Description
Lead poisoning has been documented since antiquity but occupational lead intoxication still continues to occur (Rampe] 1989). Now there is a growing consensus that low levels of lead exposure often do not result in the manifestation of toxic symptoms, but may have sub- clinical toxicity on haemopoit ic and renal system (Marks (1985; Hunter 1986; Goyer 1990). Such toxicities are reported even at blood lead concentrations which were thought to be safe (60-80 ~ag/d]) a decade ago (Who 1986; Staessen eta], 1992). One of the several effects of lead, is inhibition of erythrocyte de] ta-amino] evu] inic acid dehydratase (d-ALAD), rate limiting enzyme of the heme synthesis (Gibsson et a] 1968; Sassa et a] 1973; Marks 1985). Similar effect on d-ALAD has been reported even at the blood lead concentrations of 20-30 ~g/d] which are much below the toxic limits of 60 ~g/d] (WHO 1986; Somashekhariah et al, 1990).
