Substantial decrease of blood lead in Swedish children, 1978-94, associated with petrol lead.

OBJECTIVES

To study the potential impact of environmental exposure to petrol lead, residential area, age, sex, and lead exposing hobby, on blood lead concentrations (BPb) in children.

METHODS

In the south of Sweden, yearly from 1978-94, BPb was measured in 1230 boys and 1211 girls, aged between 3 and 19 (median 10; quartiles 9 and 12) years.

RESULTS

For the samples of 1978, the geometric mean (GM) was 67 (range 30-250) micrograms/l in boys and 53 (18-161) micrograms/l in girls, whereas the corresponding GMs for 1994 were 27 (12-122) and 23 (12-97) micrograms/l. The sex difference was present only in children over eight. Moreover, residential area affected BPb; in particular, children living near a smelter area had raised BPbs. There was a clear ecological relation between BPb (adjusted GM) and annual lead quantity in petrol sold in Sweden, which was estimated to be 1637 tonnes in 1976 and 133 tonnes in 1993 (P < 0.001, ecological linear regression analysis, where a two year lag of petrol lead was applied). In the 171 boys and 165 girls who were sampled twice with an interval of one to four years, the decreases in BPb were estimated to be 6% (95% confidence interval 4%-8%) and 10% (8%-13%)/year, respectively.

CONCLUSIONS

The present report points out the considerable beneficial effect of the gradual banning of petrol lead on the lead exposure affecting the population and differential sex specific BPb patterns due to a pronounced age effect in girls, which may be caused by older girls' lower food intake per kg of body weight, lower lung ventilation, cleaner life style, and loss of blood lead through menstrual bleedings.