An Evaluation of the Relationship among Urine, Air, and Hand Measures of Exposure to Bisphenol A (BPA) in US Manufacturing Workers

Abstract

Background

Exposure to bisphenol A (BPA) can be assessed using external and internal exposure measures. We examined the relationship between two measures of external BPA exposure (air and hand-wipe samples) and one of internal exposure (total BPA in urine) for a group of US manufacturing workers.

Methods

During 2013–2014, we recruited 78 workers from six US companies that made BPA or made products with BPA. We quantified BPA in seven urine samples, two full-shift air samples and in pre- and end-shift hand-wipe samples collected from workers over 2 consecutive days. We examined correlations between creatinine-corrected urinary concentrations of total BPA (total BPA_CR) and BPA levels in air and hand wipes using Pearson's correlation coefficient. We also applied mixed-effects regression models to examine the relationship between total BPA_CR with BPA in air (urine~air model) and with BPA in end-shift hand wipes (urine~hand model), separately and together (urine~air+hand model), after adjusting for covariates.

Results

End-shift total BPA_CR strongly correlated with BPA in air (r_p = 0.79, P < 0.0001) and nearly as strongly with BPA in end-shift hand wipes (r_p = 0.75, P < 0.0001). In mixed-effect models, BPA air concentration and end-shift hand-wipe BPA level were significantly and positively associated with end-shift total BPA_CR (P < 0.0001 each). We found a significant effect of the Day 1 BPA air concentration on Day 2 total BPA_CR (P = 0.0104). When BPA air concentration and end-shift hand-wipe BPA level were in the same model, the air concentration (P < 0.0001) was more significant than the hand-wipe level (P = 0.0106).

Conclusion

BPA levels in air and end-shift hand wipes strongly correlated with total BPA_CR, suggesting that both inhalation and dermal contract were likely exposure routes; however, inhalation, on average, appeared to be a more dominant exposure route than dermal contact for these manufacturing workers.