NEW YORK, Jan. 27 (AScribe Newswire) -- In a perfect world, the ideal plastic container would be non-petroleum-based, non-leaching, reusable and recyclable or biodegradable. But for the moment, most consumer plastics are made from a variety of petroleum-based resins, which are classified in the seven recycling codes seen in the triangle on the bottom of containers, as follows:
No. 1 -- polyethylene terephthalate (PET or PETE)
Products: Soft drink bottles, medicine containers.
No. 2 -- high density polyethylene (HDPE)
Products: Milk and water bottles, detergent, shampoo and motor oil bottles.
No. 3 -- polyvinyl chloride (V or PVC)
Products: Pipe, meat wrap, cooking oil bottles.
No. 4 -- low density polyethylene (LDPE)
Products: Wrapping films, grocery bags.
No. 5 -- polypropylene (PP)
Products: Syrup bottles, yogurt tubs, diapers.
No. 6 -- polystyrene (PS)
Products: Coffee cups, take-out containers.
No. 7 -- other (usually polycarbonate)
Products: Medical storage containers, Nalgene water bottles.
A new generation of polyactide (PLA) plastics made from corn rather than petroleum may improve the situation. PLA is biodegradable, and, commercially, PLA single-use food containers and plastic wraps are now available. While we wait for these plastics to become more widely available, we must settle for a handful of relatively non-leaching, reusable and recyclable products. No. 2 high density polyethylene (HDPE) plastics are both durable and recyclable through most curbside recycling programs. Studies have shown HDPE is capable of low-level leaching under extreme conditions not typical of normal home use. Unfortunately, few reusable no. 2 storage containers are available. More common but less recyclable are reusable containers made from no. 5 polypropylene (PP) plastic. Studies so far indicate that PP is even less prone to leaching than HDPE.
PET (or PETE) containers are generally considered the safest single-use plastic bottle choice. Most store-bought drinks are packaged in PET containers, and they are accepted by most curbside recycling programs. An Italian study from 2003 showed that the amount of DEHP, an endoctrine-disrupting phthalate and a probable human carcinogen, in bottled spring water was found to increase after 9 months of storage in a PET bottle. It is unclear whether the levels detected could harm people drinking the water. Until further research clarifies the risk of PET containers leaching DEHP, we recommend that products packaged in PET containers not be stored for long periods of time and that the containers not be reused.
Polycarbonate plastics, those in the no. 7 bottle, contain bisphenol-A, a known hormone disruptor which can dissolve into water. This is no small matter, since hormone disruptors are chemicals that interfere with the way hormones guide fetal development and later growth. As reported in Current Biology April 1, 2003, bisphenol-A exposure in pregnant mice resulted in errors in fetal cell division, though researchers caution that the same may not happen in humans. In fact, the most popular water bottle sold at REI is a Nalgene bottle made of the polycarbonate Lexan. According to the Our Stolen Future website, Lexan may be chemically different from standard polycarbonate plastic and less subject to leaching, though they have no evidence for this. Leaching of bisphenol-A increases with the plastic's age and when subject to heat.
Unfortunately, other plastics also leach toxins, or produce them in their manufacture or disposal. It's long been known that production of no. 3 PVC vinyl releases carcinogenic dioxins into the environment and no. 6 polystyrene can leach styrene, a possible human carcinogen which may also disrupt hormones.
All plastics breakdown under extreme conditions. As a rule of thumb, then, do not subject even the most durable plastic containers to high temperatures (microwave or dish machine); do not use them to store foods with high fat or oil content; and do not use containers that appear old, stained or worn. And the sniff test doesn't hurt: If you can smell or taste the plastic in a bottle, toss it in the recycling bin and get yourself a new one. "Microwave-safe" or "microwavable" containers can promise not to melt when heated, but they can make no such claims about leaching chemicals into your food. The Food and Drug Administration (FDA) has set standards for acceptable levels of chemical "migration" from plastics to food. These levels vary, depending on the believed toxicity of each chemical. In many cases, the ultimate effect of these chemicals is still unknown, so if the choice is between microwavable plastic or glass and ceramic, erring on the side of caution isn't such a bad idea.
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This article by Vincent Standley appeared on thegreenguide.com (February 26th, 2006). It is available for reprint on the web or in newspapers or magazines with credit to the Green Guide Institute.
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