Occupational lead exposure and blood pressure.

Abstract

Recent community studies have suggested that low level lead exposure is significantly associated with blood pressure in the general population. This finding is inconsistent with the results of recent occupational studies of lead exposed workers, although the occupational studies contained serious methodological weaknesses. The present study examined the relation between occupational lead exposure and diastolic and systolic blood pressure in randomly selected samples of 270 exposed and 158 non-exposed workers. Four exposure indicators were examined: employment at a lead battery plant v a control plant, current blood lead value, current zinc protoporphyrin value, and time weighted average blood lead value. After controlling for other known risk factors such as age, education, income, cigarette usage, alcohol consumption, and exercise, the associations between exposure and blood pressure were small and non-significant. In the absence of a biologically feasible hypothesis regarding the mechanism by which low level lead exposure would influence blood pressure the present findings challenge the validity of the general population association.The relation between lead exposure and rises in blood pressure has recently received a great deal of attention because of the implication that mortality from cardiovascular and cerebrovascular disease might be reduced by lowering lead values in the environment.'1 Early reports focused on workers in the lead industries and described hypertension and nephritis as frequent manifestations of lead exposure.23 More recently, Dingwall-Fordyce and Lane showed an excess mortality from cerebrovascular disease in lead exposed workers with 25 years of exposure occurring before 1961.4 The excess mortality was greater for workers dying between 1926 and 1950 than for workers dying between 1951 and 1961. With one exception5 studies conducted since the classic research of Dingwall-Fordyce and Lane have confirmed the original findings.6-9 It should be noted that these studies were conducted in plants with extremely high levels of exposure to lead, and the study that failed to find an excess in mortality' was conducted after exposure had been substantially reduced. Because of these extremely high exposures and the almost inevitable nephrotoxicity, the most parsimonious explanation of the excess cardiovascular and cerebrovascular mortality is hypertension secondary to renal disease rather than primary hypertension.Two studies have directly examined the relation

Occupational exposure to lead, kidney function tests, and blood pressure

“…Ramirez-Cervantes et al [1978] studied 652 lead foundry workers with at least 5 years of exposure and found no differences in systolic and diastolic blood pressure. In another study, Parkinson et al [1987] examined the relationship between occupational exposure to lead and diastolic and systolic blood pressure in 270 exposed and 158 nonexposed individuals. After considering factors such as age, education, smok-ing habit, alcohol ingestion, and physical activity, they concluded that the association between exposure to lead and blood pressure was weak and nonsignificant.…”

Effect of lead on blood pressure in occupationally nonexposed men

“…Thus a link has been found between blood lead in low concentrations and children's intelligence [Baghurst et al, 1992;Ruff et al, 19931. More important in occupational medicine, the concentration of blood lead was related to blood pressure regulation, but the literature on this subject is controversial [Parkinson et al, 1987;Landrigan, 1991;Goyer, 19931.…”

Association between bone lead concentration and blood pressure among young adults

“…Among occupationally and environmentally exposed older adults, associations between BP and blood lead concentrations have been observed in some, but not all, investigations [Parkinson et al, 1987;Hertz-Picciotto and Croft, 1993]. The current study is the first to document a strong association between BP and bone lead among young adults who had very low blood lead concentrations at the time of the investigation, but who were exposed to lead as children.…”

“…Not all investigations of the relationship between blood lead concentration and BP have produced positive associations, however [Parkinson et al, 1987;Elwood et al, 1988;Grandjean et al, 1989;Staessen et al, 1990;Sokas et al, 1995;Staessen et al, 1996;Wu et al, 1996;Ehrlich et al, 1998;Nordberg et al, 2000], several suggestions are offered to explain the heterogeneity of results observed. First, it is possible that uncontrolled confounding biased the results of some studies.…”