Urinary metabolite levels in workers handling p-tert-butylphenol as an index of personal exposure.

Occupational exposure to p-tert-butylphenol (PTBP) was studied in a workplace where workers were engaged in packing this alkylphenol in bags or transporting the bags by fork-lift. The geometrical mean of eight-hour-time-weighted-average (8 h-TWA) value for personal ambient PTBP level of the packers was 0.39 mg/m3 (n = 15), higher than that of the carriers (0.10 mg/m3, n = 5). Amounts of PTBP collected in the respirators used by the workers were in proportion to the 8 h-TWA values but lower than the estimated theoretical amounts; considerable amounts of PTBP were assumed to be absorbed through the respiratory tract. The urine excreted during the latter half of the shift showed the highest levels of PTBP (geometrical mean: packer, 5.07 micrograms/ml, n = 20; carrier, 3.03 micrograms/ml, n = 8). When the workers were away from the workplace, PTBP levels decreased; most was excreted within 24 h. Correlation between the urinary PTBP levels and 8 h-TWA values was significant (r = 0.46, n = 19, P less than 0.05), but its extent was weak. The total amounts of urinary PTBP excreted for 24 h after the start of the shift were two to three times higher than the estimated respiratory absorption of PTBP; PTBP was assumed to be absorbed not only through the respiratory tract but also through intact skin. It was concluded that the personal ambient PTBP level is not a suitable index for personal exposure, and biological monitoring via the PTBP level in the urine excreted at the end of the each shift is useful for the evaluation of personal exposure.