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Storing Baby’s Milk
Healthy Child Healthy World
Wednesday, April 04, 2007
Chances are, whether you bottle feed your baby or nurse her, there will be times when you need to store her infant formula or breastmilk. It turns out that glass may be the best material for storage.
Researchers have found that polycarbonate plastics ( recycling symbol #7) can leach bisphenol-A under certain conditions, including the heating of infant formula and breast milk.1 Similarly, containers made of PVC plastic can leach other suspected endocrine disruptors, phthalates.2
In addition, studies published in Early Human Development and Nutrition Review show that milk stored in some plastics, such as polyethylene and polypropylene containers, may lose some nutrients because they cling to the plastic.
Polyethylene bags, such as those used in disposable bottle systems, have not been shown to leach toxic chemicals to date. If you do use polyethylene bags to freeze milk, be careful when filling. Some of these bags are difficult to handle. And inspect them before you pour the breastmilk in and when you defrost it — plastic bags may split at seams or tear, increasing the chances of bacterial contamination.
Safest options include wide-mouth glass canning jars, which are made of heavy glass that can withstand cold and heat. They come in one-cup (eight ounce) sizes. Filling the jar halfway means you can leave room for expansion so the glass won’t crack. These jars won’t screw onto breast pumps, but you can just pour the milk into them (fairly easily since they are have wide mouths).
The most environmentally friendly option is to wash and reuse other glass food containers—things like jam jars and baby food jars (for those babies that are “snacky” eaters and rarely have more than a few ounces at a time). Just be sure you’ve washed the jar and lid in very hot, sudsy water to ensure your baby’s milk doesn’t end up tasting like the food that was previously in the jar.
Whether you choose glass or plastic, remember to inspect storage containers frequently. Scratches in plastic containers can hide bacteria, which can contaminate formula or breastmilk. And glass can chip or crack.
1 Howdeshell KL, Peterman PH, Judy BM et al. 2003. Environmental Health Perspectives 111(9): 1180-87.13.
2 Silver, LB, M.D. Practice Prevention: Plastics. Institute for Children’s Environmental Health Learning and Developmental Disabilities Initiative, 2006.
