The European Food Safety Authority (EFSA) has published a scientific opinion calling chronic dietary exposure to perchlorate a potential concern, “in particular for the high consumers in younger age groups of the population with mild to moderate iodine deficiency.” In addition to considering scientific literature on perchlorate levels in fruit juices, alcohol beverages, milk, and infant formula and breast milk, EFSA’s Panel on Contaminants in the Food Chain (CONTAM) analyzed 4,731 fruit and vegetable samples to estimate chronic and short-term exposure to perchlorate in the food chain. The report also identified several contamination sources, including natural fertilizers, industrial emissions and chlorine-based products that degrade to perchlorate.

According to the CONTAM Panel, which found the highest mean perchlorate concentrations in leafy vegetables and herbs, the average chronic dietary exposure for adults ranged from a minimum lower bound (LB) of 0.03 μg/kg body weight (bw) per day to a maximum upper bound (UB) of .13 μg/kg bw per day. The average chronic dietary exposure for toddlers ranged “from 0.18 to 0.41 μg/kg bw per day (minimum LB-maximum UB),” while the exposure for infants was calculated at 0.14-0.20 (LB-UB) and 0.47-0.53 (LB-UB) μg/kg bw per day, based on the only two consumption studies available for this age group.

Noting that perchlorate “competitively inhibits the uptake of iodine” in the human thyroid, the CONTAM Panel concluded that “the chronic adaptive changes to compensate for a sustained inhibition of thyroid iodine uptake could lead to long term effects such as the development of multinodular toxic goiter, in particular in populations with mild to moderate iodine deficiency.” The report also warned that short-term exposure “is of concern for breast-fed infants and small children with low iodine intake.”

“The CONTAM Panel recommended that more data should be collected on the occurrence of perchlorate in food in Europe, especially for vegetables, infant formula, and milk and dairy products,” states the scientific opinion. “The CONTAM Panel identified the need for biomonitoring data for perchlorate and the associated iodine status in Europe, including data on urine and breast milk, and noted that additional data on the level and duration of thyroid iodine uptake inhibition that has an impact on thyroid hormone levels in the vulnerable subpopulation groups would improve the risk assessment.”