對－二氯苯(1,4-Dichlorobenzene; p-DCB)是一種人工合成除臭劑，具有天然芳香味，在室溫易昇華。研究發現p-DCB之暴露途徑主要為呼吸暴露與皮膚接觸，但勞工暴露研究顯示作業環境空氣中p-DCB濃度為4.3±1.13ppm ，約為德國作業環境空氣中容許濃度之1/12（MAK：50ppm，300 mg/m3) ，但勞工尿中p-DCB代謝物之總2,5-DCP濃度 則為41.10±31.44 mg/g creatinine約為德國勞工生物偵測指標值（BAT 150 mg/g creatinine）之1/3~1/4，依比例計算尿中p-DCB代謝物濃度較空氣中p-DCB濃度高出四倍，因此皮膚暴露途徑不可排除。此外，目前p-DCB皮膚暴露資料與連續24小時暴露後體內濃度動力學之變化情形並沒有任何資料。因此，本研究之目的為進行驅蟲劑製造業勞工空氣及皮膚p-DCB之暴露評估。進一步探討p-DCB在連續暴露三天後尿中p-DCB與其代謝物是否會有累積現象，以及勞工停止暴露後，勞工24小時尿中2,5-DCP之動力學。
本研究選取16位驅蟲劑製造業勞工，分別採集分析連續三天作業環境空氣中p-DCB濃度、個人皮膚暴露濃度、上班前後尿中p-DCB及代謝物2,5-DCP濃度，並選擇八位勞工收集暴露結束24小時尿液進行生物偵測指標2,5-DCP動力學分析。
本研究結果發現，在連續三天作業環境空氣中氣狀p-DCB平均濃度呈現一致狀態（15.1±1.37 ppm），且未超過作業環境空氣中有害物容許濃度標準（75 ppm），但由於未進行固相p-DCB採樣分析，可能造成勞工個人暴露濃度低估。勞工個人皮膚暴露濃度分析結果（5.65±2.35 μg/cm2）顯示，在各部位皮膚暴露濃度高低上，以手心暴露之p-DCB濃度最高，頸部最低，高低順序為手心濃度＞手前臂內側＞手掌背＞額頭＞頸部，此結果與研究假設相符，顯示有皮膚暴露的可能性，且勞工各皮膚部位暴露濃度高低具一致性，然而，皮膚和空氣暴露未具相關性，可能與本研究中未進行空氣中固相p-DCB之採樣分析關。在暴露前後尿液中未經肌肝酸校正之p-DCB及2,5-DCP濃度差值之平均值及標準偏差分別為0.45±8.49及 1.75±3.65 μg/L，與空氣中p-DCB及2,5-DCP濃度不具相關性，但在暴露前後尿液中未經肌肝酸校正之p-DCB濃度差值與皮膚暴露濃度呈現正相關。因此，建議進行空氣和皮膚共同暴露p-DCB，應進一步探討在有皮膚暴露下，p-DCB之皮膚吸收效率才能進一步釐清二種暴露途徑之皮膚貢獻量。本研究尿中p-DCB或是2,5-DCP濃度累積部分，經由統計發現，尿中p-DCB並未出現顯著累積，此結果符合動物實驗數據，暴露後當天便會排出。此外，在尿中2,5-DCP部分，隨暴露天數遞增，尿中濃度2,5-DCP呈現上升的趨勢，且亦達顯著相關。在動力學部分，則發現在皮膚和空氣的共同暴露的情境下，尿中代謝物的半衰期約為4Hr，與實驗室經由呼吸暴露條件下所獲得半衰期31.5Hr不同。但因本研究之半衰期推估僅為一人之結果，其數據強度不足，建議應進行多人較長時間之測試。由基本人口資料中發現該類工廠勞工，在個人防護具使用率不高，基於暴露濃度高於TLV(恕限值)，且手部皮膚暴露量亦高，建議使用適當之呼吸及手部防護具。

para-dichlorobenzene (p-DCB) has been widely used as synthetic deodorant and moth repellent and could be easily sublimated in room temperature. The main exposure routes in occupational environment are by inhalation and skin. Previous finding in a survey in Taiwan showing the urinary levels of 2,5-DCP, biomarker of p-DCB, were only 1/3~1/4 of BAT（BAT 150 mg/g creatinine）with low ambient p-DCB concentrations (1/12 of MAK; MAK: 50 ppm), suggesting that the skin absorption could not be excluded. Moreover, limited studies reported the quantitative assessment in excretory kinetic parameters for occupational exposure to p-DCB. Furthermore, few studies were conducted for the exploration of the relations of p-DCB exposure to the exposure biomarker of 2,5-Dichlorophenol(2,5-DCP). Therefore, the aims of study are to explore the relationship between ambient and dermal exposure p-DCB concentrations. In addition, to explore whether the accumulation of the urinary 2,5-DCP existed or not, and to determine the metabolic kinetic parameters of urinary 2,5-DCP.
In this study, 16 p-DCB-exposed workers were selected to monitor their ambient p-DCB exposure levels, skins exposure dose, and urinary 2,5-DCP levels at both pre-shift and post-shift during 3 consecutive day. Eight p-DCB processing workers were chosen to monitor 24-hour urinary metabolites of p-DCB for set up the metabolic kinetic parameters.
In our results, the geometric mean and standard deviation of ambient p-DCB concentrations were 15.1±1.37 ppm, and all the measurements below the PEL. Due to the particle phase of ambient p-DCB were not monitored, the lower exposure levels of ambient p-DCB for workers may be estimate. The geometric mean and standard deviation of skin exposure levels of p-DCB were 5.65±2.35 μg/cm2 and the highest level was found in palm, neck was the lowest. The relationship between ambient and skin exposure levels was not inconsistent due to the particle phase of ambient p-DCB was not monitored in this study. The geometric mean and standard deviation of differential values of pre- and post urinary p-DCB and 2,5-DCP were 0.45±8.49及 1.75±3.65 μg/L respectively, and only showed significant correlation with skin exposure levels of p-DCB. According these data, we suggested the absorption rate of p-DCB should be verified when the concurrent exposure of ambient and skin exposure existed. Then, the contribution from skin exposure pathway could be estimated. The statistical data of three-days urinary p-DCB levels showed that the urinary p-DCB were not accumulated, but the urinary 2,5-DCP levels significantly raised with the sampling time. The half life of urinary 2,5-DCP was estimated as 4 hours, lower than the half life of 31.5 hours from human experimental study. Due to only one data set was made in this study, the representative and strength of the estimate should be improved in the future. According the walk-through records of the plant, the personal protective measures were suggested to effectively reduce the exposure of p-DCB.

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