Analysis of variation in blood lead levels in Melbourne families.

Blood lead levels were measured in 651 subjects, aged from six to 91 years, from 83 Melbourne families. Lead levels were higher in males than in females, and increased with age (to 60 years), with haematocrit, and with cigarette smoking. Blood lead levels tended to increase with levels of blood pressure, and this weak positive correlation persisted after adjusting for age and sex differences. Blood lead levels were similar in members of the same family; the familial correlation was greatest for siblings during childhood, and least for spouses. This suggests that shared (home) environment has a greater influence on blood lead levels in young people than on those in adults. Over all, our findings highlight the importance of environmental factors as causes of variation in blood lead levels, and the importance of quality control in studies of blood lead.