Context: Lowlevel lead exposure may increase the risk for a number of chroni c agerelated diseases. Several studies have documented the presence of lead in lenses with cataract. The intrusion of lead into the lens may alter lens redox status and cause protein conformational changes that decrease lens transparency. Objective: To determine the relationship of cumulative lead exposure with the d evelopment of cataract. Design, Setting, and Participants: Tibial (cortical) and patellar (trabecular)bone lead levels were measured by K xray fluorescence between 1991 and 1999 in a subset of participants in the Normative Aging Study ( NAS), a Bostonbased longitudinal study of aging in men. Among the first 795 NA S participants to have bone lead levels measured, we reviewed eye examination da ta (collected routinely every 3-5 years) for the period after the bone lead mea surements were taken. We limited the population to men aged 60 years and older w ho had sufficient eye examination information available (n=642). Blood lead leve ls were also measured. Main Outcome Measures: Cataract assessment was done while masked to the lead level results. A participant was considered to have cataract if there was documentation for either eye of cataract surgery or a cataract gra ded clinically as 3+or higher on a 4-point scale. Odds ratios (ORs) and 95%co nfidence intervals (CIs) were calculated as estimates of the magnitude and signi ficance of the relationship of lead exposure with cataract, in logistic regressi on models. Results: The mean age of the study participants was 69 years and cata ract was identified in 122 men. The ageadjusted OR (95%CI) for cataract for m en in the highest vs lowest quintile of tibia lead level was 2.68 (1.31-5.50). Further adjustment for packyears of cigarette smoking, diabetes, blood lead le vels, and intake of vitamin C, vitamin E, and carotenoids resulted in an OR of 3 .19 (95%CI, 1.48-6.90). For patella lead level, there was an increased risk of cataract in the highest vs lowest quintile (OR, 1.88; 95%CI, 0.88-4.02), bu t the trend was not significant (P=.16). Blood lead levels, more indicative of s hortterm exposure levels, were not significantly associated with cataract (OR, 0.89; 95%CI, 0.46-1.72; P=.73). Conclusions: These epidemiologicaldata sugges t that accumulatedlead exposure, such as that commonly experienced by adults in the United States, may be an important unrecognized risk factor for cataract. Th is research suggests that reduction of lead exposure could help decrease the glo bal burden of cataract. Context: Lowlevel lead exposure may increase the risk for a number of chroni c agerelated diseases. Several studies have documented the presence of lead in lenses with cataract. The intrusion of lead into the lens may alter lens redox status and cause protein Objective: To determine the relationship of cumulative lead exposure with the d evelopment of cataract. Design, Setting, and Participants: Tibial (cortical) and patellar (trabecular) bone lead levels were measured by K x  ray fluorescence between 1991 and 1999 in a subset of participants in the Normative Aging Study (NAS), a Bostonbased longitudinal study of aging in men. Among the first 795 NA S participants to have bone lead levels measured, we reviewed eye examination da ta (collected routinely every 3-5 years) for the period after the bone lead mea surements were taken. We limited the population to men aged 60 years and older w ho had sufficient eye examinati on information available (n = 642). Blood lead leve ls were also measured. Main Outcome Measures: Cataract assessment was done while masked to the lead level results. A participant was considered to have cataract if there was documentation for either eye of cataract surgery or a cataract gradd clinically as 3 + or higher on a 4-point scale. Odds ratios (ORs) and 95% co nfidence intervals (CIs) were calculated as estimates of the magnitude and signi ficance of the relationship of lead exposure with cataract , in logistic regressi on models. Results: The mean age of the study participants was 69 years and cataract was identified in 122 men. The ageadjusted OR (95% CI) for cataract for m in the highest vs lowest quintile of Further adjustment for pack-of-cigarettes, diabetes, blood lead levels, and intake of vitamin C, vitamin E, and carotenoid resulted in an OR of 3.19 (95% CI, 1.48-6.90). For patella lead level, there was an incr eased risk ofcataract in the highest vs lowest quintile (OR, 1.88; 95% CI, 0.88-4.02) Blood, t tt trend was not significant (P = .16). Blood lead levels, more indicative of s hortterm exposure levels, were not significantly associated with cataract (OR, 0.89; 95% CI, 0.46-1.72; P = .73). Conclusions: These epidemiological data sugges t that accumulatedlead exposure, such as that that used experienced by adults in the United States, may be an important unrecognized risk factor for cataract. Th is research suggests that reduction of lead exposure could help decrease the glo bal burden of cataract.