Study Examines Effect of 2011 Tohoku Disaster on Prevalence of Cleft Lip, Palate

Alyssa KirkmanACPA News, Journal

  • Study compared disaster-affected CL/P data to similar data collected following Hurricane Katrina
  • Race, cultural differences may affect prevalence of CL/P following a natural disaster

CHAPEL HILL, N.C. / Oct. 22, 2019 – Did the 2011 Tohoku earthquake and tsunami affect the birth prevalence of cleft lip and/or palate in Miyagi Prefecture? That was the question addressed in a recent study, “The Birth Prevalence of Cleft Lip and/or Cleft Palate After the 2011 Tohoku Earthquake and Tsunami”. The research results were published in the October 2019 issue of The Cleft Palate-Craniofacial Journal (CPCJ).

“Disasters from natural causes or human actions happen intermittently, with occurrence frequency inversely correlated to the magnitude of the event. Stated another way, there are many small events for every one that causes major destructions. The magnitude 9.1 Tohoku earthquake on April 7th, 2011 that caused Level 7 meltdown of three nuclear reactors in Fukushima Daiichi certainly qualifies as a major disaster,” said Jack C. Yu, DMD, MD, MS ED, Editor of CPCJ. “Like 9/11 and Katrina, these clearly marked events in time allow for population-based analyses to detect changes in prevalence of birth defects before and after the event.”

The Tohoku earthquake and tsunami, also known as the Great East Japan Earthquake, occurred on March 11, 2011, and was one of the largest natural disasters every recorded. Widespread damage to property and infrastructure affected thousands of people and had a dramatic impact on human health and well-being.

“The exact pathology of cleft lip and/or cleft palate (CL/P) remains unknown, but it is widely accepted that multiple genetic and environmental factors play a role,” explained Yoshimichi Imai, lead researcher. “In New Orleans, after Hurricane Katrina, an increase in cleft cases was attributed to an increase in stress and/or teratogenic risk factors. Our research sought to investigate whether the Tohoku disaster would result in similar results with CL/P occurrence.”

The study focused on the disaster-affected period from December 1, 2011, to November 30, 2012. Researchers compared their data to a control period of five years—from January 1, 2006, to December 31, 2010—when there were no exposures to environmental hazards or significant events.

A retrospective review of medical records from two hospitals that regularly treat more than five cleft cases per year in Miyagi Prefecture revealed the number of live births with CL/P during the study’s timeframe. Data included types of cleft, gender, birth date, resident municipality, and ethnicity. Logistic regression analyses were used to estimate the impact on the birth prevalence of each cleft type associated with the 2011 disaster. In addition, the odds of cleft type among all live births in the disaster-affected period was compared to the control period.

All of the CL/P patients in the study were Asian. In the control period, 97,902 live births were registered, including 135 with CL/P and 51 isolated cleft palate (iCP) cases. There were more males overall, but more females within this group had iCP. In the disaster-affected period, 18,605 live births were registered, including 31 CL/P and six iCP. The gender ratio for iCP was 1:1; however, due to the small number of cases, researchers noted it was not possible to statistically analyze the difference.

After comparing the birth prevalence of CL/P in the disaster-affected period with the control period, researchers did not find a significant increase in the birth prevalence of cleft palate cases during the disaster-affected period.

“Racial differences may account for why our study did not find an increase in cleft palate cases following the 2011 Tohoku earthquake and tsunami. Following Hurricane Katrina, cleft birth prevalence notably increased among African Americans, but not among white individuals. The fact that our study’s participants were all Asian may have influenced the results,” Imai said. “In addition, unlike post-Hurricane Katrina, teratogens were not detected in the atmosphere after the Tohoku disaster. Psychological conditions may have also been better since distinct cultures react differently to crises.”

“Analysis did not show a statistically significant increase in the prevalence of orofacial cleft one year after the earthquake and tsunami of 2011. This is different from similar analyses after Hurricane Katrina of 2005, reported by Goenjian et al. (CPCJ 48:6, 757-761, 2011),” said Yu.  “In addition to many differences in the nature of the disasters, there are also difference in the populations studied. The Japanese population being much more homogeneous while the population in Greater New Orleans being very heterogeneous. The key finding of the Imai paper is that despite such a major disaster that changed earth’ s rotational axis and angular velocity, killing 19,000 people and displacing more than a quarter million residents, there was no significant change in the prevalence of orofacial clefting.”

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About the American Cleft Palate-Craniofacial Association
The American Cleft Palate-Craniofacial Association (ACPA) is a nonprofit 501(c)(3) association of interested individuals and health care professionals who treat and/or perform research on oral cleft and craniofacial conditions. Since 1943, ACPA has worked to optimize outcomes for individuals with oral cleft and craniofacial conditions through education, support, research, advocacy and interdisciplinary team care. ACPA also provides information to affected individuals and families and seeks to educate the public about facial differences through its ACPA Family Services program. For more information, please visit