Threshold Limit Values: Historical Perspectives and Current Practice

• Published in: Journal of occupational and environmental medicine 1989-11, Vol.31 (11), p.910-918
• Main Authors: Ziem, Grace E., Castleman, Barry I.
• Format: Article
• Language: English
• Subjects: Air Pollutants, Occupational - adverse effects; Air Pollutants, Occupational - toxicity; Animals; Biological and medical sciences; Environmental Exposure; General aspects. Methods; Humans; Maximum Allowable Concentration; Medical sciences; National Institutes of Health (U.S.); Occupational Medicine; ORIGINAL ARTICLES; Toxicology; United States; United States Occupational Safety and Health Administration
• ISSN: 0096-1736; 1076-2752; 2332-3795
• DOI: 10.1097/00043764-198911000-00014

A 1989 Occupational Safety and Health Administration standard mandates that workplace air concentrations be held below new permissible exposure limits for 376 substances. As more than 350 of these limits came from the 1987 list of "Threshold Limit Values" (TLVs), the medical basis of the TLVs is of direct importance to the health of millions of workers. However, the TLV development process has been gravely flawed by lack of scientific rigor, inadequate medical input, and lack of attention to financial conflicts of interest. The adoption by the Occupational Safety and Health Administration of many poorly supported values as permissible exposure limits reflects also the underutilization of industrial medicine in identifying health effects of exposures below the TLVs. It is thus the responsibility of the medical profession to act on the presumption that the TLV permissible exposure limits are unsafe limits until a sound underlying body of medical and scientific literature exists for the substances on the list. It is industry's responsibility to commit itself seriously to medical and exposure monitoring and to begin to remedy the knowledge deficit that exists about the less immediate health effects of most industrial materials.