Sauvé Jean-François, Lévesque Martine, Huard Mélanie, Drolet Daniel, Lavoué Jérôme, Tardif Robert, Truchon Ginette
a Department of Environmental and Occupational Health , Université de Montréal , Montréal , Québec , Canada.
J Occup Environ Hyg. 2015;12(2):123-9. doi: 10.1080/15459624.2014.955179.
Reference values for the biological monitoring of occupational exposures are generally normalized on the basis of creatinine (CR) concentration or specific gravity (SG) to account for fluctuations in urine dilution. For instance, the American Conference of Governmental Industrial Hygienists (ACGIH(®)) uses a reference value of 1g/L for CR. The comparison of urinary concentrations of biomarkers between studies requires the adjustment of results based on a reference CR and/or SG value, although studies have suggested that age, sex, muscle mass, and time of the day can exert non-negligible influences on CR excretion, while SG appears to be less affected. The objective of this study was to propose reference values for urinary CR and SG based on the results of samples sent for analysis by occupational health practitioners to the laboratory of the Occupational Health and Safety Research Institute of Québec (IRSST). We analyzed a database containing 20,395 urinary sample results collected between 1985 and 2010. Linear mixed-effects models with worker as a random effect were used to estimate the influence of sex and collection period on urinary CR and SG. Median CR concentrations were 25-30% higher in men (1.6 g/L or 14.4 mmol/L) than in women (1.2 g/L or 10.2 mmol/L). Four percent of the samples for men and 12% for women were below the acceptable threshold for CR (4.4 mmol/L). For SG, 5% of samples for men and 12% for women were below the threshold of 1.010. The difference in SG levels between sexes was lower than for CR, with a median of 1.024 for men compared to 1.020 for women. Our results suggest that the normalization of reference values based on a standard CR value of 1 g/L as proposed by the ACGIH is a conservative approach. According to the literature, CR excretion is more influenced by physiological parameters than SG. We therefore suggest that correction based on SG should be favored in future studies involving the proposal of reference values for the biological monitoring of occupational exposures.
职业接触生物监测的参考值通常根据肌酐（CR）浓度或比重（SG）进行标准化，以考虑尿液稀释的波动。例如，美国政府工业卫生学家会议（ACGIH(®)）使用的CR参考值为1g/L。尽管研究表明年龄、性别、肌肉质量和一天中的时间对CR排泄有不可忽视的影响，而SG似乎受影响较小，但不同研究之间生物标志物尿浓度的比较需要根据参考CR和/或SG值对结果进行调整。本研究的目的是根据职业健康从业者送往魁北克职业健康与安全研究所（IRSST）实验室进行分析的样本结果，提出尿CR和SG的参考值。我们分析了一个包含1985年至2010年间收集的20395份尿样结果的数据库。以工人为随机效应的线性混合效应模型用于估计性别和采集期对尿CR和SG的影响。男性的CR浓度中位数（1.6g/L或14.4mmol/L）比女性（1.2g/L或10.2mmol/L）高25 - 30%。男性样本中有4%、女性样本中有12%低于CR的可接受阈值（4.4mmol/L）。对于SG，男性样本中有5%、女性样本中有12%低于1.010的阈值。性别之间SG水平的差异低于CR，男性中位数为1.024，女性为1.020。我们的结果表明，按照ACGIH提议的基于1g/L标准CR值对参考值进行标准化是一种保守的方法。根据文献，CR排泄比SG更容易受到生理参数的影响。因此，我们建议在未来涉及职业接触生物监测参考值提议的研究中，应优先基于SG进行校正。
