Chances of exceeding the safe limit for the chemical are also exacerbated by reconstituting powdered infant formula with contaminated water, said the researchers in a study published last month in The Journal of Exposure Science and Environmental Epidemiology.
The infant formula industry in the US has dismissed the findings on the basis that the trace levels detected are “far below” safe reference values established by the Environmental Protection Agency (EPA).
Perchlorate is a chemical used since the 1940s in the production of solid propellants for rockets, missiles and aerospace missiles, which has led to the a flood of headlines in national press stating that infant formula is contaminated with a “jet fuel” chemical.
The soluble chemical has contaminated waste water, and from there has made its way into soil and water supplies. As a result, it has been absorbed by plants found in contaminated regions, and has been detected in fruit and vegetables and dairy products.
Range of products tested
Researchers from CDC’s National Center for Environmental Health tested around 15 brands of infant formula, which fell into four main categories: Cow’s milk-based with lactose; cow’s milk-based without lactose; soy milk-based; and elemental (made with synthetic amino acids).
The study did not reveal the names brands, but said that the two products found to contain the highest levels of the chemical made up 87 percent of the US powdered formula market, as measured by the US Department of Agriculture’s Economic Research Service in 2000.
The most heavily contaminated products were products made from cow’s milk, said the researchers led by Joshua Schier.
This is most likely linked to the capacity of the mammary gland to transport and concentrate iodine, with which perchlorate competes in the human body. It also means that the chemical could be transmitted to infants via breast milk.
Iodine is necessary for the production of thyroid hormones. Proper thyroid function, in turn, is vital for optimal neurological development in infants. Perchlorate inhibits iodine transportation within the body, effectively creating a state of iodine deficiency.
The US Food and Drug Administration requires that infant formulas are supplemented with iodine at levels between 5μg and 75μg per 100 kal of energy. This would likely lessen the potential of iodine deficiency and the possibility of perchlorate-induced thyroid dysfunction, said the researchers. However, they estimated that brands containing only minimum levels of iodine would leave infants more vulnerable to the toxic effects of perchlorate.
Detectable levels in all brands tested
In 2005, the Environmental Protection Agency adopted a daily reference dose for perchlorate of 0.7μg/kg per day.
The researchers of the current study reported that they identified detectable levels of perchlorate in all powdered infant formulas tested. In some cases, they found the potential contamination was in excess of the 0.7μg/kg limit.
In more than half of the cases, the limit could be exceeded by reconstituting the powdered infant formula (PIF) with water than was contaminated with at least 4μg/l of perchlorate.
The results are in line with the findings of a previous study (Pearce et al. – 2007) which found perchlorate levels ranging from 0.2-4.1μg/l in 14 samples of milk-based formulas, and 0.3-0.4μg/l in three soy-based samples.
“Perchlorate was found in all brands and types of infant formula tested. All bovine milk-based PIFs with lactose have significantly higher concentrations of perchlorate than the other three types tested (soy-based, lactose-free, and elemental),” wrote the researchers.
“Infants consuming certain bovine milk-based PIFs with lactose may be at risk for exceeding the RfD (0.7 mg/ kg per day). Reconstitution of PIFs with water containing perchlorate levels of at least 4 mg/l resulted in 26/48 (54 percent) hypothetical dosing scenarios exceeding the RfD. Ingestion of PIFs that use water with even minimal amounts of perchlorate for reconstitution could result in a perchlorate dose that exceeds the RfD in many cases.”
The researchers said further work is necessary to determine the risk of exceeding the perchlorate limit in both iodine-sufficient and iodine-deficient states.
Tomorrow, NutraIngredients-USA.com will report on responses to the study.
Perchlorate exposure from infant formula and comparisons with the perchlorate reference dose
Journal of Exposure Science and Environmental Epidemiology (18 March 2009), 1–7
Authors : Joshua G Schier, Amy F Wolkin, Lisa Valentin-Blasini, Martin G Belson, Stephanie M Kieszak, Carol S Rubin, Benjamin C Blount