Transcript Environmental & Occupational Factors affecting Human Fertility

Effect of Environmental Factors
on
Human Fertility
By: Siamak Bashar
PhD student in Public Health ( Epidemiology)
Department of Health Sciences
Walden University
Primary and Secondary Infertility
Total Infertility Cases Despite having unprotected
intercourse for at least 12 months:
Primary infertility
70%
Secondary infertility
30%
Female: Has never conceived
Male: Has never impregnated a female
Female: Has previously conceived but is
subsequently unable to do so
Male: Has previously impregnated a female but
is subsequently unable to do so
Hatcher RA, Trussell J, Stewart F, et al. 1994
Stewart GK. 1998
Fertility Facts
Frequency: 1 out of 6 couples in the US
Responsibility: 35% female infertility
35% male
20% both
10% unknown
Maternal Age USA
20-24
4.1% 30-34
9.4%
25-29
5.5% 35-39
19.7%
Healy et al, 1994
Among couples with identifiable causes of
infertility
Female
Factors
40%
40%
Male
Factors
20%
Unknown/Both
Nelson, A.L, Marshall, J.R. 2004.
What can cause infertility?
Unexplained-18%
Female
Male
• Ovulation disorders • Sperm count and
defects
• Tube/uterus
blockage
• Erectile or
ejaculation
• Cervix
deficiency
• Endometriosis
• Other
Intrinsic vs. Extrinsic, Environmental
Decrease Human Fertility
&
Reproductive Health Level
•Increase percentage of US Women with impaired Fecundity by age
( 1982-2002)
•Declining Male Testosterone (Travison et al. J Clin Endocrinol Metab,
2006)
•Increasing Testicular Cancers in the United States ( Shah et al. Journal
of Andrology, 2007)
•Decreasing Age of Puberty ( Euling , et al. Paediatrics ,2000)
What Is Changing?
Environmental Influences
on Human Reproduction
• Environmental Chemical
•Nutrition
•Life style
•Emerging old and starting New Sexual Transmitted Diseases
• Behavioural Factors
•Interaction Among the Factors
Infertility From Public Health Point
of View
The WHO estimates that there are 60 million to 80 million infertile
couples worldwide
•Core infertility: a certain percentage of couples who would be infertile as a
result of conditions that we cannot prevent, treat, or even know
•Acquired Infertility: which generally indicates that there are causes in the community
responsible for the excess of infertile couples
FATHALLA, M,(1990). Fertility Overview
Acquired Infertility or Infertility Caused
by Environmental Factors
1.Lifestyle factors including: age, weight, smoking, diet, exercise,
psychological stress, caffeine consumption, and alcohol
consumption
2. Occupational &Environmental Factors:
• Physical: such as Light, Temperature, Altitude, and Radiation
• Chemical: Such as Natural or man-made
• Biological: Such as Viruses, Microorganisms
3. Behavioral Factors: Such as Stress and Drug addiction
Homan, et al 2007
http://humupd.oxfordjournals.org/cgi/content/abstract/13/3/209
Environmental Factors Related to
Infertility
•Toxic agents
•Tobacco use
• Alcohol Use
• Radiation
•Sexual Transmitted Diseases
Sharpe, R.M., & Franks, S., (2002). Environment, lifestyle and infertility — an inter- generational issue, Nature
Cell Biology & Nature Medicine8 (S1), S33- S40
http://www.nature.com/fertility/content/full/ncb-nm-fertilitys33.html
Toxic Agents & Infertility
Female
Male
•Lead poisoning
reduces conception
rates, associated
with fetal wastage
•Lead reduces sex
drive, sperm count
•Pesticides reduce
sperm count
Stewart GK. 1998.
Chemicals
&
Their Adverse Reproductive Health Effects
•DDT/DDE (a): Reduced parity, impaired lactation, decreased semen quality, impaired
fertility, and small-for-gestational-age babies
•Dibromochloropropane : Decreased sperm counts & infertility
•Pesticides in general :No apparent effects alone but decreased semen quality
and fecundity, spontaneous abortion, pre-term birth, and small for gestational age in
mixtures
•PCB(b): Impaired response to ovulation induction, reduced parity, impaired lactation,
and potential reduced fecundability
(a)=DDT/DDE = dichlorodiphenyltrichloroethane/dichlorobischlorophenylethylene
(b)=PCB = polychlorinated biphenyls
Younglai et al, 2006 & Hruska et al., 2000.
http://humupd.oxfordjournals.org/cgi/content/abstract/11/1/43
Tobacco Use & Infertility
•
•
•
•
•
Decreased rates of conception
Increased rates of miscarriage
Increased risk of ectopic pregnancy
Increased risk of placenta previa
Negative effects on fetus
Stewart GK. 1998.
Bouyer J, et al. Am J Epidemiology. 2003.
