Incidence of hypertension among lead workers. A follow-up study based on regular control over 20 years.

Three hundred and sixty-four workers employed in an accumulator factory had at least three bloodpressure determinations during 1962 in a study of the relation between lead exposure and the incidence of hypertension. In this group 46 workers were found to have hypertension; the expected incidence was 51. Two hundred and seventy-three of the total group, all over 35 years, had been employed for a sufficiently long time to be considered as having had a long-term exposure to lead. On the basis of urinary coproporphyrin tests, they were divided into a lead-affected' group (141) and a non-lead-affected' group (132). There were 22 persons with hypertension in the former group, and 20 in the latter. There was no significant difference in the appearance of hypertension in these two groups either from the standpoint of age or from the duration of exposure to lead. Two hundred and sixty-five workers had been employed at the factory for 10 or more years, and 82 of these for more than 20 years. There was a positive correlation between the incidence of hypertension and the duration of employment, but no difference between the lead-affected' and non-lead-affected' groups. This observation is understandable in view of the increasing incidence of hypertension with advancing age. The study shows that workers in an accumulator factory, in which the working conditions are inspected and controlled regularly and in which the workers themselves are examined regularly for the influence of lead, are not more prone to hypertension than the general population. In view of the possibility of vascular damage after exposure to lead, blood pressures in lead-workers should be watched, and treatment started early if hypertension is found.