Use for biological monitoring

Organophosphate insecticides also inhibit RBC-ACHE and PCHE. Inhibition of ACHE in erythrocytes is assumed to mirror inhibition of ACHE in the nervous system, which is the receptor of the toxic action, to some extent. Therefore, measurements of RBC-ACHE and PCHE are used for biological monitoring of exposure to OP insecticides (Maroni, 1986). Inhibitions of RBC-ACHE and PCHE activities are correlated with intensity and duration of exposure, although at different levels for each OP compound. Blood ACHE, being the same molecular target as that responsible for acute toxicity in the nervous system, is a true indicator of effect, while PCHE can only be used as an indicator of exposure. 

Halbrook, R.S., Guzman, C.E., Wilkinson, K.J., Watson, A.P., Mimro, N.B., Shugart, L.R. (1992). Rapid whole-blood cholinesterase assay with potential use for biological monitoring during chemical weapons disposal. J. Assoc. Off. Anal. Chem. Int. 75 549-53. 

The determinant for a biological exposure index can be the chemical itself, one or more metabolites, or a characteristic biochemical change induced by the chemical. The specimen used for biological monitoring usually is urine, blood, or exhaled air. For example, the BEI for trichloroethylene includes four determinants ... 

Blood is often used for biological monitoring of exposure to Hg(0) vapour and MeHg. The type of compound is determinative for the distribution of mercury between blood cells and plasma. 

The NTP has a study in progress on "Aryl Amine Adducts in Blood as Indicators of Exposure" (NTP 1991a). In this study, blood samples from 100 workers will be analyzed for hemoglobin o-toluidine adducts. MBOCA will be used to develop an HPLC method for separation and isolation of mitochondrial or total aryl amine-DNA adducts. In addition, the in vitro activation of potential carcinogens will be studied, and a mathematical model for MBOCA distribution, metabolism, and adduct formation will be prepared. The overall objective of the project is to develop a more sensitive adduct isolation procedure to be used for biological monitoring. The contact person for this is K. Cheever(NTP 1991a). 

Of the various tissues/fluids that can be used for biological monitoring, the most common are blood, urine and exhaled air because they are relatively easy to obtain. 

In the production of viscose, the workers are exposed to carbon disulfide. In addition to inhalation exposure, absorption through the skin may be important. It is strongly neurotoxic. Its TLV is 10 ppm and the Finnish OEL 5 ppm. Both carry the skin notation. Urinary 2-thiothiazolidine-4-carboxylic acid concentration can be used for biological monitoring of exposure to carbon disulfide. Its ACGIH BEI is 5 mg/g creatinine (4 mmol/mol creatinine) and the BEI given by the FIOH 2.0 mmol/mol creatinine. 

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