Toxicology of Industrial Compounds

Table 6.1 Methods for the determination of protein adducts
a An approximate mean sensitivity is given in pmol (=10 −12 mol) adducts/g
haemoglobin.
Table 6.2 Methods for the determination of DNA adducts
Lack of bioavailability of 3,3′-dichlorobenzidine from
diarylide pigments
P.SAGELSDORFF 81
a An approximate mean sensitivity is given in fmol (=10 −15 mol) adducts/mg DNA.
3,3′-Dichlorobenzidine is an important intermediate in the production of
diarylide pigments and azo dyes. Some of these pigments have been tested
in long term studies and shown to exert no specific toxicological effects and
to be not carcinogenic to experimental animals (ETAD Report, 1990).
However, there might be a theoretical hazard after metabolic splitting of the
pigments into DCB, a known animal carcinogen (IARC, 1982). DCB and
its N-acetylated metabolite are N-hydroxylated and oxidised to the
corresponding nitroso compound which binds to haemoglobin. Since no
repair of haemoglobin adducts occurs, these adducts cumulate during the