For Patients and Families

In this interview, Michael Shannon, MD, MPH, a pharmacologist/toxicologist and chair of Children's Division of Emergency Medicine, discusses the current controversy and gives parents advice on the safety of plastic baby bottles.

Bisphenol-A and phthalates are two types of chemicals that have really reached the public's attention in recent days because of two reasons. One, they seem to be found in several products that are used in babies, young children. And two, because there is growing evidence that they may have affects on the human body.

I think what's probably received the most attention in recent days is they're being found in baby bottles and in the plastic linings that we sometimes put formula in. There's significant difference in the type of bottle and what it might contain and I actually have some examples here with me.

The so called clear, hard plastic bottles, this is a material known as polycarbonate, tends to have BPA in it, some amount of Bisphenol-A in it. Whereas the plastic bottles or the plastic liners may have phthalates in them rather than Bisphenol-A. [Thus] two types of baby products each containing a different type of substance.

The best way to describe the type of effects that Bisphenol-A and phthalates have is to first consider they belong to a large group of chemicals that are known as endocrine disruptors. Endocrine disruptors are chemicals that seem to be able to mimic the effect of our bodies' own hormones. There is a potential for taking in a substance, taking in a chemical that starts to change how your body is functioning. Both Bisphenol-A (which we'll call BPA) and phthalates belong to this long class called endocrine disruptors.

In terms of the types of effects that these chemicals could produce as endocrine disruptors the first thing I would emphasize is we have no evidence that they have produced those effects in babies or in humans, for that matter. The concern has relied primarily on experimental data and experimental models but it does seem that in these experimental models that the BPA that's in polycarbonate bottles seems to act like a synthetic estrogen and the phthalates found in plastic seem to act as what are known as anti-androgens, chemicals that would block the effect of testosterone the male hormone. Again, in an experimental setting we can see that effect, in humans we have not seen it yet, but that is the cause for concern.

An obvious question is how it is that placing formula or breast milk in a bottle or storing it in a bottle lead to a chemical that's in a bottle getting into that formula or breast milk. The term we use is leeching. Leeching is very common; whenever the liquid or food comes into contact with the chemicals that make up that lining, that interior, have the possibility of escaping the can or bottle and migrating into the formula or breast milk. That's a phenomena we call leeching. And we do know that for both polycarbonate bottles and plastic bottles that some amount of leeching of BPA and phthalates occurs.

We also know that when you heat these products, when you heat a polycarbonate bottle or heat a plastic bottle, there's even greater leeching. Even before we knew the exact chemicals that were in these bottles and even thought they were harmful, the teaching was not to heat formula or breast milk while they are actually contained in these bottles, because the heat will increase the leeching.

Updated April 22, 2008

Recently, a report by the National Toxicology Program has suggested there is "some concern" about the effects of BPA in children. While their conclusions were based primarily based on experimental studies, they further support the recommendation to limit infant's exposure to BPA where possible.

Well, there are definitely options for parents that would just like to take the extra step in reducing their child's exposure to these chemicals.

For example, rather than polycarbonate or plastic bottles, a parent could choose to use glass. Glass is certainly more durable and it does not have these chemicals in it. However, glass is a little heavier, a little harder to work with, it breaks unlike these substances. I think the other thing a parent could do if really interested in minimizing exposure to these chemicals is thinking carefully about how they are going to store their formula or breast milk, for that matter. If possible, it would be better to keep formula or breast milk in a glass bottle vs. a polycarbonate or a plastic bottle. And that's just going to reduce some of the exposure.

Updated April 22, 2008

Research in this area will undoubtedly continue. It is possible that concern about these products, both by researchers and consumer advocates, could lead to a voluntary reduction in their use.