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Natural Awakenings Metro Phoenix & Northern Arizona

The Effect of Plastics on Health: Dr. Krystine Nguyen of Arizona Center for Advanced Medicine shares which plastics are considered safe and which may be harmful to our health

Sep 30, 2013 07:58AM ● By Krystine Nguyen, NMD

The numbers one through seven printed on the bottom of a plastic bottle or container reflect seven different types of plastic available in the market and indicate which are recyclable. Those numbers can also tell us which plastics are considered safe and which are harmful to our health.

Most plastics contain chemical additives such as phthalates (plastic softeners) and bisphenol-A (BPA) to make them durable, flexible, soft, hard or resistant to UV light, according to their intended use. These two additives are known to be harmful, potent hormone disruptors, causing adverse health effects in both men and women, and have been linked to cancer, heart disease, diabetes, reproductive system damages and changes in the brain and behavior.

Plastic chemicals often leach into the food and water they contain. We don’t know much about the other additives, because the toxicity of plastics is not fully understood or been adequately tested. Plastics are ubiquitous, so avoiding plastics altogether might not be practical, but there are ways to limit our exposure to these toxins by becoming familiar with these numbers and using glass or other alternatives instead of plastics whenever possible. Also, it is best not to expose the plastics to heat sources such as the sun, microwave or dishwasher, because high temperatures can cause chemicals to leach out of the plastics.

Plastic #1: Polyethylene terephthalate (PET/PETE) is used to make bottles for juice, mouthwash, soft drinks/sport drinks, water, salad dressing, ketchup, jelly/jam and peanut butter. It is intended for one-time use only because its porous surface allows bacteria to accumulate. Antimony leaches out from water bottles when exposed to heat for prolonged time.

Plastic #2: High-density polyethylene (HDPE) is a hard, opaque plastic with low risk for leaching; it is used in milk jugs, water and juice bottles, toiletries and detergent bottles, and certain toys. There are no known health concerns documented.

Plastic #3: Polyvinyl chloride (PVC) is mixed with phthalates to make it soft and flexible. It is used to make cling wrap, deli and meat wrap, shower curtains, inflatable structures, waterbeds and pool toys. It is also used in car interiors and vinyl flooring, resulting in the release of toxic chemicals into the air. Harmful byproducts of PVC are often found in grasslands, where they are consumed by livestock and thus accumulated in meat and dairy products. Health effects are genetic changes, cancer, suppressed immune function and disruption of hormones, birth defects, learning and behavioral problems in children.

Plastic #4: Low-density polyethylene (LDPE) is a translucent or opaque, flexible and tough, but breakable, plastic. It is used in juice and milk cartons, bread, frozen food and grocery bags. There are no known health concerns documented.

Plastic #5: Polypropylene (PP) is intended for microwavable- and dishwasher-safe containers due to its strength, toughness, resistance to heat and moisture barrier qualities. It is also used in yogurt and margarine tubs, plastic cups, baby bottles, medicine bottles, straws and ketchup and syrup bottles. There are no known health concerns documented.

Plastic #6: Polystyrene (PS) is used to make hard plastic or Styrofoam products like disposable cutlery, CD/DVD cases, building insulation, egg cartons, foam cups and to-go foam packaging for restaurants. It is classified as a potential cancer-causing agent by the U.S. Environmental Protection Agency and by the International Agency for Research of Cancer. Long-term exposure can cause fatigue, nervousness, difficulty sleeping and genetic and blood abnormalities.

Plastic #7: Other (everything else) may or may not contain BPA. It is used in electrical wiring, CD/DVD cases, baby bottles and three- and five-gallon reusable bottles. There are potential health concerns if it contains BPA.

In summary, plastics #2, #4 and #5 are considered safer. Plastic #1 is somewhat safe, but it should not be reused due to the risk of growing bacteria. Plastics #3, #6, #7 should be used with extreme caution, especially around food or drink, and the risk is more significant when heating food. Thus, containers marketed as microwavable- or dishwasher-safe means only that the plastics will not melt. It does not mean that they are safe or healthy to use. In general, it is best to use glass or look for BPA-free containers. Ideally, avoid microwaving plastics if at all possible.

Krystine Nguyen, NMD, MPH, RD, practices integrative medicine at the Arizona Center for Advanced Medicine, with a focus on treating patients with cancer and chronic diseases. For information, visit

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