The origin and basis of threshold limit values

Abstract

The concept of establishing a "threshold limit" for contaminants of industrial air is based on the principles of establishing: (1) quantitative relationships between the magnitude and duration of exposure to an industrial substance and the nature and magnitude of the response of the worker, and (2) a limiting level of exposure to potentially hazardous agents, when there exists no significant threat to health. This paper focuses on the origin of this concept, and traces the history and development of thought concerning the founding principles upon which it is based. The TLVs have undergone a remarkable evolution, from values denoting concentrations of contaminant producing overt signs of acute toxicity, to those concentrations to which nearly all workers may be exposed for their working lifetime without experiencing adverse health effects.

Risk management—the Swedish way(s)

“…NBOSH, like most other national authorities in Europe, publish a new version of their list of exposure limits every 1-3 years. The national American authority, OSHA, has failed-in spite of repeated attempts-to update its values, due to the massive judicial process that follows every single change of an exposure limit (Hansson, 1998:18-20;Paull, 1984;Robinson et al, 1991;Paustenbach, 1997).…”

Uma visão crítica do uso de padrões de exposição na vigilância da saúde no trabalho

“…O primeiro valor-limite de exposição para um contaminante do ar foi o estabelecido para o monóxido de carbono, por Max Gruber, em 1883, que, após realizar experiências com animais, submeteu-se ele próprio à concentrações de 210 a 240 ppm durante dois dias, sem registrar sintomas ou sensação de desconforto (Paull, 1984;Cook, apud Arcuri & Cardoso, 1991). Na década de 1920, nos Estados Unidos, começaram a ser elaboradas listas de padrões máximos de exposição e contaminantes do ar, ,geralmente baseados em experimentos animais relativos à toxicidade aguda.…”

Threshold Limit Values: A Balanced Report

“…J.M. Paul1 [1984], in "The Origin and Basis of Threshold Limit Values," describes the changes in thinking about the type of health effects for which TLVs should provide protection: "In the early years of developing exposure limits, the emphasis of the threshold limit concept was toward the prevention of acute stress and illness, and marked symptoms of occupational disease. The term 'threshold limit' was, in effect, synonymous with 'tolerance limit.'…”