EFFECT OF AIRBORNE LEAD ON LEAD LEVELS OF BLOOD TAIL VERTEBRAE, ILIACCREST AND EPIPHYSES OF THE RAT

Lead has no metabolic role in the human body and its presence is assoc iated with various toxic effects. Groups Of 20 inbred rats were expose d to: I) 'clean air' (0.05 mu g Pb per m(3)) for 70 days; 2) 77 mu g P b per m(3) for 70 days; 3) 249 mu g Pb per m(3) for 28 days; and 4) 15 46 mu g Pb per m(3) for 50 days. Half the rats in each group were then killed and the other half kept in 'clean air' until the blood lead of groups 1-3 had returned to normal. Tail vertebrae, iliac crest and ep iphyses' radius, and blood were analysed fop lead by atomic absorption spectrophotometry. In the rats killed immediately after exposure, the [end levels of blood, iliac crest, epiphyses and rail vertebrae diffe red significantly among all 4 groups, except between groups 2 and 3 fo r the tail vertebrae, indicating the importance of the combined effect of airborne lend concentration and length of exposure. A higher level was associated throughout, with nn increase in the period of exposure . Far the post-exposure rats, the blood showed no significant differen ces among groups 1, 2 and 3. However for tail vertebrae, iliac crest a nd epiphyses no significant differences were found between groups 2 an d 3. Lead turnover had the following sequence: blood (soft tissue) > i liac crest (trabecular bane) > epiphyses (trabecular and compact bone) > tail vertebrae (compact bane). Blood lead became supplemented throu gh the process of bone remobilization and different bone compartments for the metal appear to exist.