MONITORING EXPOSURE TO 4,4'-METHYLENE-BIS(2-CHLOROANILINE) THROUGH THE GAS-CHROMATOGRAPHY MASS-SPECTROMETRY MEASUREMENT OF ADDUCTS TO HEMOGLOBIN

4,4'-Methylene-bis(2-chloroaniline) (MOCA) is widely used as a curing agent in the plastics industry. The determination of the covalently bo und reaction products to hemoglobin (Hb) has been investigated as a bi omonitoring method for occupational exposure to this potential human c arcinogen. Initial studies using the C-14-ring-labeled MOCA showed tha t 24 hr after a single IP dosage to rats (3.74 mumole/kg), 0.08% of th e administered dose was adducted to the Hb, and base hydrolysis libera ted 38% of the bound radioactivity. The only product released on hydro lysis was the parent diamine. A specific and sensitive assay procedure using capillary gas chromatography-mass spectrometry has been develop ed for determining the base-released MOCA adduct down to levels of 20 pmole/g Hb. This method has been used to establish a linear dose-respo nse relationship in IP dosed rats between production of the adduct and dose of MOCA (3.74-44.94 mumole/kg). It is proposed to use analysis o f the Hb adduct as a dosimeter for industrial workers exposed to MOCA.