The Risk of Orofacial Cleft Lip/Palate Due to Maternal Ambient Air Pollution Exposure: A Call for Further Research in South Africa

Caradee Y Wright; Thandi Kapwata; Bianca Wernecke; Helen Malherbe; Kurt-W Bütow; Natasha Naidoo; Rebecca M Garland; Anzel de Lange; Gareth E Murray; OPERATION SMILE

doi:10.5334/aogh.4007

The Risk of Orofacial Cleft Lip/Palate Due to Maternal Ambient Air Pollution Exposure: A Call for Further Research in South Africa

Ann Glob Health. 2023 Jan 27;89(1):6. doi: 10.5334/aogh.4007. eCollection 2023.

Authors

Caradee Y Wright^{1

2}, Thandi Kapwata^{3

4}, Bianca Wernecke^{3

4}, Helen Malherbe⁵, Kurt-W Bütow⁶, Natasha Naidoo¹, Rebecca M Garland², Anzel de Lange⁷, Gareth E Murray³; OPERATION SMILE

Affiliations

¹ Environment and Health Research Unit, South African Medical Research Council, Pretoria, ZA.
² Department of Geography, Geoinformatics and Meteorology, University of Pretoria, Pretoria, ZA.
³ Environment and Health Research Unit, South African Medical Research Council, Johannesburg, ZA.
⁴ Department of Environmental Health, Faculty of Health Sciences, University of Johannesburg, Johannesburg, ZA.
⁵ Rare Diseases South Africa, The Station Bryanston, 63 Peter Place, Sandton, ZA.
⁶ Department of Maxillo-Facial and Oral Surgery, University of Pretoria, and Life-Wilgers Hospital, Pretoria, ZA.
⁷ Department of Geography and Environmental Studies, University of Limpopo, Limpopo, ZA.

Abstract

Background: Despite being underreported, orofacial cleft lip/palate (CLP) remains in the top five of South Africa's most common congenital disorders. Maternal air pollution exposure has been associated with CLP in neonates. South Africa has high air pollution levels due to domestic burning practices, coal-fired power plants, mining, industry, and traffic pollution, among other sources. We investigated air pollutant levels in geographic locations of CLP cases.

Methods: In a retrospective case series study (2006-2020) from a combined dataset by a Gauteng surgeon and South African Operation Smile, the maternal address at pregnancy was obtained for 2,515 CLP cases. Data from the South African Air Quality Information System was used to calculate annual averages of particulate matter (PM) concentrations of particles < 10 µm (PM₁₀) and < 2.5 µm (PM_2.5). Correlation analysis determined the relationship between average PM_2.5/PM₁₀ concentrations and CLP birth prevalence. Hotspot analysis was done using the Average Nearest Neighbor tool in ArcGIS.

Results: Correlation analysis showed an increasing trend of CLP birth prevalence to PM₁₀ (CC = 0.61, 95% CI = 0.38-0.77, p < 0.001) and PM_2.5 (CC = 0.63, 95% CI = 0.42-0.77, p < 0.001). Hot spot analysis revealed that areas with higher concentrations of PM₁₀ and PM_2.5 had a higher proclivity for maternal residence (z-score = -68.2, p < 0.001). CLP birth prevalence hotspot clusters were identified in district municipalities in the provinces of Gauteng, Limpopo, North-West, Mpumalanga, and Free State. KwaZulu-Natal and Eastern Cape had lower PM₁₀ and PM_2.5 concentrations and were cold spot clusters.

Conclusions: Maternal exposure to air pollution is known to impact the fetal environment and increase CLP risk. We discovered enough evidence of an effect to warrant further investigation. We advocate for a concerted effort by the government, physicians, researchers, non-government organizations working with CLP patients, and others to collect quality data on all maternal information and pollutant levels in all provinces of South Africa. Collaboration and data sharing for additional research will help us better understand the impact of air pollution on CLP in South Africa.

Keywords: air pollution; birth defect; congenital disorder; craniofacial anomalies; environmental health; orofacial cleft lip/palate; particulate matter.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Air Pollutants* / adverse effects
Air Pollutants* / analysis
Air Pollution* / adverse effects
Air Pollution* / analysis
Cleft Lip* / epidemiology
Cleft Palate* / epidemiology
Female
Humans
Infant, Newborn
Particulate Matter / adverse effects
Particulate Matter / analysis
Pregnancy
Retrospective Studies
South Africa / epidemiology

Substances

Air Pollutants
Particulate Matter

Grants and funding

We thank the South African Medical Research Council for funding via National Treasury; Professor Bütow and staff for their assistance with the database; and Operation Smile for provision of their data for this study. We also thank the South African Air Quality Information System for air quality data.