Environmental monitoring of occupational exposure to N,N-dimethylformamide: comparison between active and diffusive sampling

Abstract

The objective of this study is to optimize the evaluation of the exposure to N,N-dimethylformamide (DMF) in synthetic leather factories by diffusive samplers. The DMF exposure was monitored in synthetic leather factories by two sampler types: active and diffusive. Air measurements were carried out using two different personal air samplers, a diffusive and an active one. The diffusive sampling method, TK200 with charcoal filters, was examined in comparison with pumping through NIOSH silica gel tubes workplace air as with the currently available "gold standard". The evaluation was carried out, in two different years but in the same season, for all the duration of the shift, i.e. 8 h on workers employed in five different factories in the district of Florence and Prato (Italy). The statistical and graphical analysis of data show a good correlation between active and passive samplers (r = 0.96, P < 0.001, n = 91), a good linear regression (DMF(diffusive )= 0.95 DMF(active) + 0.15, R (2) = 0.92), a not statistically significant difference between data (tested by paired t test and non-parametric Wilcoxon test). Moreover, all these results are confirmed for data lower and higher than TLV-TWA, in particular we found a significant Pearson correlation (r = 0.92, P < 0.001, n = 83; r = 0.92, P < 0.05, n = 8, respectively) and a significant linear regression (DMF(diffusive )= 0.88 DMF(active) + 0.73, R (2 )= 0.86; DMF(diffusive )= 0.90 DMF(active) + 3.76, R (2 )= 0.85). Besides, the analysis of graphical representations confirmed the previous evidences. Finally, we can not find a significant difference between different types of job. Due to the good agreement between the two groups of data, the TK200 samplers can be considered as a simpler approach than the pump for screening worker exposures to DMF.