China study finds associations between PM2.5 constituents and blood inflammation and coagulation

China study finds associations between PM2.5 constituents and blood inflammation and coagulation

30 June 2017

In a new study, a team from China has investigated the effects of various constituents of fine particulate matter (PM2.5) on blood inflammation and coagulation. The researchers found robust associations of the constituents—organic carbon (OC), elemental carbon (EC), nitrate (NO3), and ammonium (NH4+)—with at least 1 of 8 inflammatory markers.

On average, an interquartile range increase in the four PM constituents corresponded to increments of 50%, 37%, 25%, and 26% in inflammatory biomarkers, respectively. Only sulfate (SO42–) or NH4+ was robustly associated with coagulation markers (corresponding increments: 23% and 20%). A paper on their work is published in the ACS journal Environmental Science & Technology.

Associations between short-term exposure to fine particulate matter (PM2.5) and cardiovascular diseases (CVDs) have been well documented worldwide. PM2.5 has very complex chemical compositions and it was thus crucial to determine which constituents dominate the effects of PM2.5 on the cardiovascular system. However, investigations of the cardiovascular effects of specific constituents are scarce and limited to a small fraction of constituents, especially in developing countries.

An increasing number of studies have attempted to elucidate the time courses during which PM2.5 exposure causes adverse cardiovascular outcomes. … As the largest developing country in the world, China is facing enormous public health challenges due to severe air pollution problems and the heavy burden of CVDs. We therefore designed this longitudinal study in Shanghai, China, to explore the short-term associations of PM2.5 constituents on blood inflammation and coagulation, and further, to deduce which constituents are most deleterious to the cardiovascular system. Elderly patients with chronic obstructive pulmonary disease (COPD) were selected because they are hypothesized to be susceptible to the adverse cardiovascular effects of air pollutants as they have a higher deposition of particles and an inherent
inflammatory state.

—Liu et al.

The research team examined the associations between 10 constituents and 10 circulating biomarkers in a panel of 28 urban residents with 4 repeated measurements in Shanghai.

During the study period 27 May to 5 July 2014), the researchers obtained real-time
(hourly) concentrations of PM2.5 and its constituents from a fixed-site monitor located on the rooftop of a 5-story building.

They linked environmental and health data by the time of blood sampling. All biomarker measurements were natural log-transformed to improve the normality before statistical analyses. They incorporated several covariates as fixed-effect
terms in the analysis: (1) an indicator variable of “week” of blood collections to exclude any unknown weekly time trends; (2) an indicator variable of “day of the week” to control for the potential day-of-week effects; (3) the moving average of mean temperature and relative humidity on the current day and previous 3 days to
adjust for the confounding effects of weather conditions; and (4) individual characteristics, such as age, gender, body mass index, education, and the
152 history of morbidities. A random intercept was introduced to account for the within-subject correlations due to repeated measurements.

We found significant associations between PM2.5 and all cytokines, and these associations were restricted within 24 hours. We further identified some constituents, including OC, EC, SO42, NO3, and NH4+, have more robust associations with blood inflammation or coagulation than the remaining 5 constituents. Our findings were generally insensitive to the adjustment for gaseous pollutants.

—Liu et al.

Resources

  • Cong Liu, Jing Cai, Liping Qiao, Hongli Wang, Wenxi Xu, Huichu Li, Zhuohui Zhao, Renjie Chen, and Haidong Kan (2017) “The Acute Effects of Fine Particulate Matter Constituents on Blood Inflammation and Coagulation” Environmental Science & Technology doi: 10.1021/acs.est.7b00312

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