More Chemicals Added To HHS List Of Known or Suspected Carcinogens

As noted this morning in our post about formaldehyde, The Health And Human Services Report on Carcinogens lists two categories: agents, substances, mixtures, or exposures known to be a human carcinogen and reasonably anticipated to be a human carcinogen. Some are found in strange places, like the
Aristolochic Acids that are found in herbal medicines and are now known to be carcinogenic. Avoid them completely; here is a list of everything from weight loss formulae to allergy relief to chinese medicinals. Another herb that is reasonably anticipated to be carcinogenic is Riddelliine.

Of much more interest are the addition of "certain glass wool fibers" and styrene. These affect all of us in our daily lives.


The late punk rocker Poly Styrene from her album, Generation Indigo
Styrene is reasonably anticipated to be a human carcinogen. It is used in the production of polystyrene, and small amounts of it are believed to leach out of styrofoam cups and plates. But the real risk is to workers who work with reinforced plastics; that fiberglas smell is probably styrene. The National Toxicology Program notes:

Workers in certain occupations are potentially exposed to much higher levels of styrene than the general population. For example, workers who fabricate boats, car and truck parts, tanks, and bath tubs and shower stalls with glass fiber-reinforced polyester composite plastics, may breathe in high levels of styrene in the workplace. Workers may also absorb styrene through the skin. Exposures in the workplace have decreased over time.

But it is also released from building materials, tobacco smoke and laser printer/copiers; if you have a copier in your home it should be in a well ventilated area. And it is another reason not to use disposable styrofoam containers.

Download the NTP fact sheet here

image credit Anne Hornyak
Certain Glass Wool Fibers are also again a suspected carcinogen. Here, the NTP is being very circumspect and careful. They separate conventional insulation glass fibers from special purpose ones, and suggest that the general home insulation kind is not as much of a danger.

There are generally two categories of glass wool fibers that consumers might use: low-cost general-purpose fibers and premium special-purpose fibers. Most home and building insulation projects use general-purpose glass wool. Special-purpose glass fibers are used for applications, such as separating the negative and positive plates in a battery, and in high-efficiency air filters and aircraft, spacecraft, and acoustical insulation. In general, insulation fibers are less durable and less biopersistent than special-purpose fibers, and may be less likely to cause cancer than the more durable, more persistent special-purpose fibers.

Two decades ago the the National Toxicology Program listed fiberglass as "reasonably anticipated to be a human carcinogen" based on animal data. In 2001, the International Agency for Research on Cancer looked at all the studies and took it off the list of possible carcinogens, and concluded that there was not enough evidence to consider it a cancer risk. Now it is creeping back on. Although the NTP is specifically excluding conventional insulation in their listing, they tested it and it did not come up totally clean:

Types of insulation glass wool fibers tested in experimental animals included Owens-Corning glass wool, MMVF 10 and 10a (both of which represent the respirable fraction of Manville 901 glass fiber), MMVF 11 (the respirable fraction of CertainTeed B glass fiber), and unspecified glass wool fibers. Inhalation exposure of F344 rats to Owens-Corning FG insulation fiberglass with binder (4 to 6 μm in diameter and > 20 μm long) significantly increased the incidence of mononuclear-cell leukemia in rats (males and females combined). Glass-fiber-related pulmonary and tracheal-bronchial lymph-node lesions were observed but were less severe than for exposure to special purpose fibers.

OK, the effects are less severe, but still something that would be an issue. But then almost every house in America is insulated with fiberglass, and I suspect the industry had a lot to say about this one. The NTP's recommendations for dealing with it:

Follow safe work practices and wear appropriate protective equipment, such as long-sleeved work clothing or disposable coveralls, a respirator, safety glasses, and gloves.

Once the stuff is in the wall and covered with drywall, there isn't going to be a lot of risk from glass fibers getting into the air. But anyone working with the stuff should be going beyond just regular work clothing that goes home in the car with you, and should start thinking about tyvek suits and high quality respirators, forget the cheap paper things. Calling fiberglass the asbestos of the 21st century is an overstatement, but it is clear that the stuff should be handled properly and carefully.

Download the NTP fact sheet here and see also: Fiberglass: Is Pink Really Green?

It is getting harder and harder to figure out what one can safely use as an insulation in green, healthy design. Expanded polystyrene has, yes, styrene, and fire retardants; sprayed polyurethane has issues; we are running out of options.

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Tags: Green Building

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