuria over 3-4 years, although 95% confidence intervals included the null (95% CI 0.96 to 1.36).


CONCLUSIONS
UACR is not a strong mechanistic marker for the possible influence of air pollution on cardiovascular health in this sample.
O'Neill
M S
MS
University of Michigan School of Public Health, 6631 SPH Tower, 109 South Observatory, Ann Arbor, MI 48109-2029, USA. marieo@umich.edu
Diez-Roux
A V
AV
Auchincloss
A H
AH
Franklin
T G
TG
Jacobs
D R
DR
Astor
B C
BC
Dvonch
J T
JT
Kaufman
J
J
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000393:Air Pollutants / Q000633:toxicity; D000397:Air Pollution / Q000009:adverse effects / Q000706:statistics & numerical data*; D000419:Albuminuria / Q000453:epidemiology*; D002318:Cardiovascular Diseases / Q000208:ethnology / Q000209:etiology; D003404:Creatinine / Q000652:urine; D005260:Female; D006801:Humans; D019570:Inhalation Exposure / Q000009:adverse effects / Q000706:statistics & numerical data*; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D052638:Particulate Matter / Q000633:toxicity*; D044469:Racial Groups; D014481:United States / Q000453:epidemiology
D000393:Air Pollutants; D052638:Particulate Matter; D003404:Creatinine