The Facts About Styrene, Cancer and Bike Helmets

bike helmet and coffee cup photo

Image: Flickr, Roland

In spite of budget problems, and on the heels of listing marijuana smoke as a carcinogen, the California Office of Environmental Health Hazard Assessment now girds for battle with the styrene industry. California has proposed to list styrene monomer as a carcinogen under the law known as "Prop 65". The industry has filed suit to stop the listing. And using a technique we thought most publicity firms had unlearned as long ago as the 1980's, the industry attempts to preempt our coverage with a reactionary, defensive and downright insulting statement:

News media looking for an alarming headline and organizations promoting themselves as advisers on 'green living' or 'environmental watchdogs' will claim there is a 'known carcinogen' in take-out food containers, bike helmets, egg cartons and berry baskets ... Styrene will permanently lose public confidence and market share.

I invite the styrene industry to consider that sustainable living is about knowing the costs and risks of products we use, and balancing them in favor of avoiding undesirable outcomes from living an unexamined life. Products should have public confidence because the public knows the facts are being examined in a transparent manner, not because we should mindlessly prop up market share at all costs. So let us look at the facts.

Fact 1: This is Not News
The potential for low levels of chemicals to migrate from polystyrene, and even be detected as an off-flavor, has long been established. These chemicals include both styrene (monomer), as well as an intermediate in styrene manufacture, ethylbenzene. Ethylbenzene has been listed as a carcinogen in Prop 65 since June 11, 2004.

Styrene has been listed by the World Health Organization's International Agency for Research on Cancer (IARC) since 1987 as group 2B, "possibly carcinogenic to humans." IARC reaffirmed that decision in further reviews in 1994 and 2002. (IARC did not rank styrene in the more severe levels: group 1 "carcinogenic to humans" or group 2A "probably carcinogenic to humans.")

Fact 2: Styrene May be a Carcinogen but Not Cause a Risk
IARC ranked styrene as a possible carcinogen based on studies of the health of people who worked in styrene-related manufacturing operations. The data dates back to an era of older engineering measures to protect worker health. In modern manufacturing operations, workers face much lower exposures and the link between the chemical and an illness is no longer apparent. That means workers are currently NOT getting cancer at a rate higher than the general population, but IARC wants more evidence before they drop the carcinogen rating. After all, it is the evidence of a possible link that justifies action (and the expense) to protect worker health.

Fact 3: Styrene Does Not Accumulate in Humans or the Environment
Styrene degrades rapidly. It does not hang around in the environment and does not build up in the food chain. Thus there is little likelihood of the general public reaching unacceptably high levels of exposure.

Fact 4: Food Clamshells, Egg Cartons, and Bike Helmets are not Styrene
The chemical in these everyday products is polystyrene. Polystyrene is a bunch of styrene monomers linked together in long chains. These long chains are too big to be available in your body at the level of the mechanisms responsible for causing cancers. Polystyrene is a very safe plastic. It is recyclable, with the downside that it is very light and therefore rarely enters post-consumer recycling because it is uneconomical to collect. It is widely recycled at high rates in pre-consumer (industrial) loops, and remains harmless in landfills forever. Unfortunately, it also remains as litter forever, and polystyrene has a black smirch on its reputation for destroying the natural beauty of shorelines and interfering with wildlife.

What Should You Conclude?
Your risk of brain injury in a bike accident vastly outweighs the risk of cancer from that helmet. You are well-advised to choose to wear a helmet.

Polystyrene insulates. Lightweight plastics contribute to efficient transportation. The energy saved by using polystyrene reduces your exposure to risks from energy production, probably more than the risk of cancer from styrene. Until better alternatives such as bio-plastics are viable, polystyrene benefits can justify some risks.

But styrene uses petroleum feedstock and energy in production. Post-consumer recycling is inefficient. And residual styrene monomer is migrating into the cream of chicken soup you nuke in a polystyrene cup. The industry should not use the fact that other food-use disposables may have worse hidden risks as a defense. The best choice is a re-usable cup or bowl over the disposable foam.

Are you listening, styrene industry? Disposable market share is unsustainable. Let us stop worrying about market share and find something more constructive to merit the investment of resources into this useful and beneficial application of modern chemistry. Use the money you are wasting in a lawsuit for life cycle analysis of the best paths forward for your product and control technologies to ensure that any risks remain low. And trust the pubic. We are not as dumb as you think.

More on Styrene and Prop 65:
Sacramento Bee, Styrene industry sues to halt California Prop. 65 cancer listing
California Proposes Listing of 30 Chemicals as Causing Cancer or Reproductive Harm
San Francisco Bans Styrofoam for To-Go Containers

The Facts About Styrene, Cancer and Bike Helmets
In spite of budget problems, and on the heels of listing marijuana smoke as a carcinogen, the California Office of Environmental Health Hazard Assessment now girds for battle with the styrene industry. California has proposed to

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