Associations between urinary biomarkers of oxidative stress and air pollutants observed in a randomized crossover exposure to steel mill emissions.

The effects of industrial air pollution on human health have not been as thoroughly investigated as those of urban air pollution which originates mostly from automotive transport. To better assess the health impacts of point sources of industrial air pollution, a randomized crossover exposure study was conducted. Sixty one young and healthy volunteers were randomly assigned to spend five consecutive eight-hour days near a steel mill or at a location five kilometres away. After a nine or sixteen-day washout period, volunteers spent another five consecutive days at the second site. Meteorological conditions and air pollutants were monitored at both exposure sites. On each exposure day, the first morning urine was collected along with a second urine sample obtained immediately before leaving the exposure site at the end of the day. Urinary levels of biomarkers of oxidative stress 8-hydroxy-2'-deoxyguanosine (8-OHdG, a biomarker of oxidative DNA damage), malondialdehyde (MDA, a biomarker of lipid peroxidation), 8-isoprostane (8-IsoP, a bioactive metabolite resulting from the peroxidation of arachidonic acid) and Vascular Endothelial Growth Factor (VEGF, involved in response to oxidative stress) were measured. According to mixed-effects linear regression models, intra-individual variations in 8-OHdG urinary levels were significantly associated with exposure site, but surprisingly, lower levels were observed at the steel mill site. Delayed, temporally-defined associations with specific air pollutants were observed for 8-OHdG, 8-IsoP and VEGF. However, these associations were subtle, presented complex patterns and their biological consequences remain unclear.

Exposure to air pollution near a steel plant and effects on cardiovascular physiology: a randomized crossover study.

BACKGROUND: Iron and steel industry is an important source of air pollution emissions. Few studies have investigated cardiovascular effects of air pollutants emitted from steel plants. OBJECTIVE: We examined the influence of outdoor air pollution in the vicinity of a steel plant on cardiovascular physiology in Sault Ste. Marie, Canada. METHODS: Sixty-one healthy, non-smoking subjects (females/males=33/28, median age 22 years) spent 5 consecutive 8-hour days outdoors in a residential area neighbouring a steel plant, or on a college campus approximately 5 kilometres away from the plant, and then crossed over to the other site with a 9-day washout. Mid day, subjects underwent daily 30-minute moderate intensity exercise. Blood pressure (BP) and pulse rate were determined daily and post exercise at both sites. Flow-mediated vasodilation (FMD) was determined at the site near the plant. Air pollution was monitored at both sites. Mixed-effects regressions were run for statistical associations, adjusting for weather variables. RESULTS: Concentrations of ultrafine particles, sulphur dioxide (SO2), nitrogen dioxide (NO2) and carbon monoxide (CO) were 50-100% higher at the site near the plant than at the college site, with minor differences in temperature, humidity, and concentrations of particulate matter ≤2.5 µm in size (PM2.5) and ozone (O3). Resting pulse rate [mean (95% confidence interval)] was moderately higher near the steel plant [+1.53 bpm (0.31, 2.78)] than at the college site, male subjects having the highest pulse rate elevation [+2.77 bpm (0.78, 4.76)]. Resting systolic and diastolic BP and pulse pressure, and post-exercise BP and pulse rate were not significantly different between two sites. Interquartile range concentrations of SO2 (2.9 ppb), NO2 (5.0 ppb) and CO (0.2 ppm) were associated with increased pulse rate [0.19 bpm (-0.00, 0.38), 0.86 bpm (0.03, 1.68), and 0.11 bpm (0.00, 0.22), respectively], ultrafine particles (10,256 count/cm(3)) associated with increased pulse pressure [0.85 mmHg (0.23, 1.48)], and NO2 and CO inversely associated with FMD [-0.14% (-0.31, 0.02), -0.02% (-0.03, -0.00), respectively]. SO2 during exercise was associated with increased pulse rate [0.26 bpm (0.01, 0.51)]. CONCLUSION: Air quality in residential areas near steel plants may influence cardiovascular physiology.

Acute changes in lung function associated with proximity to a steel plant: a randomized study.

BACKGROUND: Steel production is a major industry worldwide yet there is relatively little information on the pulmonary effects of air quality near steel manufacturing plants. OBJECTIVES: The aim of this study was to examine how lung function changes acutely when healthy subjects are situated near a steel plant which is adjacent to a residential area. METHODS: Sixty-one subjects were randomly assigned to spend 5 consecutive, 8-hour days in a residential neighborhood approximately 0.9km from a steel plant, or approximately 4.5km away at a college campus. Subjects crossed-over between sites after a nine-day washout period. Lung function was measured daily at both sites along with air pollutants including SO2, NO2, O3, PM2.5, and ultrafine particles. Diffusion capacity and pulse oximetry were also examined. RESULTS: Compared with the college site, the forced expiratory volume in 1-second/forced vital capacity, forced expiratory flow between 25% and 75% of the FVC, total lung capacity, functional residual capacity, and residual volume were lower near the steel plant by 0.67% (95% CI: 0.28, 1.06),1.62% (95% CI: 0.50, 2.75), 1.54% (95% CI: 0.68, 2.39), 3.54% (95% CI: 1.95, 5.13) and 11.3% (95% CI: 4.92, 17.75), respectively. Diffusion capacity, forced expiratory volume in 1s, and pulse oximetry were also lower near the plant but these effects were not statistically significant. Sulfur dioxide, ultrafine particulates, and oxides of nitrogen were greater near the steel plant site compared to the college site. CONCLUSIONS: Spending short periods of time near a steel plant is associated with a decrease in lung function.