[Knowledge status of the effect of long-term heat exposure on health]

The actual occupational hygienic limit values for heat stress are based only on acute thermic effects. It cannot, however, be excluded that occupational heat exposure lasting for many years is able to cause chronic alterations of health status to such an extent that long-term effects have to be considered in occupational hygienic heat stress evaluation. In the present paper the essential effects of long-lasting heat stress are discussed on the basis of information from specialized literature, referring primarily to circulation system and water and electrolyte balance. Because of contradictions and insufficient reliability of the present results, further scientific work, especially concerted epidemiological research, is required to answer open questions. Concerning the health protection of heat exposed workers, conclusions are deduced, which can be drawn from the analyzed results already now.