Writing in The FASEB Journal, researchers used a rat model to investigate how perinatal exposure to low doses of BPA affected immune-related food intolerances in later life of the offspring.
Led by Sandrine Menard of INRA in France, the team tested the effect of exposure to BPA in the period immediately before and after birth of pups (known as perinatal exposure) on immune-specific response to the food antigen ovalbumin (OVA) in adult offspring – finding that such exposure altered oral tolerance and immunisation to the dietary antigen.
“In summary, the naive immune system of neonate is vulnerable to low doses of BPA that trigger food intolerance later in life,” concluded the Mernard and her colleagues – noting that the findings support the decision made French authorities to ban the use of BPA in containers used for infant foods as early as 2013, and in all food packaging as from 2015.
However, the team conceded that the results of rat study cannot be directly translated to humans – noting that further research must now be done.
Reacting to the release of the study the BPA Coalition, a Brussels-based association of manufacturers and users of Bisphenol-A, said BPA-based products have been proven over and over again to be safe for human consumption and warned that the INRA study has “a number of flaws.”
“In recent years at least 20 major government assessments have been undertaken by independent authorities across the world on BPA, all of which found that BPA did not pose a risk to human health. Furthermore, regulators are continuing to examine the safety of BPA on an ongoing basis. The weight of scientific evidence provided clearly supports the safety of BPA-based applications,” it said.
However, the French research team cautioned that the potential risks to consumers of BPA, which is mainly found in food packaging materials, has been the subject of several, sometimes contradictory, reports from international health agencies during the past five years.
In April 2013, the French Agency for Food, Environmental and Occupational Health and Safety (ANSES) published an opinion on bisphenol A which recommended limiting exposure to this substance and lowering the toxicological thresholds on which risk evaluations were based. Shortly after the French decision, the European Food Safety Agency (EFSA) also proposed applying a new BPA limit value that was ten times lower than previously, or 5 µg/kg body weight/day.
During their work, the INRA researchers used two groups of gestating rats. One group received a daily oral dose of BPA of up to 5 μg/kg body weight, from gestation until the weaning of newborns at 21 days, while the other (control) group did not receive any BPA. The newborns from these two groups were then studied.
In adulthood, or at the age of 45 days, the animals were fed with the egg white protein ovalbumin - which had not previously been included in their diet. The researchers then looked out for any immune reaction directed against ovalbumin among the animals.
Rats descending from the control group developed a food tolerance of ovalbumin, which resulted in a lack of immune responses, said the group. Meanwhile, those with parents that had been exposed to BPA showed an increase of anti-OVA IgG immune antigens – signalling an allergic reaction.
Furthermore, repeated oral administrations of ovalbumin in these rats induced colonic inflammation that often characterises food intolerance.
During this INRA study, the scientists tested different doses (0.5, 5 and 50 μg/kg body weight/day) and demonstrated a non-linear relationship between the BPA doses and the undesirable effects observed. In particular, the most marked disturbances were observed at a dose of 5 μg/kg body weight/day, or in other words the dose considered by the EFSA to be risk-free in humans.
“These findings have therefore highlighted the problem of determining a safe and tolerable daily dose for BPA,” said the researchers.
Source: The FASEB Journal
Published online ahead of print, doi: 10.1096/fj.14-255380
“Food intolerance at adulthood after perinatal exposure to the endocrine disruptor bisphenol A”
Authors: Sandrine Menard , Laurence Guzylack-Piriou , et al