Lead concentration in whole blood of a representative sample of 471 subjects aged 20 to 74 years and living in Basle was determined in 1989/90 by flame atomic absorption spectrophotometry. The participants in the cross-sectional study filled in a questionnaire on demographic factors, nutrition and drinking habits. The age-adjusted geometrical mean blood lead level was 0.38 +/- 0.19 mumol/litre of whole blood for males, and 0.29 +/- 0.17 mumol/litre for females. The average lead burden was about 30% below the mean concentration found in a comparable population in Western Switzerland five years earlier. Lead emissions in Switzerland decreased by about 40% from 1984 to 1990 through restriction of lead in petrol. This offers the most plausible explanation for the low blood lead levels found in Basle. Sex, age, occupation (employment in painting or printing, construction or the metal processing industry), smoking and alcohol intake (especially wine consumption) were identified as independent blood lead predictors in a multiple linear regression analysis. Participants who consumed alcohol daily had blood lead concentrations on average 12% higher than those of abstinent subjects. Regular smokers had an unconfounded average blood lead level 8% above that of people who never smoked. Place of residence and hourly frequency of cars in that area were not identified as independent predictors in the model. The analysis of 99 different wines on the market in Basle showed an average lead concentration of 50 +/- 17 micrograms/litre wine. Compared to an estimated 25 micrograms daily nutritional intake of lead in Switzerland the value appeared to be high.(ABSTRACT TRUNCATED AT 250 WORDS)