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.