Plastic Polymers and Food Safety

When plastics are recycled, the various types must be separated from one another. To aid in the separation, many states require manufacturers to include a recycling symbol on their products to indicate the type of plastic. 

You are probably familiar with these symbols, wich are found on the bottom of plastic containers. The symbols consist of three arrows around one of seven numbers; an abbreviation below the symbol indicates the type of polymer from wich the container is made. 

The lower the number in the middle of the symbol,the greater is the ease with wich the material can be recycled: 1 (PET) stands for poly ( ethylene terephthalate), 2(HDPE) for high-density polyethylene, 3(V) for poly ( vinyl chloride ), 4 (LDPE) for low-density polyethylene, 5 (PP) for polypropylene, 6 (PS) for polystyrene, and 7 for all other plastics.

Plastic Container Symbols for Food Grade Plastics

Types of Plastics and Food Safety By Plastic Number

Please reference Graphics for Quick View of Numbers to look for embedded into plastic products to help determine their safety.

1. PETE: Polyethylene terephthalate ethylene, used forsoft drink, juice, water, detergent, cleaner and peanutbutter containers.

2. HDPE: High density polyethylene, used in opaque plastic milk and water jugs, bleach, detergent and shampoo bottles, and some plastic bags.

3. PVC or V: Polyvinyl chloride, used for cling wrap, plastic squeeze bottles, cooking oil and peanut butter containers, and detergent and window cleaner bottles.

4. LDPE: Low density polyethylene, used in grocery store bags, most plastic wraps, Ziplock bags and some bottles.

5. PP: Polypropylene, used in most Rubbermaid, deli soup, syrup and yogurt containers, straws and other clouded plastic containers, including baby bottles.

6. PS: Polystyrene, used in styrofoam food trays, egg cartons, disposable cups and bowls, carry-out containers and opaque plastic cutlery.

7. Other: This is a catch-all category for plastics that don’t fit into the #1-6 categories. It includes polycarbonate, bio-based plastics, co-polyester, acrylic, polyamide and plastic mixtures like styrene-acrylonitrile resin (SAN). Number 7 plastics are used for a variety of products like baby bottles and “sippy” cups, baby food jars, 5-gallon water bottles, “sport” water bottles, plastic dinnerware and clear plastic cutlery.

What to look for on Plastic Containers

Here are some things to keep in mind when using the microwave:

• Most takeout containers, water bottles, and plastic tubs or jars made to hold margarine, yogurt, whipped topping, and foods such as cream cheese, mayonnaise, and mustard are not microwave-safe.
• Microwavable takeout dinner trays are formulated for one-time use only and will say so on the package.
• Don’t microwave plastic storage bags or plastic bags from the grocery store.
• Before microwaving food, be sure to vent the container: Leave the lid ajar, or lift the edge of the cover.
• Don’t allow plastic wrap to touch food during microwaving because it may melt. Wax paper, kitchen parchment paper, or white paper towels are alternatives.
• If you’re concerned about plastic wraps or containers in the microwave, transfer food to glass or ceramic containers labeled for microwave oven use.

Source:  Harvard Health Publications

Our homes are full of plastic, and the kitchen is no exception. The problem: Chemicals in plastic containers and other kitchenware may leach into the foods or drinks that they’re holding. Scientific evidence suggests that some of these chemicals may be harmful to people, especially infants and children.

The two best-studied offenders are bisphenol A (BPA) and phthalates. BPA mimics estrogen and has been shown to disrupt hormone and reproductive system function in animals. Research by the National Toxicology Program found a moderate level of concern about its “effects on the brain, behavior and prostate gland in fetuses, infants and children.” Phthalates have been shown to disrupt the endocrine system and have led to malformations in the male reproductive system in animals. Studies in humans have found associations between high phthalate exposure and a variety of health concerns including low sperm quality, high waist circumference and insulin resistance.

Researchers are still debating whether phthalates and BPA actually cause these health problems and, if so, how much exposure is necessary to trigger them. While these issues are being figured out, some experts recommend taking a preventive approach: “Minimize contact of food with problematic plastics as a precautionary measure to protect your health,” suggests Rolf Halden, PhD, adjunct associate professor of environmental health sciences at the Johns Hopkins Bloomberg School of Public Health. Here are six simple tips for reducing your exposure to the potentially harmful chemicals in plastics.

1. Know the code. Look on the bottom of your plastic to find the recycling symbol (a number between 1 and 7 enclosed in a triangle of arrows). The code indicates the type of plastic you are using and can give you important clues about safety. “We generally say 1, 2, 4 and 5 are considered to be the safest,” says Sonya Lunder, senior analyst at the Environmental Working Group. Try to avoid using plastics with 3 or 6, as these leach chemicals that may be harmful. Number 7 is an “other” category that includes BPA-containing plastics called polycarbonates. These plastics, which you should avoid, will have the letters PC printed underneath the 7.

2. Reconsider the microwave. Heat can increase the rate at which chemicals like BPA leach from plastic. Containers labeled “microwave safe” have been tested by the Food and Drug Administration (FDA) and found to leach extremely small amounts, which the FDA has determined to be safe. However, some experts advise people to keep plastic out of the microwave altogether. “I don’t microwave anything in plastic,” says Lunder. “It’s really easy and fast to put my food into a ceramic or glass container and heat it that way.” And never put plastic wrap on top of your food in the microwave, since it can melt. Use wax paper or a paper towel instead.

3. Use it for its intended purpose. Plastics that are designed for single use should only be used once. “Plastic breaks down over time,” Lunder explains. “Some aren’t designed to withstand heating and cooling.” Most plastics with recycling code number 1 are intended for single use, such as disposable water bottles. And that takeout container from six months ago? Toss it. In general they’re fine for refrigerating leftovers, but aren’t designed for heat exposure or long-term use.

4. Wash by hand. Only put plastics into the dishwasher if they have a dishwasher safe label. If you want to be extra-cautious, wash all plastics by hand or use only glass and ceramic plates and dishes. In the dishwasher, plastics are exposed to detergents and heat, which may accelerate the leaching of BPA from food containers.

5. Do not freeze. Only put plastics in the freezer if they have a freezer-safe label. Freezer temperatures can cause plastics to deteriorate, which increases the leaching of chemicals into the food when you take containers out of the freezer to thaw or reheat.

6. Don’t panic. Cutting down on exposure to potentially harmful chemicals in plastics can benefit your health. But as Dr. Halden reminds us, “Many things in your life pose a much higher risk than exposure to plastics, such as smoking, poor diet and even driving a car.”

Ref; 

Essentia Organic Chemistry, Paula Y. Bruice 

Spine Health, Plastic Container Safety – Understanding Plastic Labeling Numbers