This is an effort to confirm changes biological monitoring according to changes in levels of exposure to styrene for industrial workers. This study was conducted on 108 workers, including male of 46 and female 44 who were working at factories of FRP, dipping, and coating. An improved passive monitor method(organic vapor monitor; OVM) was employed to determine levels of exposure. The biological monitoring include blood styrene concentration, urinary mandelic acid(MA), and urinary phenylglyoxylic acid(PGA). Biological monitoring were made through the collection of blood and urine.
The mean value of exposure to styrene was 21.0ppm, which is measured by organic vapor monitor, one of improved passive monitors. The highest exposure level was observed among workers in boat factories, laminating procedure workers, processing workers, respectively(p$lt;0.01). For exposure level, 11% of subjects under study showed over 50ppm which is timer weighted average(TWA).
The correlation coefficient between biological specimens and the exposure level was 0.62 for blood styrene concentration, 0.58 for MA corrected by creatinine, and 0.70 for PGA corrected by creatinine, respectively(p$lt;0.01). The regression analyses found exposure level relative importance in explaining variance in biological monitoring, In additional to that, gender was a significant factor in explaining variance of MA and MA+PGA. Almost half of variance(49%) in blood styrene concentration was explained by predictor,. including exposure level, age, gender, duration, and drinking volume during the last week (p$lt;0.01).
The very high correlations(higher than 0.9) was found when a comparison was made among three types of corrected methods, including uncorrected specific gravity and creatinine.
In conclusion, these findings suggest OVM to represent levels of exposure to styrene for industrial workers. A discussion was made on possible use of specific gravity sample for biological monitoring. Exposure level may be predicted an MA, PGA in urine, which could be applied to represent biological monitoring.
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