Airborne particulate matter and mitochondrial damage: a cross-sectional study.
Oxidative stress generation is a primary mechanism mediating the effects of Particulate Matter (PM) on human health. Although mitochondria are both the major intracellular source and target of oxidative stress, the effect of PM on mitochondria has never been evaluated in exposed individuals.


METHODS
In 63 male healthy steel workers from Brescia, Italy, studied between April and May 2006, we evaluated whether exposure to PM was associated with increased mitochondrial DNA copy number (MtDNAcn), an established marker of mitochondria damage and malfunctioning. Relative MtDNAcn (RMtDNAcn) was determined by real-time PCR in blood DNA obtained on the 1st (time 1) and 4th day (time 2) of the same work week. Individual exposures to PM10, PM1, coarse particles (PM10-PM1) and airborne metal components of PM10 (chromium, lead, arsenic, nickel, manganese) were estimated based on measurements in the 11 work areas and time spent by the study subjects in each area.


RESULTS
RMtDNAcn was higher on the 4th day (mean = 1.31; 95%CI = 1.22 to 1.40) than on the 1st day of the work week (mean = 1.09; 95%CI = 1.00 to 1.17). PM exposure was positively associated with RMtDNAcn on either the 4th (PM10: beta = 0.06, 95%CI = -0.06 to 0.17; PM1: beta = 0.08, 95%CI = -0.08 to 0.23; coarse: beta = 0.06, 95%CI = -0.06 to 0.17) or the 1st day (PM10: beta = 0.18, 95%CI = 0.09 to 0.26; PM1: beta = 0.23, 95%CI = 0.11 to 0.35; coarse: beta = 0.17, 95%CI = 0.09 to 0.26). Metal concentrations were not associated with RMtDNAcn.


CONCLUSIONS
PM exposure is associated with damaged mitochondria, as reflected in increased MtDNAcn. Damaged mitochondria may intensify oxidative-stress production and effects.
Hou
Lifang
L
Department of Preventive Medicine, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA. l-hou@northwestern.edu
Zhu
Zhong-Zheng
ZZ
Zhang
Xiao
X
Nordio
Francesco
F
Bonzini
Matteo
M
Schwartz
Joel
J
Hoxha
Mirjam
M
Dioni
Laura
L
Marinelli
Barbara
B
Pegoraro
Valeria
V
Apostoli
Pietro
P
Bertazzi
Pier Alberto
PA
Baccarelli
Andrea
A
D000393:Air Pollutants / Q000009:adverse effects* / Q000032:analysis; D003430:Cross-Sectional Studies; D004249:DNA Damage; D004272:DNA, Mitochondrial / Q000187:drug effects*; D006801:Humans; D007558:Italy; D008297:Male; D008928:Mitochondria / Q000187:drug effects*; D016273:Occupational Exposure; D018384:Oxidative Stress / Q000187:drug effects; D052638:Particulate Matter
D000393:Air Pollutants; D004272:DNA, Mitochondrial; D052638:Particulate Matter