Mason H J, Hindell P, Williams N R
Health & Safety Laboratory, Sheffield, UK.
Occup Med (Lond). 2001 Feb;51(1):2-11. doi: 10.1093/occmed/51.1.2.
Occupational health professionals' interest in controlling mercury (Hg) exposure, and the use of biological monitoring in this context, has been ongoing for a number of years. Evidence from urinary Hg results in a number of UK firms who have undertaken some form of biological monitoring or occupational health surveillance suggest that exposure has decreased over the last 10-15 years. This decrease precedes the establishment in the UK of an advisory biological monitoring guidance value (HGV) for urinary Hg and the production of updated medical guidance from the Health & Safety Executive on Hg exposure (MS12 1996). This latter document recommends a urinary sampling interval for urinary Hg of between 1 and 3 months, which is consistent with the reported toxicokinetics of Hg excretion, but we highlight that urinary Hg represents integrated exposure over many previous months. Mercury is a recognized nephrotoxin and MS12 1996 mentions the use of regular dipstick protein estimations. We review our experience of investigating proteinuria and enzymuria in a large-scale cross-sectional occupational study. The incidence of Hg-induced renal disease is probably very rare at current exposure levels. Therefore acceptance of a high false-positive rate of proteinuria not related to Hg exposure needs to be considered in any urinary protein testing regime of Hg workers. The establishment of an HGV for urinary Hg has raised questions about the uncertainty associated with a urinary Hg result, including factors such as diurnal variation, whether urine correction by creatinine or specific gravity is preferable and the possibility of non-occupational sources of Hg contributing significantly towards breaching the HGV. Correction of urinary Hg results by creatinine or specific gravity and the use of a fixed sampling time, such as the beginning or end of the day, substantially reduce the uncertainty in a urinary Hg measurement. But even with good laboratory precision, an individual with a true urinary Hg excretion of 20 nmol/mmol creatinine could supply urine samples of between 14 and 26 nmol/mmol creatinine. The influence of dietary sources in the UK contributing to urinary Hg values approaching or exceeding the HGV is unlikely. The use of tribal or ethnic cosmetics and remedies needs to be considered if a urinary Hg result looks inappropriately high, as some such preparations have been found to contain Hg and can be absorbed through the skin. The ability of excessive chewers or teeth grinders who have a large number of dental amalgam fillings to breach the urinary HGV in the absence of substantial occupational Hg exposure has been reported in a few Scandanavian studies. We report here a likely case of this phenomenon. Since the establishment of the HGV, our biological monitoring Hg data from a number of industry sectors using inorganic or metallic Hg have suggested that a minority of samples (13%) are still greater than the HGV.
多年来,职业健康专业人员一直关注控制汞(Hg)暴露以及在此背景下生物监测的应用。来自英国一些进行了某种形式生物监测或职业健康监测的公司的尿汞结果表明,在过去10至15年中,汞暴露有所下降。这种下降早于英国建立尿汞的生物监测咨询指导值(HGV)以及健康与安全执行局发布关于汞暴露的最新医学指南(MS12 1996)。后一份文件建议尿汞的尿样采集间隔为1至3个月,这与报道的汞排泄毒代动力学一致,但我们强调尿汞代表了过去数月的综合暴露。汞是一种公认的肾毒素,MS12 1996提到了定期使用试纸条估计尿蛋白的方法。我们回顾了在一项大规模横断面职业研究中调查蛋白尿和酶尿的经验。在当前暴露水平下,汞诱导的肾脏疾病发病率可能非常低。因此,在任何汞作业工人的尿蛋白检测方案中,都需要考虑接受与汞暴露无关的蛋白尿高假阳性率。尿汞HGV的建立引发了关于尿汞结果不确定性的问题,包括诸如昼夜变化、用肌酐或比重校正尿液是否更可取以及非职业性汞源对突破HGV有显著贡献的可能性等因素。用肌酐或比重校正尿汞结果以及使用固定的采样时间,如一天的开始或结束时,可大幅降低尿汞测量的不确定性。但即使实验室精度良好,一个真正尿汞排泄量为20 nmol/mmol肌酐的个体提供的尿样肌酐含量可能在14至26 nmol/mmol之间。在英国,饮食来源对尿汞值接近或超过HGV的影响不太可能。如果尿汞结果看起来过高,需要考虑使用部落或民族化妆品及药物的情况,因为已发现一些此类制剂含有汞且可经皮肤吸收。一些斯堪的纳维亚研究报告称,在没有大量职业汞暴露的情况下,大量牙齿有汞合金填充物的过度咀嚼者或磨牙者有可能突破尿HGV。我们在此报告了一个可能的此类现象案例。自HGV建立以来,我们从多个使用无机或金属汞的行业部门获得的生物监测汞数据表明,少数样本(13%)仍高于HGV。