Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
8551015 | Regulatory Toxicology and Pharmacology | 2018 | 8 Pages |
Abstract
In 2016, the American Conference of Governmental Industrial Hygienists (ACGIH) lowered the 8-hr Threshold Limit Value - time-weighted average (TLV-TWA) for toluene diisocyanate (TDI) from 5â¯ppb to 1â¯ppb, and the 15-min short-term exposure limit (STEL) from 20â¯ppb to 5â¯ppb. We evaluated ACGIH's basis for lowering these values. It is our opinion that the ACGIH's evaluation of the evidence for occupational asthma and respiratory effects from TDI exposure does not fully integrate the results of all the available human and animal studies. We found that some studies reported occupational asthma cases at TWAs less than 5â¯ppb, but these cases were likely caused by peak exposures above 20â¯ppb. Advances in industrial hygiene have reduced peak exposures and the incidence of upset conditions, such as spills and accidents, in modern TDI facilities. Taken together, the human evidence indicates that adherence to the previous 8-hr TLV-TWA and 15-min STEL (5â¯ppb and 20â¯ppb, respectively) prevents most, if not all, cases of occupational asthma, and eliminates or reduces the risk of lung function decrements and other respiratory effects. While limited, the animal literature supports the human evidence and indicates that TDI-induced asthma is a threshold phenomenon. We conclude that ACGIH's decision to lower the TLV-TWA and STEL values for TDI is not adequately supported.
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Authors
Heather N. Lynch, Robyn L. Prueitt, Julie E. Goodman,