3 Steps to Take If #5 Plastic Leaching Has You Worried

Annie B. Bond by Annie B. Bond | February 4th, 2009 | 2 Comments
topic: Detox, Green Living, Health & Wellness, Healthy Eating

poly5When I think of plastic #5 — polypropylene, commonly used for yogurt containers, syrup bottles, ketchup bottles, caps, straws and medicine bottles — I think of my mother going into a fit of recycling rage, ranting about the fact that we couldn’t recycle plastic #5 in our area. But the real story here parallels the BPA scare with water bottles and baby bottles

Some researchers think #5 plastic yogurt tubs may leach substances that aren’t fit for human consumption.

For years I thought containers made of plastic #5 were at least safer for our health than other plastics; polypropylene is not generally considered a plastic that may disrupt hormones, as are plastics #3, #6, and #7. But in the early 90s, researchers at Tufts University were mystified when they found that the hormone estrogen kept popping up in their petri dishes during experiments that didn’t involve estrogen. They kept repeating the experiments, and kept finding estrogen. Finally, an inquisitive researcher started looking at the plastic tubing distributing the materials into the petri dish, and on testing the plastic, found an estrogenic chemical leaching from the plastic.

This simple discovery led to the groundbreaking book Our Stolen Future, about how some plastics and other hormone-disrupting chemicals are causing endocrine disruption in wildlife. The research profoundly changed the way we look at products from a health perspective.

Then recently, researchers at the University of Alberta found chemicals leaking from their plastic laboratory equipment. (Beginning to sound familiar?) The equipment was made of polypropylene. The leaching chemicals were surprisingly biologically active and drew the focused attention of the researchers. One of the chemicals that leached from the polypropylene is oleamide, a chemical found naturally in the brain. Could adding a synthetic oleamide to our brains negatively affect brain health? Nobody knows.

3 things you can do if you’re concerned about #5 plastic’s safety

1. Lean toward the precautionary principle. It might not be smart to eat yogurt from a #5 plastic tub every day. And while manufacturers favor #5 because this strong, light plastic uses 30 percent less plastic than heavier plastics, some other foods commonly packaged in #5 plastic are often also available in glass or other containers.

2. Write to your favorite food brands and ask for alternatives. The organic yogurt company Stonyfield Farms explains on its website that “There are several very promising materials on the horizon. We are working with one supplier of a plastic made from carbohydrates, such as corn and beets. In the not too distant future, your yogurt cup could look and feel like the plastic cup of today, but be made from excess agricultural materials such as cornhusks or potato skins.”

3. Consider making your own yogurt. There are a number of yogurt making appliances on the market. Check out the models that might work for you with this handy comparison chart. Once you get started you’ll be amazed at how many recipes are available on the internet for using yogurt, including how to make it from scratch.


  1. Dear Ms. Bond,

    I worked for Waterwise in Florida and found your blog while searching for information on polypropylene. We have been looking for the study from the University of Alberta and/or any articles that may coincide with this study. Would you have any available information that you would be able to share with us? Anything you have available would be extremely helpful.

    Thank you.

    Kelli Weaver | October 30th, 2009 | Comment Permalink
  2. This doesn’t sound like much of a threat. Oleamide, a chemical already found naturally in the brain? How does its synthetic origin matter? It’s the same substance, right? What does “surprisingly biologically active” mean, exactly? Are there any studies showing actual harm?

    Wordwizard | August 23rd, 2012 | Comment Permalink

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