Letters to the Editor
To the Editor:
We thank Dr Cherrie for his review for our article and the raised issues. Our study focused on the relations of urinary metabolites to inhalation and dermal exposure in shipyard spray painters. Dr Cherrie broadens the concern to another issue: the “biologically relevant” dermal exposure sampler.1
Although the dermal exposure is overestimated using the charcoal pads, the measurements of biomonitoring provide information about the total dose from inhalation and dermal exposure. In this study, results showed a significant relation between dermal exposure to xylene and urinary methylhippuric acid (MHA) levels adjusting for air xylene exposure. Meanwhile, dermal exposure to solvents is an important route. Berger-Preiss et al.2 recently indicated that dermal route contributes substantially to the total exposure of workers. In their study, the dose rates obtained for potential dermal exposure were higher than for inhalation exposure after use of biocides with low-pressure equipment indoors.
Dr Cherrie indicated that the sources of urinary metabolites may be the result of the inhalation exposure (average 1.2 ppm) and the dermal exposure contributed the equivalent of 2 to 3 ppm of inhaled vapor for xylene in the painters. However, the dose of dermal exposure was higher than that of inhalation exposure; dermal exposure to solvents is a major route. We have previously inferred that the average contribution of dermal absorption for the total exposure dose of xylene was 64%.3 The inhalation exposure levels were decreased as a result of wearing respirators and dermal exposure became the main route to the total burden of solvents.
We have conducted a study to determine the field effectiveness of protective suits and gloves by biomonitoring.4 Fifteen spray workers wore no protective clothing during the first week and wore protective suites and gloves during the second week. Both mandelic acid (MA) and MHA concentrations in the second week when spray painters wore protective suits and gloves were lower than in the first week, respectively. Mean decrease in MA and MHA biomarkers were 69% and 49%, respectively. According to the serial studies, there is convincing evidence that dermal absorption of solvents as a major exposure source among shipyard spray painters with respirators.
Fu-Kuei Chang, PhD
Mei-Lien Chen, PhD
Shu-Fang Cheng, PhD
Tung-Sheng Shih, PhD
I-Fang Mao, PhD
Chung Shan Medical University Taichung City, Taiwan
1. Lindsay FE, Semple S, Robertson A, Cherrie JW. Development of a biologically relevant dermal sampler. Ann Occup Hyg
2. Chang FK, Chen ML, Cheng SF, Shih TS, Mao IF. Evaluation of dermal absorption and protective effectiveness of respirators for xylene in spray painters. Int Arch Occup Environ Health.
2007;81:145–150. Epub 2007 May 10.
3. Berger-Preiss E, Boehncke A, Könnecker G, et al. Inhalational and dermal exposures during spray application of biocides. Int J Hyg Environ Health
4. Chang FK, Chen ML, Cheng SF, Shih TS, Mao IF. Field protection effectiveness of chemical protective suits and gloves evaluated by biomonitoring. Occup Environ Med.
2007;64:759–762. Epub 2007 May 23.
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