Data from: Derivation of occupational thresholds of toxicological concern for airborne systemically-acting non-carcinogenic organic chemicals

Many substances in workplace do not have occupational exposure limits (OELs). The threshold of toxicological concern (TTC) principle is part of the hierarchy of approaches useful in occupational health risk assessment. The aim of this study was to derive occupational TTCs (OTTCs) reflecting the airborne concentrations below which no significant risk to workers would be anticipated. A reference dataset consisting of the 8-h threshold limit values -Time-Weighted Average (8-h TLV-TWA) for 280 organic substances was compiled. Each substance was classified into low (Class I), intermediate (Class II) or high (Class III) hazard categories as per Cramer rules. For each chemical, n-octanol:water partition coefficient and vapor pressure along with the molecular weight were used to predict the blood:air partition coefficient. The blood:air partition coefficient along with data on water solubility and ventilation rate allowed the prediction of pulmonary retention factor and absorbed dose in workers. For each Cramer class, the distribution of the predicted doses was analyzed to identify the various percentile values corresponding to occupational OTTC. Accordingly, for Cramer Classes I, II and III, the OTTCs derived in the present study correspond to 0.15, 0.0085 and 0.006 mmol/day at the 10th percentile level, while these values were 1.5, 0.09 and 0.03 mmol/day at the 25th percentile level. The proposed occupational TTCs are not meant to replace the traditional OELs, but can be used in data-poor situations along with exposure estimates to support screening level risk assessment and prioritization.

职场环境中的诸多物质尚未制定职业接触限值（occupational exposure limits, OELs）。毒理学关注阈值（threshold of toxicological concern, TTC）原则是职业健康风险评估常用方法体系中的组成部分。本研究旨在推导职业性毒理学关注阈值（occupational TTCs, OTTCs），即对应不会对劳动者造成显著健康风险的空气暴露浓度阈值。本研究编制了包含280种有机物质的8小时时间加权平均阈限值（8-h TLV-TWA）参考数据集。依据Cramer规则，将每种物质划分为低（I类）、中（II类）、高（III类）危害等级。针对每种化学物质，研究采用正辛醇-水分配系数、蒸气压与分子量，预测其血-空气分配系数。结合血-空气分配系数、水溶性及通风速率数据，可进一步推导劳动者的肺滞留因子与吸收剂量。针对每一类Cramer等级，研究通过分析预测剂量的分布特征，确定对应职业性毒理学关注阈值的各百分位数值。据此，在第10百分位水平下，Cramer I、II、III类对应的职业性毒理学关注阈值分别为0.15、0.0085和0.006 mmol/天；而在第25百分位水平下，对应数值则为1.5、0.09和0.03 mmol/天。本研究提出的职业性毒理学关注阈值并非旨在替代传统职业接触限值，而是可在缺乏实测数据的场景中，结合暴露估算结果，用于支持筛查级风险评估与优先级排序工作。