Background Despite lowering of the permissible exposure level for lead in construction from 200 to 50 "g/m 3 in 1993, excessive lead exposure continues to be a problem. Relatively little data are available from the Midwestern U.S. on the environmental lead concentrations generated during various construction activities and the potential for worker exposure. This study characterized the prevalence of blood lead concentrations in high-risk construction trades in Iowa/Illinois, and identi®ed risk factors for occupational exposure to lead in these construction workers. Methods A sample of 459 workers was selected from the total population of all union members from trade groups of painters, plumbers/pipe®tters, ironworkers, laborers, and electricians. Participants completed an interviewer-administered questionnaire obtaining information on demographics, symptoms, occupational history, work practices, personal protective equipment, and training. Venous blood samples were collected from each participant and analyzed for blood lead (using atomic absorption spectroscopy) and free erythrocyte protoporphyrin levels. Results Blood lead levels (BLLs) of construction workers ranged from 0.1 to 50 "g/dL.
Geometric mean blood lead concentrations by trade group were: laborers (7.6 "g/dL, n 80); painters (5.9 "g/dL, n 83); ironworkers (5.2 "g/dL, n 87); plumbers (4.4 "g/ dL, n 82); electricians (2.4 "g/dL, n 91). Blood lead levels for painters and laborers were signi®cantly higher than other trade groups, and levels for electricians were signi®cantly lower (p < 0.01). Participants reported working primarily on commercial and industrial projects including new construction, renovation, and demolition. There were signi®cant differences between the types of projects performed by different trade groups with laborers performing more highway/bridge renovation (p < 0.01), and plumbers reporting more residential remodeling (p 0.05), repair of water lines containing lead (p 0.04), or work on lead joints (p < 0.01). In addition to trade, elevated blood lead levels were associated with the type of construction project (especially bridge renovation and residential remodeling) and activities that include welding, cutting, rivet busting. The age of the home in which the worker lived, and hobbies such as casting/smelting lead for bullets or sinkers, were also important risk factors. Compliance with OSHA's Construction Lead Standard, and implementation of good occupational health and safety practices in general, was poor. Conclusions Blood lead levels of 459 construction workers differed by the type of trade, type of project and speci®c job activity owing to differences in the inherent exposure