What's in your water bottle besides water?

A reader writes The Green Guide:

I just read your article on plastic bottles. The article says to avoid #7 plastic because the polycarbonate contains bisphenol-A. I had been under the impression that the Nalgene bottles made of #7 plastic were the safest plastic bottle. I had been told that the bottles were made of "medical-grade" plastic and did not leach any chemicals. Are all #7 plastics polycarbonate? I have been using these water bottles during my entire pregnancy, because they were supposed to be "safe". I'm alarmed by your report and would appreciate any info you can provide. Thanks.

Sheri Sheibani

The Green Guide responds:

Not all #7 plastic is polycarbonate, nor are all Nalgene bottles made from polycarbonate. Unlike #1-#6,#7 is the official "other" plastics category. Nalgene makes several varieties of water bottle, made from different kinds of plastic, including polyethylene and polypropylene. Nalgene's Lexan bottles are made of polycarbonate plastic (PC), a plastic known to leach the hormone-disrupting chemical bisphenol-A (BPA). This puts it in the company of two other plastics which studies have determined are prone to leaching and pose environmental and/or health concerns: 1) Polyvinyl Chloride (PVC) which can leaches phthalates, a hormone disruptor, and dioxin, a carcinogen; and 2) polystyrene, which can leach styrene, a possible human carcinogen.

Does that mean Nalgene Lexan water bottles are unsafe? We cannot say categorically that Nalgene Lexan bottles are unsafe or even that they leach BPA, until the product has been properly tested. According to Our Stolen Future: "No tests on bisphenol-A leaching have been carried out specifically on Nalgene water bottles, to the knowledge of www.OurstolenFuture.org, nor were Nalgene bottles the brand used in the experiments demonstrating a link between polycarbonate and chromosomal aberrations. There may be some reason why Nalgene bottles do not leach bisphenol-A. This would be highly unexpected, however, given their chemical composition."

What We Know

PC is a durable and heat resistant plastic, making it a popular material for food storage and laboratory equipment, including baby bottles, water bottles, petri dishes and animal cages. In the late 1990s, studies testing PC baby bottles found they leached low levels of BPA. After several tests of the same bottles the presence of BPA decreased dramatically. The studies suggested that while residual amounts of BPA may be present on some baby bottles, it would disappear after a short period of use. The studies concluded that the PC baby bottles currently on the market are not a health risk to children.

In 2003, a study, published in Environmental Health Perspectives (EHP), reproduced the same results as the earlier studies when new bottles were tested. However, after repeated washings and scrubbings, the levels of BPA leaching from the bottles increased significantly. The study concludes, "The increased migration levels may be due to polymer degradation."

During the same year, two more studies were published in EHP, which came about after researchers traced BPA in lab mice to the PC cages in which the mice were housed. These studies share several of the same conclusions: 1) Polycarbonate exposed to harsh detergent is prone to leaching; 2) The older the polycarbonate, the more it leaches; 3) High temperatures cause higher rates of leaching. One study found that polycarbonate will leach into water at room temperature. Of even greater concern, the laboratory plastics studies were initiated by sudden abnormalities in mice egg cells after polycarbonate animal cages were mistakenly washed with the wrong detergent.

Erring on the Side of Caution

Until all of the facts are in, we recommend stainless steel water bottles, such as Klean Kanteen and polypropylene bottles such as Rubbermaid's Chuggables listed in The Green Guide Plastics for Kitchen Use report. Stainless steel bottles should have a metal cap as well. Aluminum bottles with an enamel inner coating are also a healthy alternative, though aluminum requires more energy to produce and has greater environmental impact than stainless steel. The Swiss Sigg bottle is made from extruded aluminum and coated on the inside with a taste-inert, food-compatible stove enamel.

If you're still attached to your Nalgene water bottle, you can lower any potential health risk by following a few common sense guidelines. Based on what we know from the current research, PC is most likely to leach BPA during it initial use and after prolonged use. Heat increases the likelihood of leaching as well. It makes sense, then, to replace your bottle every six months or whenever it appears worn. When you buy a new bottle wash it out with warm water and a mild detergent and let it dry at room temperature. Do not wash your bottle in the dish machine or leave it for prolonged periods in direct sunlight. Only use the bottle to carry cold water; don't fill it with hot water or other liquids. While it is important to keep the bottle clean and bacteria-free, avoid strong detergents and bleach as they can facilitate leaching.

This is an unfolding story, and The Green Guide will be following all related studies as they become available to us. We will continue to keep our readers updated on this important issue.

Resources
Stainless steel water bottles with stainless steel caps:
Klean Kanteen w/ cap 27 fluid ounces $21.00
emagazine.greenhome.com

Stainless steel thermos:
MLS Stainless Steel Thermos Bottle
1 liter $23.95
mls-group.com

Nissan Thermos
34 ounces $34.99
coffee-makers-espresso-machines.com

Enamel coated aluminum bottles:
Sigg, 1 liter $15.95
www.sigg.ch/

Polypropylene bottles:
Platypus Play Sport collapsible water bottle
.5 liter $4.50
www.rei.com

Nalgene Silo
48 ounces $9.25
www.rei.com

For more, see The Green Guide's Plastics for Kitchen Use product report