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Cigarette Smoking & Lead
Toxicity
By Robert Taylor of The LEAD
Group Inc.
This is a summary of a longer and fully
referenced article that can be found at Taylor
Tobacco & Lead Toxicity 20101005 PDF
What has tobacco got to do with lead?
Tobacco leaves trap both radioactive (Pb-210) and
non-radioactive (Pb-206) lead from the atmosphere on their surface, due to the
presence of trichomes (sticky hairs that trap particles and retain them after
washing with water). This is believed to be the main source of lead in tobacco.
Pb-210 represents a fraction of the lead trapped, being measured in nanograms
while Pb-206 is measured in micrograms.
Around 11% of lead from cigarettes enters the
smoke, and roughly half of that is believed to enter the lungs of smokers. The
bulk of the remainder is found in the ash, though some contaminates the
environment, increasing the lead levels of dust in the households of smokers.
Illegal tobacco tends to have higher levels of
heavy metals including lead, while lead has sometimes been added to tobacco or
marijuana to increase their weight.
Being insoluble, small quantities of Pb-210 are
retained in lungs, releasing radiation as it decays to Polonium-210. The average
1 pack a day smoker is exposed to the equivalent of over ten times the average
US background radiation exposure, roughly one third of this from Pb-210. It is
unlikely to be predominantly responsible for the increased risk of lung cancer
by itself.
Cigarettes contain over 4000 chemicals; over 20
are probably carcinogenic and over 60 mutagenic (affecting genes and their
impacts). Cigarette smoke increases the vulnerability of lung tissue to
radiation and other carcinogens. There is weak and dated evidence that Pb-210
could play a role in lung cancer.
Lung Cancer Mortality: active and passive smoking
Smokers of European descent have a 22.1% risk of
dying of lung cancer before the age of 85 if male, and 11.9% if female, with the
comparable rates for non smokers being 1.1% and 0.8%.
Significant exposure to environmental tobacco
smoke (ETS or passive smoking) increases the risk of dying of lung cancer by
15-31% (RR 1.15-1.31) for people living with a smoker [RR (Relative risk or Risk
Ratio): added risk to exposed individuals frequently translated into a
percentage http://en.wikipedia.org/wiki/Relative_risk]
or around 24% (RR 1.24) if exposed to ETS through work. However, according to
one study, this includes more than doubling the risk for former smokers, while
increasing the risk for most non-smokers by very little (OR 1.05, similar to
taking over 50 mg a day of vitamin E supplements OR 1.03-1.1). [OR (odds ratio):
the probability of the event divided by the probability of an event not
occurring – not the same as RR and the translation of this figure into
percentage increase can be very misleading see http://stats.org/stories/2008/odds_ratios_april4_2008.html]
Individuals exposed to large amounts of ETS as children could have their risk
doubled (HR 2.00-3.63) [HR (Hazard Ratio) – similar to RR see http://en.wikipedia.org/wiki/Hazard_ratio]
Other Risk Factors and variations
The risk of contracting cancer from ETS (with the
above figures adjusted for 84% mortality – roughly 18-38% and 28%
respectively) is slightly less than the risk of living beside a major road (OR
1.47) [OR (odds ratio): the probability of the event divided by the probability
of an event not occurring – not the same as RR and the translation of this
figure into percentage increase can be very misleading see http://stats.org/stories/2008/odds_ratios_april4_2008.html],
less than the risk of large scale wood dust exposure (OR 1.8), much less than
the risk of long term solvent exposure (OR 2.8) and a fraction of the risk of
intensive (4 dishes a day for 25 years) fried food preparation for Chinese women
which increases risks by over 300% (OR 1.92-6.15). It is only slightly higher
than exposure to wood and coal smoke from cooking and heating in Europe (OR
1.24). The lung cancer risk of ETS is not unique and cannot be considered
separately from that of other air toxics.
Japanese male smokers are 66% (RR 0.34) less
likely to die of lung cancer as comparable smokers in the USA, but among
non-smokers Japanese have 2-3 times the lung cancer mortality of US individuals.
This variation is not unique: lung cancer should not be attributed to a single
factor and may be influenced by environmental, genetic and nutritional factors.
Cardiovascular impacts
Being a male cigarette smoker more than doubles
your risk of cardiovascular mortality, while ETS exposure increases your risk of
cardiovascular problems by up to 30%. Lead probably plays a significant role in
this, with relatively modest increases in blood lead greatly elevating
cardiovascular risk.
