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Health
effects of smoking tobacco, smokeless tobacco and nicotine:
Female infertility1
Summary:
·
Cigarette
smoking. There is strong epidemiological
and biochemical evidence that cigarette smoking damages female fertility.
·
Smokeless
tobacco: The evidence for
smokeless tobacco affecting female fertility is virtually lacking.
Smokeless tobacco and NRT contain nicotine, which make constrict the
blood supply to the oviduct, but no epidemiological studies have been
carried out.
Anatomy of the oviduct (Fallopian tube) The oviduct
(consisting of infundibulum which wraps around
ovary, the ampulla where the tube opens close
to the ovary, and the isthmus the narrow tube leading to the uterus),
Pathology. The oviduct, if malfunctioning, is likely to be
associated with increased infertility and ectopic
pregnancy.
Epidemiological evidence. Women of child bearing age who
actively inhale mainstream smoke have higher rates of infertility,
spontaneous abortion, ectopic pregnancy, tubal infertility, increased time to conception, and
intrauterine growth retardation, than nonsmokers.
Physiological evidence. The oviduct’s infundibulum picks up the oocyte
complex and moves it to the ampulla where
fertilization occurs. Simultaneously the oviduct moves sperm from uterus
to ampulla, later moves the fertilized embryo
back along the oviduct to the uterus, timing this move in response to
hormonal or chemical signals from the woman and the embryo, to provide
the best receptivity for implantation.
Most current evidence links smoke to effects on:
- The
oocyte pickup process. This process has
been observed during laparoscopic surgery. It depends on (i) ciliary beating of
cells and (ii) their stickiness on the surface epithelium of both oocyte and oviduct infundibular
fimbria.
- Embryo
transport. This depends on (i) Ciliary beating. The ampulla and isthmus sections of the oviduct are
lined by ciliary cells which beat towards
the uterus. (ii) Smooth muscle contraction.
Effect of
smoking tobacco, smokeless tobacco, and nicotine
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Cigarette smoke
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Smokeless tobacco
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Nicotine products
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Ciliary beat frequency
Mainstream
smoke solutions of cigarette brands, filtered or unfiltered, inhibit
the frequency of the beat of cilia in the oviduct in a dose dependent
manner.
Cyanide
(as HCN) is present in cigarette smoke (typically 300 micrograms per Holiday cigarette, 480 micrograms
per Marlboro cigarette) and in cigarette smoke solutions as KCN, in
sufficient quantity to inhibit the oocyte
pickup rate and
in-vitro infundibular bio-assay.
The effect is dose-dependent.
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Contains
nicotine.
Does
not contain hydrogen cyanide (HCN) or potassium cyanide (KCN).
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No
inhibitory effect from nicotine.
Does
not contain HCN or KCN.
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Oocyte pick-up rate
Cigarette
smoke Cigarette smoke solutions of almost all brands, whether filtered
or unfiltered, commercial, “harm reduction” or research
cigarettes, reduced this rate by over 60%. The pick-up rate is
inhibited by KCN in the levels found in cigarette smoke solutions.1
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Contains
nicotine.
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No
inhibitory effect from nicotine
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Smooth muscle contraction
Smoke
solutions from almost all traditional brands reduced muscle contraction
by over 80%. Contraction of the ampulla
inhibited during smoking, and not completely normalised after smoking.
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Contains
nicotine.
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Nicotine
decreases blood supply to the oviduct in rats, and in the Rhesus
monkey, slowed oviductal contraction. This
would be expected to interfere with transport of the fertilised embryo
and fertility.
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Cadmium. Present in tobacco of
manufactured cigarettes tobacco (0.8 ppm dry
weight, and in cigarette smoke: (56 ng per
cigarette in NZ Holiday Extra mild,2 191ng per cigarette
mean in 16 Canadian regular brands)3. Found to be higher in
ovary of smokers (150ng/g) versus nonsmokers (115 ng/g).
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Cadmium
is present in trace amounts in oral tobacco (0.4 micrograms per gram
(parts per million) dry weight).4 WHO sets a maximum of 52
micrograms per day in food.5
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Cadmium
not present in nicotine replacement products.
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1 Talbot P. Riveles K. Smoking and reproduction: the oviduct as a
target of cigarette smoke. Reproductive Biology and Endocrinology 2005; 3: 52 doi:10.1186/1477-7827-3-52.
http://www.rbei.com/content/3/1/52
2
Fowles J. Chemical composition of tobacco and cigarette
smoke in two brands of NZ cigarettes. ESR 2003. www.ndp.govt.nz
3.
Ministry
of Health Planning. Government of British Columbia. What’s in cigarettes. Ingredients of mainstream smoke of
cigarettes. http://www.healthservices.gov.bc.ca/cgi-bin/ttdr_ingredients_search.cgi?constituent=all Accessed 25
October 2005. Health Canada intensive test mode.
4.
Wahlberg I. TSNAs and metals in Swedish snus and
in NZ cigarettes. Report to Health New Zealand Ltd 2003. http://www.endsmoking.org.nz/oralsnuff.htm
5.
Rodu B, Jansson C. Smokeless tobacco and oral cancer: a review of the risks and determinants.
Crit Rev Oral Biol
Med 2004; 15: 252-263.
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