To the Editor.
—Dr Hu and colleagues1 report a correlation between lead levels and hypertension. It is well known that the lower socioeconomic groups suffer poorer health than the higher socioeconomic groups. And it would be expected that children in lower socioeconomic groups would be more likely to have been exposed to lead (eg, ingestion of peeling paint indoors, absorption of paint dust from sandblasting nearby bridges) than would children from higher socioeconomic groups. For this reason, it would be surprising not to find a correlation between health problems and lead levels.It would be of interest if an additional variable representing the socioeconomic group of the subjects' families (when the subjects were children) was included in the analysis. Would there still be a significant correlation of health problems with lead level? Another variable that could be considered is the subjects' occupation: painters and plumbers, with higher than average