SALINA, Kan. (AP) — Kansas health officials are trying to determine what is causing elevated lead levels among about 30 children in central Kansas’ Saline County.

Farah Ahmed, of the Kansas Department of Health and Environment, says an investigation will be held through July.

Since the start of 2015, elevated lead levels have been detected in the blood of 32 children, age 15 and younger.

The Salina Journal reports that health officials discussed the issue with the public Tuesday night in Salina. Ahmed says health officials will review the potential sources for lead exposure, including grandparents’ houses, child care centers, toys, food, cosmetics and where the parents work.

Saline County has a history of elevated blood lead levels, with 21 cases in 2013, and 38 in 2014.