The Danger of BPA Over Time

Bisphenol A (BPA) is a toxic substance that causes hormonal imbalance. It is found in some plasticware and could be taken in with food. In this study, the blood level of BPA was estimated after feeding mice with a single dose of BPA. It was then compared to the levels in mice that took in BPA through the diet. It was found that the maximum blood levels of BPA were reached at one hour and six hours, for oral dosage and diet groups respectively. It was also found that the relative BPA availability was more in the mice in the diet group.

BPA is used in the manufacture of plasticware, including feeding bottles. It was assumed to be nontoxic. The demand for BPA has increased over the years with no signs of reduction in its usage, although it was later found to be toxic. This chemical is almost detectable in all bodies of water, leading to animals and humans getting exposed to it to a greater extent. It is estimated that 90% of people in the United States have measurable levels of BPA. The diet could also be a potent source of BPA intake. Since the details about the human route of exposure to BPA are difficult to assess, they remain debatable. However, mice seem to be the appropriate animal models to study the effects of BPA. Most studies use mice that are given a large dose of BPA and then the outcome is measured. In this study, the mice were exposed to BPA in a manner similar to the way humans take in traces of this chemical from the diet.

* In this study, the experiments were performed on adult female mice.
* One group of mice was given a large oral dose of BPA. Each mouse was fed with a dose of 20 mg per kg of BPA of its body weight. The other group of mice received 100 mg of BPA in the diet.
* The blood levels of BPA were assessed at various intervals, starting from one hour after for a period of seven days.

* The maximum blood concentrations of BPA, in a 24-hour period were attained at 1 hour and 6 hours in the group that received an oral dose and the group that received the chemical in the diet, respectively.
* The maximum concentration (Cmax) for BPA-d6 (5 ng of deuterated 16-bisphenol A) during the first 24 hours was reached at 1 hour and 6 hours for oral bolus and diet groups, respectively.
* The availability of the compound was higher in the mice that were on a diet, rather than the mice that received a single dose.

Shortcomings/Next Steps
Subtle variations in the feeding habits of mice in both the groups could have caused differences in the blood levels of BPA. Though speculative, the true reasons for the increase in availability of this chemical on the intake with diet remain elusive. Thus, more studies should be performed to ascertain the reasons.

This was the first study to quantify the exposure and the amount of BPA in the blood of mice exposed to the same in the diet. It was found that the mice exposed to BPA by dietary consumption had a higher availability of the chemical than those that had a single dose. This data highlights the limitations of a single oral dose of BPA, which is the trend in most studies. The single doses of BPA may underestimate the extent of exposure and lead to inaccurate results. Hence, it is hence clear that humans may be able to eliminate large, yet single doses of BPA more easily than a constant chronic dose present in the diet.

For More Information:
Serum Bisphenol A Concentrations in Diet-Exposed Mice
Publication Journal: The Environmental Health Perspectives, June 2011
By Paizlee T Sieli; Eldin Jasarevic
From the University of Missouri, Columbia, Missouri

*FYI Living Lab Reports Are Summaries of the Original Research.

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