An investigation into a rare birth defect affecting babies in Eastern Washington has come to an end. The findings have left more questions than answers.
Disease clusters are notoriously hard to investigate. That proved to be the case for a rare and fatal birth defect in three Washington counties.
Since 2010, anencephaly has shown up in Washington’s Benton, Franklin and Yakima counties at a rate about four times the national average. In many cases, mothers had a miscarriage. When babies survived to term, their brains and skulls did not form completely.
Most recently there have been four cases of anencephaly with estimated delivery dates in 2016 and 2017, bringing the total to 45 cases since 2010.
State health officials have worked with the Centers for Disease Control, nurses, doctors and researchers from other states that have seen similar anencephaly clusters. After almost three years of sifting through data and interviewing mothers -- often months after their pregnancies -- an advisory committee leading the investigation has come up with no real answers.
Washington epidemiologist Cathy Wasserman said the committee feels they’ve eliminated many popular theories.
“Our case control analyses and interviews have not identified a single preventable cause that we can act on,” Wasserman said.
The panel reported that it could not find links to pesticide exposure, nitrate pollution in drinking water, or exposure to Hanford radiation.
Mothers also appeared to be taking the right amount of folic acid vitamins at the right time -- a lack of folic acid is a common cause for these types of defects.
Officials said they would continue to monitor the number of anencephaly cases through January 2018. They also plan to continue advising women of childbearing age to take folic acid supplements.