THE EFFECT OF AIRBORNE LEAD ON LEAD LEVELS OF BLOOD, INCISORS AND ALVEOLAR BONE OF RATS

Groups of 20 inbred rats were exposed to: (1) "clean air" (0.05-mu-g Pb/m3) for 70 days; (2) 77-mu-g Pb/m3 for 70 days; (3) 249-mu-g Pb/m3 for 28 days; and (4) 1546-mu-g Pb/m3 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. That half of the incisors which had been completely renewed during the experimental period, as well as the alveolar bone of each rat, were analysed for lead by atomic absorption spectrophotometry. In the rats killed immediately after exposure, the lead levels of the incisors and alveolar bone showed significant differences (p < 0.05) among all four groups, except between groups 2 and 3, indicating the importance of the combined effect of airborne lead concentration and length of exposure. For blood, significant differences (p < 0.05) were found among all groups. For the post-exposure rats, the incisors and blood showed no significant differences (p < 0.05) among groups 1, 2 and 3. For alveolar bone, significant differences were not found (p > 0.05) between groups 2 and 3. It can be concluded that during lead exposure the alveolar bone transformation was the highest and that of incisor tissue just lower, and that blood lead became supplemented through the process of remobilization from alveolar bone, as reported for other bones.