Friday, August 19, 2005

Information Quality Act Appeal Tries to Put Naphthalene in Moth Balls

BrooklynDodger was wandering the NIEHS website and encountered yet a new front in public health policy. People - industry - can appeal virtually any publication on health hazards. This post has to do with listing of naphthalene as "reasonably anticipated to be a human carcinogen" in the NTP Report on Carcinogens.

Naphthalene -- Information Quality Act Request for Reconsideration

IARC monographs and Report on Carcinogens listings serve two functions. The public health function is warning the public of chemicals which pose a carcinogenic hazard.

Another function is determining whether data on a chemical meet the criteria for declaring a chemical as known to be carcinogenic in humans, or reasonably anticipated [NTP] or probably or possibly [IARC] carcinogenic. An ongoing scientific project compares the laboratory evidence for known human carcinogens to the human evidence. Agents which behave in the laboratory similarly to those agents known to be carcinogenic in humans ought to be assumed to pose the same risk in humans, with or without a body count. Scientific evaluation of data against the criteria for assessment serves this purpose.

Attacks on the public health front, fomented by economic interests, threaten to undermine the scientific project as well.

So here comes naphthalene. Since BrooklynDodger was a pup, multi-ringed (5 ringed) polynuclear aromatic compounds were considered the bad boys; lower ringed compounds, presumably more plentiful in smoke and soot, were discounted.

The single ring, benzene, sat in the corner as the bad boy of the aromatic sequence. Naphthalene, anthracene, pyrene [not sure if the Dodger has this progression right] were neutral, and then benzopyrene was the biggest bad boy.

Now, there is some evidence that naphthalene vapor causes lung tumors in female but not male mice, and clear evidence that napthalene causes nasal tumors in rats of both genders. The mouse tumors face the "not relevant to humans" eraser by the mouse clara cell hypothesis, this years HRA [Houdini Risk Assessment] model. By NTP criteria, two species are needed for reasonably, so if the mice are erased, so is "reasonably." By IARC criteria, two studies are needed for possibly, the male and female rats are considered one study, so if the mice go, so does "possibly."

Prior to MEGO [my eyes glazed over], it appeared the industry appeal, and appeal of denial, are entirely based on procedure and not substance.

Toxicology and Carcinogenesis Studies of Naphthalene (CAS No. 91-20-3) in B6C3F1 Mice (Inhalation Studies)

Under the conditions of these 2-year inhalation studies, there was no evidence of carcinogenic activity of naphthalene in male B6C3F1 mice exposed to 10 or 30 ppm. There was some evidence of carcinogenic activity of naphthalene in female B6C3F1 mice, based on increased incidences of pulmonary alveolar/ bronchiolar adenomas.
In both male and female mice, naphthalene caused increased incidences and severity of chronic inflammation, metaplasia of the olfactory epithelium, and hyperplasia of the respiratory epithelium in the nose and chronic inflammation in the lungs.

(CAS NO. 91-20-3)
NTP TR 500

Under the conditions of this 2-year inhalation study,
there was clear evidence of carcinogenic activity* of
naphthalene in male and female F344/N rats based on
increased incidences of respiratory epithelial adenoma
and olfactory epithelial neuroblastoma of the nose.
In male and female rats, exposure to naphthalene
caused significant increases in the incidences of nonneoplastic
lesions of the nose.

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