Department of Industrial Hygiene and Toxicology, Institute of Occupational Health, Helsinki, Finland.
Scand J Work Environ Health. 1979 Sep;5(3):217-31. doi: 10.5271/sjweh.3096.
Sedentary volunteer subjects were exposed to an m-xylene concentration of about 3.9 mmol/m3 over five successive days, 6 h/d. It was noted that about 60% of the inhaled xylene was retained in the lungs. The estimated daily uptake of xylene was recovered nearly quantitatively as methylhippuric acid in the urine. Other pathways of xylene excretion played a minor role. The rate of 2,4-xylenol excretion shortly after a day's exposure was about 1-2% of that for methylhippuric acid excretion, and pulmonary excretion of unchanged xylene amounted to about 4% of the estimated uptake. In the blood, xylene was mainly associated with serum proteins, and only small amounts resided in the cells. Postexposure excretion of xylene in expired air and the urinary excretion of methylhippuric acid were initially rapid (elimination half-time about 1 h), and after an intermediate phase it attained, some 6-16 h after the exposure, a slow phase of elimination (half-time about 20 h). These observations are congruent with the concept that xylene is distributed to at least two main tissue compartments in the body. The slow elimination takes place from tissues with a high xylene solubility and a small perfusion, for example, adipose tissue; in this compartment cumulation of xylene occurs over repeated exposures. Under the conditions studied no signs of saturation of the metabolic pathways or renal excretion were noted.
志愿者在连续五天内，每天暴露于 m-二甲苯浓度约为 3.9mmol/m3 的环境中，每天 6 小时。据观察，约 60%的吸入二甲苯被保留在肺部。尿液中甲基马尿酸几乎定量地回收了二甲苯的估计日摄入量。其他二甲苯排泄途径作用较小。一天暴露后不久，2,4-二甲酚的排泄速度约为甲基马尿酸排泄速度的 1-2%，未变化的二甲苯通过肺部排泄量约占估计吸收量的 4%。在血液中，二甲苯主要与血清蛋白结合，只有少量存在于细胞中。暴露后二甲苯在呼出空气中的排泄和甲基马尿酸在尿中的排泄最初很快（消除半衰期约为 1 小时），在中间阶段之后，约在暴露后 6-16 小时，达到缓慢的消除阶段（半衰期约为 20 小时）。这些观察结果与二甲苯分布于体内至少两个主要组织隔室的概念一致。缓慢的消除发生在二甲苯溶解度高且灌注少的组织中，例如脂肪组织；在这个隔室中，二甲苯会在重复暴露中积累。在研究条件下，未观察到代谢途径或肾脏排泄的饱和迹象。
