Lead Exposure Associated with Higher Levels of Tooth Decay

Environmental lead exposure is associated with an increased prevalence of dental caries in the US population, especially among poor and disadvantaged children, according to a study in the June 23/30 issue of The Journal of the American Medical Association (JAMA. 1999; 281:2294–2298).

Mark E. Moss, D.D.S., Ph.D., of the University of Rochester School of Medicine and Dentistry in Rochester, NY, and colleagues studied a total of 24,901 persons aged 2 years and older who participated in the Third National Health and Nutrition Examination Survey (NHANES III) from 1988 to 1994 to examine the relationship between blood lead levels and dental caries. The researchers report that the blood lead level was significantly associated with the number of affected surfaces (decayed, missing, or filled) for both deciduous and permanent teeth in all age groups, even after adjusting for sociodemographic characteristics, diet, and dental care.

Among children ages 5 to 17 years, a 0.24-µmol/L (5-µg/dL) change in blood lead level was associated with an 80% elevated risk of tooth decay, according to a summary of the JAMA article. The researchers estimate that for the general population, 13.5% of tooth decay among 5- to 17-year-olds is attributable to high levels of lead exposure, and 9.6% of the tooth decay is attributable to moderate levels of lead exposure.

The researchers note that a recent study showed that family income level was particularly linked with the proportion of children having decayed teeth. "The results of the present analyses suggest that environmental lead exposure may explain, at least in part, the disproportionately high rate of dental caries among disadvantaged children and adolescents," the authors write.

But this study suggests that the association between poverty and tooth decay is only partially explained by lead exposure. The authors add that they can't demonstrate conclusively that environmental lead exposure is causally linked to dental caries on the basis of observational data alone, the article summary says.

The researchers say their data indicate that approximately 2.7 million excess cases of dental caries in older children and adolescents may be attributable to environmental lead exposure. "If a causal association between environmental lead exposure and dental caries is substantiated, it would have important implications concerning the need to broaden the focus of health interventions for dental caries beyond modifying dietary habits, improving personal oral hygiene behaviors, and increasing fluoride exposure in high-risk groups," they conclude.

According to information cited in the study, by age 17 years, 84% of US adolescents have experienced tooth decay in their permanent teeth—on average involving eight tooth surfaces.