What smoking and ETS does to the developing
foetus: Why pregnant women shouldn’t smoke
Both ETS and lead, whether from ETS or elsewhere,
have strong impact on intellectual and behavioural development. Both increase
the risk of premature birth, lower IQ, ADD/ADHD and behavioural problems. ETS
and lead have synergistic properties, best demonstrated by the fact that the
mother being in the top third for US prenatal exposure to tobacco smoke (smoking
or ETS) and the child having the a blood lead ≥ 1.3 µg/dL (one third of
the American teenage population) increases the risk of the child having ADHD by
eight times, while either factor in isolation only doubles the risk.
Smoking during pregnancy may have more of an
impact on children’s blood lead levels than ETS after birth, with every 10
cigarettes per day smoked in 1990 increasing umbilical cord lead by 15%.
Smoking, ETS & blood lead levels
Being a cigarette smoker in the USA in 1998-2002
more than tripled the risk of having a blood lead above 5 µg/dL.
In 1988-1994, US children with high exposure to
ETS were four times more likely to have blood levels above 10 µg/dL and had 38%
higher blood lead than children with little ETS exposure. In the 1990s, as
leaded petrol was phased out, the lead content of cigarettes sold in western
countries roughly halved and the ETS exposure of American children of
non-smokers declined by two thirds. However, the decline has been much lower for
all children 4-11 (37.7%), and does not account for contamination of household
dust by cigarette lead. The children of smokers are still at significant risk of
increased lead levels, and these risks are likely to be greater for infants who
have higher rates of lead absorption and greater home exposure.
The impact of ETS on adults in 1998-1994 was to
increase blood lead by around 30%, with much higher impacts among whites and
much lower impacts among blacks and Hispanics. Since then the lead content of
cigarettes has roughly halved and ETS exposure for non-smokers has fallen by
around 75%. The most recent large scale study of American data from urine
(1998-2002) found no increased risk for lead levels from high ETS for Mexican
Americans, no risk at lower exposure for women or people below the poverty line
and higher ETS exposure have no greater risk than lower level exposure for
whites.
Limiting smoking in public places: A success
story
It is unlikely that ETS is now a major source of
lead for non-smoking adults in countries that have limited areas where smoking
can occur in public places.
Smoking accelerates the release of lead from bone
storage
80-95% of lead is stored in the bones. Smoking
increases the rate of resorption (release of minerals, including lead, from the
bone), particularly affecting the type of bone that provides the largest long
term store of lead, cortical bone. It also reduces oestrogen [US spelling
estrogen] levels, increasing the impact of menopause. The impact of smoking on
bone is still poorly understood.
Smoking depletes vitamins
Vitamin D, which reduces deposition of lead in
the bone, and vitamin C & E, which reduce the damage lead does to body
organs, are depleted by cigarette smoking. Smokers are advised to increase their
C intake and, more cautiously, their vitamin D but Vitamin E supplementation
carries significant risks, including lung cancer.
Recommended Reading
ACS [American Cancer Society] Cancer Facts and
Figures 2010. www.cancer.org/acs/groups/content/@epidemiologysurveilance/documents/document/acspc-026238.pdf
[basic outline of cancer statistics also see Woloshin reference ]
Darren R Brenner, Rayjean J Hung, Ming-Sound Tsao
, Frances A Shepherd , Michael R Johnston, Steven Narod, Warren Rubenstein and
John R McLaughlin Lung cancer risk in never-smokers: a population-based
case-control study of epidemiologic risk factors BMC Cancer 2010, 10:285
doi:10.1186/1471-2407-10-285 www.biomedcentral.com/1471-2407/10/285
[A recent Canadian study that found a wide range of lung cancer risks
from occupational exposure to substance such as wood dust, solvents and smoke.]
Bruno RS, Leonard SW, Atkinson J, Montine TJ,
Ramakrishnan R, Bray TM, Traber MG. Faster plasma vitamin E disappearance in
smokers is normalized by vitamin C supplementation Free Radical Biology and
Medicine Vol. 40, Iss. 4, 15 February 2006, Pages 689-697 http://www.sciencedirect.com/science/article/pii/S0891584905006611
[Given that levels of both Vitamin C & E are reduced in smokers,
taking 1000 mg a day of vitamin C reduced
the usage of Vitamin E by 25%]
Tim Byers Nutrirition and Lung Cancer Am. J. of
Respiratory and Critical Care Medicine Vol 177. pp. 470-471, (2008) http://www.atsjournals.org/doi/pdf/10.1164/rccm.200711-1681ED
[Ruminates on the fact that while
increased fruit and vegetable intake reduces lung cancer risks, taking
equivalent quantities of vitamin E or beta-carotene supplements increases lung
cancer risks]
Committee on Secondhand Smoke Exposure and Acute
Coronary Events; Institute of Medicine (IOM) Secondhand Smoke Exposure and
Cardiovascular Effects: Making Sense of the Evidence National Academies Press
2010 [A significant overview of the role of ETS in cardiovascular problems]
Tanya E. Froehlich, Bruce P. Lanphear, Peggy
Auinger, Richard Hornung, Jeffery N. Epstein, Joe Braun, Robert S. Kahn
Association of Tobacco and Lead Exposures With Attention-Deficit/Hyperactivity
Disorder Pediatrics Vol. 124 No. 6 Dec. 2009, pp. e1054-e1063
(doi:10.1542/peds.2009-0738) http://pediatrics.aappublications.org/content/124/6/e1054.full.html
[Found that prenatal ETS exposure and higher blood lead levels doubled
the risk of ADHD but that both factors together increased the risk eightfold. A
previous paper from this group noted little impact from postnatal ETS exposure.]
