Airborne particulate matter exposure in male sugarcane workers at risk for chronic kidney disease in Guatemala.

Background: There is an international epidemic of chronic kidney disease of unknown cause (CKDu) in agricultural working populations. Particulate air pollution is a likely contributing factor in populations at risk for CKDu, but there is little personal breathing zone data for these workers.

Methods: We collected 1 to 3 personal breathing zone particulate matter <5 microns (PM5) gravimetric measurements in 143 male sugarcane harvesters over 2 seasons and concurrent ambient samples using personal sampling pumps and cyclone inlets as a sampling train. Due to very high concentrations observed during a pilot of these methods, personal breathing zone sampling duration was set to 4 h, beginning either at the start of a work shift (AM) or delayed for 4 h (PM). To obtain full-shift exposure concentrations we calculated 8-h time-weighted average (TWA, in µg/m3) estimates of each worker's full-shift personal breathing zone PM5 exposure concentration by averaging their individual monitored concentration with the median concentration of the unmonitored AM or PM segment from all workers that day to obtain an 8-h TWA.

Results: Median full-shift personal TWA PM5 concentrations were 449 μg/m3 (range 20.5 to 1,930 μg/m3), which were much higher than ambient concentrations in these fields (median 136, range 22.5 to 2,360 μg/m3). These findings document very high personal breathing zone PM5 exposure in workers at risk for CKDu: median concentrations for all workers were 3.5 (range <1 to 33.6) times as high as concurrent ambient concentrations.

Significance: These findings suggest that ambient measurements of particulate matter are insufficient to estimate personal exposure in this population and that personal breathing zone monitoring should be used to fully explore air pollution as a risk factor for CKDu. Given that particulate matter from this source likely has multiple hazardous constituents, future research should focus on characterizing all constituents and explore associations with biomarkers of kidney injury.