SUNNYSIDE — People attending a community forum on birth defects asked state health officials about possible causes for an unusual cluster of cases in Eastern Washington, including nitrates in the water, pesticide exposure, diet and proximity to the Hanford nuclear reservation.

The Washington state Department of Health has been looking for risk factors and will keep investigating, state epidemiologist Dr. Juliet VanEenwyk said.

“We would love to find a smoking gun, and have things align; if you find a cause, you can prevent. If you can’t find a cause, you can’t prevent,” VanEenwyk told about 25 people Tuesday evening at the Sunnyside Community Center.

Yakima, Benton and Franklin counties have seen an abnormally high rate of anencephaly, a rare and fatal birth defect that occurs when the protective neural tube fails to close at the base of a baby’s skull.

State health officials started investigating in 2012. They scoured hospital and clinic records to identify all possible cases. Investigators studied the medical records of affected women to look for possible common risk factors such as where they lived, whether they were taking their prenatal vitamins, and if they were on private wells for water.

So far, no common cause has stood out, the Yakima Herald-Republic reported.

Another community forum on birth defects was scheduled Wednesday evening at the Benton-Franklin Health District office in Kennewick.

“It absolutely is a worthwhile exercise; I only wish there were more people here” to hear the message, said Dr. Dean Effler, a retired physician who lives in Yakima.

Don and Shirley Dufault who lost a baby to anencephaly in 1977 attended the Sunnyside forum, hoping for answers.

“I’m sure they’re trying,” Shirley Dufault said. “They just have to keep trying.”