H Hu, M.M Téllez-Rojo, D Bellinger, D Smith,, A
S. Ettinger, H L Figueroa, J Schwartz, L Schnaas, A M-García, and M H-Avila
Fetal Lead Exposure at Each Stage of Pregnancy as a Predictor of Infant Mental
Development Environ Health Perspect. 2006 November; 114(11): 1730–1735. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1665421/
[A study that clearly indicates the impact of prenatal exposure to lead.]
Masayuki Kaji , Mikio Gotoh , Yasuko Takagi
and Hiroyuki Masuda Blood lead levels in Japanese children: Effects of
passive smoking Env. Health and Prev. Medicine Vol 2 No 2 July 1997 http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2723438/pdf/12199_2008_Article_BF02931969.pdf
[Found markedly different impacts for ETS exposure for younger children
and older children.]
Jolanta Lissowska, Alicja Bardin-Mikolajczak, T
Fletcher, D Zaridze, N Szeszenia-Dabrowska, P Rudnai, E Fabianova, A Cassidy, D
Mate Lung Cancer and Indoor Pollution from Heating and Cooking with Solid Fuels:
The IARC International Multicentre Case-Control Study in Eastern/Central Europe
and the United Kingdom Am. J. Epidemiol. (15 August 2005) 162 (4): 326-333. doi:
10.1093/aje/kwi204 http://aje.oxfordjournals.org/content/162/4/326.full
[Finds that using wood and coal for both cooking and heating increases
lung cancer risks by 24%]
David M. Mannino, Rachel Albalak, Scott Grosse
& James Repace Second-hand Smoke
Exposure and Blood Lead Levels in U.S. Children Epidemiology, Vol. 14, No. 6,
November 2003 http://journals.lww.com/epidem/Abstract/2003/11000/Second_hand_Smoke_Exposure_and_Blood_Lead_Levels.15.aspx
[Found that individuals with high levels of ETS exposure had 38% higher
blood lead levels than those with minimal ETS exposure]
David M. Mannino, David M. Homa, Thomas Matte and
Mauricio Hernandez-Avila Active and Passive Smoking and Blood Lead Levels in
U.S. Adults: Data From the Third National Health and Nutrition Examination
Survey Nicotine & Tobacco Research 2005 7(4):557-564 http://ntr.oxfordjournals.org/content/7/4/557.abstract
[Found that adults with high levels of ETS exposure had 30% higher blood
lead levels than those with minimal ETS exposure. But also found wide ethnic
disparities and noted he could not explain the degree of the link as non-smokers
absorb a fraction of elements in ETS.]
Tomomi Marugame, Tomotaka Sobue, Hiroshi Satoh,
Shoko Komatsu, Yoshikazu Nishino, Haruo Nakatsuka, Tomio Nakayama, Takaichiro
Suzuki, Toshiro Takezaki, Kazuo Tajima, Suketami Tominaga Lung cancer death
rates by smoking status: Comparison of the Three-Prefecture Cohort study in
Japan to the Cancer Prevention Study II in the USA Cancer Science Vol. 96, Is.
2, pages 120-126, February 2005 http://onlinelibrary.wiley.com/doi/10.1111/j.1349-7006.2005.00013.x/full
[A major study that found that Japanese smokers were around one third as
likely as American smokers to die of lung cancer while for non smokers the
figures were almost reversed.]
