Comparative analysis of environmental exposures and orofacial clefts in the Democratic Republic of Congo and the Philippines

BACKGROUND: Literature suggests that chemical exposures may be potential risk factors for orofacial clefts. While prior studies agree that the etiology of cleft lip with or without cleft palate is multifactorial in terms of genetics and exposures, there is wide variability in the estimate of risk associated with several environmental exposures. In particular, risk factor data in underserved minority populations are scarce and merit further investigation.

METHODS: As part of an epidemiologic-genetic study between Operation Smile, University of Southern California and Children’s Hospital Los Angeles, maternal and paternal exposure data during pregnancy were collected from 2011 to 2013 using interviewer-administrated questionnaires in the Democratic Republic of Congo (DRC) and the Philippines. Chi-squared, Student t and Fischer’s exact tests were used to compare groups.

RESULTS: In the DRC and Philippines, exposure to industrial chemicals (p<0.01), rural residence (p<0.01) and public or well-water consumption (p<0.05), were more frequent among mothers of cases compared to mothers of controls. When comparing exposure trends for the Congolese and Filipino populations, significantly more cases in the DRC had exposures to industrial chemicals (13.5% vs. 8.5%, p<0.01), rural residence (9.5% vs. 53.2%, p<0.01), well-water consumption (10.2% vs. 40.0% P<0.01) and public water consumption (76.5% vs. 8%, p<0.01).

CONCLUSION: With considerable lifestyle and cultural differences in the DRC and Philippines, both populations have similar exposure risks for cleft disease while having significantly different incidences of exposure. The nuances of these relationships are key to deciphering the full picture of cleft risk around the world.