Biological Threshold Limit Values

Keywords biological monitoring biological threshold limit value body fluids ... 

In order to fill in these blanks and to give a more real reflection of the picture of exposure, the biological monitoring of harmful substances should be carried out and, especially its kinetic properties in the body should be established. Toxicokinetic models allow to estimate the Biological Threshold Limit Values (Reference Values), which serve to protect the individuals effectively from chemical-induced health risks. 

It has been shown that all doses of arsenic trioxide are characterized by different toxicokinetics parameters. Arsenic compounds have long half-times and the tendency to accumulate in the body. The excretion rate decreased with decreasing blood concentration. The present study confirms the ability of toxicokinetic models to improve the study of various toxic substances and to estimate the Biological Threshold Limit Values. 

H. Roels, J.P. Gennart, R. Lauwerys, J.P. Bucher, J. Malchaire, and S. Bernard, Surveillance of workers exposed to mercury vapor Validation of a previously proposed biological threshold limit value for mercury concentration in urine. Am. J. Ind. Med. 7 45, 1985. 

For risk assessment in the case of vanadium uptake urine is the matrix of choice. The collection of urine is non-invasive and is practical under routine conditions. Moreover this parameter is more sensitive for diagnostic purposes than the vanadium concentration in blood. A tentative biological threshold limit value of 50 mg/kg creatinine has been proposed for urinary vanadium (Lauwerys, 1983). 

Threshold Limit Values for Chemical Substances and Physical Agents and Biological Exposure Indexes," Proceedings of American Conference of Government Hygienists, Cincinnati, Ohio, 1996. 

Threshold Limit Values and Biological Exposure Indices for 1989—1990," Mmerican Conference of Governmental Industrial Hygienists, Cincinnati, Ohio, 1989. 

American Conference of Governmental Industrial Hygienists. Threshold limit values for chemical substances and physical agents and biological exposure indices. ACGIH, Cincinnati, OH. 1999. 

The Chemical Substances Threshold Limit Values Committee classifies certain substances found in the occupational environment as either confirmed or suspected human carcinogens. The present listing of substances that have been identified as carcinogens takes two forms those for which a TLV has b n assigned and those for which environmental and exposure conditions have not been sufficiently defined to assign a TLV. Where a TLV has been assigned, it does not necessarily imply the existence of a biological threshold however, if exposures are controlled to this level, we would not expect to see a measurable increase in cancer incidence or mortality. 

There are three biological exposure indices (BEls) for exposure to trichloroethylene at the ACGIH threshold limit value time-weighted average (TLV-TWA) of 50 ppm (ACGIH 1996). When measured at the end of a 40-hour workweek, TCA in urine is approximately 100 mg/g creatinine when measured at the end of an 8-hour shift at the end of a workweek TCA and trichloroethanol in urine is approximately 300 mg/g creatinine, and free trichloroethanol in blood is approximately 4 mg/L. 

ACGIH maintains annual editions of the TLVs and BEIs which are used worldwide as a guide for evaluation and control of workplace exposures to chemical substances and physical agents. Threshold Limit Value (TLV ) occupational exposure guidelines are recommended for more than 700 chemical substances and physical agents. There are more than 50 Biological Exposure Indices (BEIs ) that cover more than 80 chemical substances. 

ACGIH (American Conference of Governmental Industrial Hygienists). 1999. Threshold Limit Values (TLVs) for Chemical and Physical Agents and Biological Exposure Indices (BEIs). Cincinnati, OH ACGIH. 

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