Nawrot, Tim; Staessen, Jan A Low-Level
Environmental Exposure to Lead Unmasked as Silent Killer Circulation
2006;114:1347-1349 http://circ.ahajournals.org/content/114/13/1347.full
[Provides an outline and commentary on an article on the impact of lead
on mortality of even low lead
levels.] Brianna Rego The Polonium Brief - A Hidden History of Cancer,
Radiation, and the Tobacco Industry. Isis, 2009,
100:453-84 www.briannarego.com/RegoIsis2009.pdf
[A long article on the tobacco industry’s reaction to findings of a
link between polonium-210, lead-210 and lung cancer. P458-468 summarizes early
research into the subject]
Marc Rhainds and Patrick Levallois Effects Of
Maternal Cigarette Smoking And Alcohol Consumption On Blood Lead Levels Of
Newborns Am J Epidemiol Vol 145, No. 3, 1997 http://aje.oxfordjournals.org/content/145/3/250.full.pdf
[Important study that found that maternal smoking habits during pregnancy
can have impacts on a child’s lead burden than post natal ETS exposure,
increasing umbilical cord lead by 15% per 10 cigarettes smoked per day]
Patricia A. Richter, Ellen E. Bishop, Jiantong
Wang, and Monica H. Swahn Tobacco Smoke Exposure and Levels of Urinary Metals in
the U.S. Youth and Adult Population: The National Health and Nutrition
Examination Survey (NHANES) 1999-2004 Int J Environ Res Public Health. 2009
July; 6(7): 1930-1946. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2738890/
[A major study with a questionable method. Measuring lead in urine
measures how much lead is being excreted and significant lead is stored in bone
rather than excreted. Smoking also increases lead release from the bone. The
summary chose to highlight the similar increases in lead from smoking and ETS,
downplaying the fact that for many groups in the study increasing levels of ETS
had little or no impact on lead excretion. A vital but flawed study]
SE Schober, C Zhang,
DJ Brody Disparities in Secondhand Smoke Exposure - United States,
1988-1994 and 1999-2004 JAMA Vol 300 No9 September 3 2008 p1019-1020 http://jama.jamanetwork.com/article.aspx?articleid=182509
[An examination of data on ETS from NHANES studies highlighting ethnic,
racial, age and sex based variations.]
Kees van der Griendt Smokers Prevalence vs. Lung
Cancer Rates Flags and Icons www.kidon.com/smoke/percentages3.htm#note
[Compares national rates of cigarette smoking to deaths from lung cancer. Finds
much variability but an obvious limitation is that it only uses current smoking
rates rather than including previous smoking rates.]
Mohsen Vigeh, Kazuhito Yokoyama, Zahrabigom
Seyedaghamiri, Atsuko Shinohara, Takehisa Matsukawa, Momoko Chiba, Masoud
Yunesian Blood lead at currently acceptable levels may cause preterm labour
Occup Environ Med doi:10.1136/oem.2009.050419 http://oem.bmj.com/content/early/2010/08/26/oem.2009.050419.abstract
[The findings of this paper are important since smoking is associated with
preterm labour, and therefore lead may well play a significant role]
P Vineis, L Airoldi, F Veglia, L Olgiati, R
Pastorelli, H Autrup, A Dunning, S Garte, E Gormally, P Hainaut, C Malaveille, G
Matullo, M Peluso, K Overvad, A Tjonneland, F Clavel-Chapelon, H Boeing, V Krogh,
D Palli, S Panico, A Agudo, C Martinez , M Dorronsoro, A Barricarte, L Cirera, J
Quiros, G B J Manjer, B Forsberg, N E Day, T J Key, R Kaaks, R Saracci and E
Riboli. Environmental tobacco smoke and risk of respiratory cancer and chronic
obstructive pulmonary disease in former smokers and never smokers in the EPIC
prospective study BMJ, doi:10.1136/bmj.38327.648472.82 http://www.bmj.com/content/330/7486/277
[Discovered that ETS greatly increased lung cancer risks for former
smokers but very little for adult non-smokers. A latter paper by this group
found that the cancer risk for adults who were exposed to large amounts of ETS
as children was doubled]
Marc G. Weisskopf,
Nitin Jain, Huiling Nie, David
Sparrow, Pantel Vokonas, Joel
Schwartz, Howard Hu A Prospective Study of Bone Lead Concentration and Death
From All Causes, Cardiovascular Diseases, and Cancer in the Department of
Veterans Affairs Normative Aging Study Circulation. 2009;120:1056-1064. http://circ.ahajournals.org/content/120/12/1056.full.pdf+html
[Finds that males in the top third of bone lead levels, a better measure of long
term lead exposure than blood lead, were more than twice as likely to die and
five times more likely to die of cardiovascular problems.]
Steven Woloshin , Lisa M. Schwartz , H . Gilbert
Welch The Risk of Death by Age, Sex, and Smoking Status in the United States:
Putting Health Risks in Context J Natl Cancer Inst 2008;100: 845 – 853 http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3298961/pdf/djn124.pdf
[A much needed reference that accounts for death from cardiovascular and cancer
by decade among smokers, former smokers and non-smokers.]
*
DISCLAIMER:
The
views expressed herein are not necessarily the views of the Australian
Government, and the Australian Government does not accept responsibility
for any information or advice contained herein.
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