Cleft lip/ cleft palate births and radioactivity in water sources in Harris County, Texas

Introduction: Radon and radium are radioactive elements associated with cleft deformities. Low-level concentrations of these elements are present in the domestic water supply of Harris County, Texas. The present study investigated whether this contamination was associated with an increased rate of county births with cleft deformities from 1989-1994; it also evaluated differences between census tract-level vs. zip code-level geocoding.

Methods: Radon and radium concentration levels were derived from earlier studies. Residential addresses of county births with cleft deformities were geocoded and aggregated to the census tract-level. Data was analyzed using various statistical measures and compared with to a study by Walston (2007) which geocoded and aggregated residential addresses to the zip code-level.

Results: Cleft deformity rates were 1.4-1.6 times greater for census tracts with elevated radium or radon. For radium, the association was not statistically significant (p=0.28 and p=0.43); for radon it was borderline significant (p = 0.06) in a univariate model and significant (p = 0.046) in a multivariate model. The primary difference between the results of the present study and those of Walston (2007) was that the latter study found a statistically significant association between radium concentrations and the prevalence of cleft deformities while the present study did not.

Conclusions: Some association exists between radon contamination and cleft deformities in Harris County, Texas which warrants further investigation. While in the present study the two aggregated geocoding methods produced largely similar results, census track-level data circumvents several concerns associated with zip code-level data.