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Environmental tobacco smoke and tobacco related mortality in a prospective study of Californians, 1960-98

BMJ 2003; 326 doi: (Published 15 May 2003) Cite this as: BMJ 2003;326:1057

Rapid Response:

Re: An interesting debate

With the demise of the Tobacco Institute, the internet has become
infested with so-called Smokers' Rights groups. They quote pseudo-scientific arguments advanced by tobacco industry consultants to
convince the gullible that it is OK for smokers to liberate poisonous air
pollution inside buildings.

One of the most common specious arguments is the use of occupational
chemical Threshold Limit Values (TLVs) on carefully selected individual
components of secondhand smoke (SHS) to make the claim, as Mr. Atherton
does, "Not one comes close to any physically attainable danger level."

In the Gori-Mantel 100 cubic meter (m3) room hypothetical example Mr.
Atherton cites, 14,000 micrograms (ug) of SHS fine particles (PM2.5) would
be liberated per cigarette smoked. The WHO standard for PM2.5 is 25 ug/m3
and is the appropriate standard to use. This standard would be violated
by smoking less than 0.002 of a cigarette. Smoking a bit more than 3-1/2
packs of cigarettes would pollute the room to more than 10,000 ug/m3,
which would exceed the TLV for respirable dust. Thus, the example
Atherton cites actually refutes his argument.

More to the point, TLVs are limits intended for use in industrial
hygiene as guidelines, not as indoor air quality standards. Many TLVs
were set primarily for acute, not chronic, toxicity. TLVs do not take into
account synergistic effects with other chemicals in a mixture such as SHS,
and thus are even less valuable when considering complex mixtures in non-
industrial environments.

In fact the ACGIH committee that sets TLVs concedes that they do not
reflect long-term health effects such as cancer or reproductive damage or
illnesses such as fatigue, headaches, or decreased nerve conduction
response. TLVs exclude the sick, the elderly, asthmatics, and other
hypersensitive persons (Lippy and Turner, 1991). Finally, two potent
bladder carcinogens in SHS, 4-aminodiphenyl and 2-naphylamine, have no
permissible level of exposure (NIOSH, 1996).

Moreover, Castleman and Ziem (1988) found serious conflicts of
interest in the setting of Threshold Limit Values (TLVs). Corporate
representatives listed officially as “consultants” were given primary
responsibility for developing TLVs on proprietary chemicals of the
companies that employed them.

Finally, the cigarette-equivalent arguments quoted uncritically by
Atherton and attributed to Gori and Mantel make an unstated and
unjustifiable assumption of a linear dose-response relationship. There is
demonstrable evidence that the dose-response relationship between tobacco
smoke exposure and cardiovascular or lung cancer mortality is highly non-
linear, rising steeply at small doses and saturating at the doses inhaled
by smokers (Repace, 1992; Pope et al., 2009).

The National Academy of Sciences (2009) report - the latest
scientific report on SHS in a long line dating back to 1986 - concluded:
"there is a causal association between smoking bans and decreases in heart
attacks." The time for debate is long gone. Governments contemplating
smoking bans are taking heed.

Castleman BI, and Ziem GE (1988) Corporate Influence on Threshold
Limit ValuesAmerican Journal of Industrial Medicine 13531-559.

Lippy BE, Turner RW (1991). Complex Mixtures in Industrial
Workspaces: Lessons for Indoor Air Quality Evaluations. Environmental
Health Perspectives 95: 81-83.

NIOSH (1996). NIOSH Pocket Guide to Chemical Hazards. U.S. Centers
for Disease Control and Prevention, DHHS Publication No. 94-116.

Pope CA 3rd, Burnett RT, Krewski D, Jerrett M, Shi Y, Calle EE, Thun
MJ (2009). Cardiovascular mortality and exposure to airborne fine
particulate matter and cigarette smoke: shape of the exposure-response
relationship. Circulation 120:924-927.

Repace JL. Is the dose -response curve between tobacco smoke
exposure and lung cancer really linear from active smoking to passive
smoking?" ENVIRONMENT INTERNATIONAL 18: 427-429 (1992).

Competing interests:
The author is a secondhand smoke consultant.

Competing interests: No competing interests

26 December 2009
James L. Repace
Visiting Asst. Clinical Prof., Tufts Univ. School of Medicine, and President, Repace Associates, Inc
101 Felicia Lane, Bowie, MD 20720