•
•
•
•
Sperm production
Motility
Morphology
Fertilization capacity
Cigarette Smoking and Its Adverse
Effects on Infertility
Male:
• Negatively affects sperm production, motility and morphology
• Increased risk of DNA damage
Female:
• Negatively affect the follicular microenvironment and alter
hormone levels in the luteal phase
• Early Menopause
• Increased thickness of Zona Pellucida
Homan, G.F. et al, 2007
http://humupd.oxfordjournals.org/cgi/content/abstract/13/3/209
Alcohol Use & Infertility
•
•
•
•
Decreased rates of conception
Increased rates of miscarriage
Ovulatory infertility
Negative effects on fetus
Stewart GK. 1998.
• Lower testosterone
levels
• Decreased sperm
production
• Impotence
Radiation & Infertility
Female
Ovarian failure
Male
Testicular damage or
cancer
Fetal wastage
Fetal damage
Stewart GK. 1998.
Chromosomal
aberrations
Physical Exertion / Heat & Infertility
Women
Men
Athletes may
experience reversible
amenorrhea without
long-term effects
Frequent heat exposure
can temporarily reduce
sperm production, such
as welders, fire fighters,
and ceramic workers.
Stewart GK. 1998.
Hruska et al., 2000
Sexually Transmitted Diseases &
Infertility
2.3 million
infertile couples
Chlamydia: Pelvic inflammatory Disease
Gonorrhea : Pelvic Inflammatory Disease
15–30%
Unable to
conceive
Donovan P. 1993.
Human papillomavirus
Prevention
Primary Prevention: A public health strategy focusing on primary
prevention ;e.g., through removal of risk factors for infertility such as
early detection and treatment of sexually transmitted infections and,
in particular, Chlamydia infection, Smoking, Overweight, Unhealthy
Life style, Occupation hazard, and Toxic chemical substances.
Center for Diseases Control and Prevention, 2009
http://www.cdc.gov/std/infertility/ReportCongressInfertility.pdf
Prevention
Secondary Prevention: Whereas primary prevention is
important, infertility diagnosis and treatment are relevant to public
health in their own merit.
•First, infertility is an area where health care costs are borne most often by the
individual, creating significant economic and racial disparities.
•Second, early diagnosis and treatment of underlying medical conditions
(secondary prevention) may lead to effective restoration of fertility.
•Third, infertility treatment, although generally safe, is associated with adverse health
outcomes for the mother and the child; epidemiologic surveillance efforts are increasingly
necessary to design and implement tertiary prevention programs (i.e., the prevention of adverse
outcomes of infertility treatment)
Center for Diseases Control and Prevention, 2009
http://www.cdc.gov/std/infertility/ReportCongressInfertility.pdf
Prevention
•Tertiary Prevention; the treatment of infertility,
as well as some of its outcomes, contributes to
increasing the cost of health care for all.
Public Health Policy Implications:
Research:
•In the area of primary prevention, research into modifiable causes of infertility
should be given high priority. Research is needed to elucidate the mechanisms
through which specific medical conditions lead to infertility
•In the area of secondary prevention, research is needed to evaluate the potential
benefit of early detection and treatment of conditions leading to infertility, both
among couples who are actively seeking a pregnancy and among individuals who
may want a child in the future
• In the area of clinical outcomes research and tertiary prevention, there are few and
limited economic studies assessing the cost-effectiveness of infertility treatment, the
financial impact of treatment options, and the effect of insurance coverage on access
to treatment
Public Health Policy Implications
•Community Action: Learning about potentially hazardous chemicals in
everyday products and in the workplace and their effects on babies in utero are
powerful personal motivators toward further education and activism.
Safe Work: for increasing worker safety in work place ,
1. Reduce permissible exposure levels to chemicals that harm reproduction and
development so that they are more in line with environmental exposure limits
2. Exposure assessment and monitoring in occupational settings should be expanded
3. Expand occupational health researchers’ access to workers so that health consequences
can be identified and corrected
4. Develop alliances that can improve health across different sectors. For example,
making the connection between worker safety and hospital patient safety (concerning
phthalates) and fostering alliances between environmental health groups and labour and
worker groups
Sharpe & Franks, 2002 & Woodruff et al (2008)
Thank You
References:
•Bouyer, J., et al. (2003). Risk factors for ectopic pregnancy: A comprehensive analysis based
on a large case-control, population-based study in France. Am J Epidemiology [serial on the
Internet]; 157(3): 185-194.
•Donovan ,P. (1993).Testing Positive: Sexually Transmitted Disease and the Public Health
Response. New York, NY: The Alan Guttmacher Institute.
•Euling, S. Y., et al. (2008). Role of environmental factors in the timing of puberty. Paediatrics;
121 Suppi 3:S167-71
•Fathalla, M.F., et al. (1991). Reproductive Health: A Global Overview. Annals of the New York
Academy of Sciences, Parthenon Publishing Group. Lancs. UK & New Jersey
•Fidler, A.T., & Bernstein, J. (1999). Infertility: from a personal to a public health
•Hatcher RA, Trussell J, Stewart F, et al. (1994). Contraceptive Technology. 16th revised ed. New
York, NY: Irvington Publishers, Inc.
•Healy, D.L., Trounson ,A.O., & Andersen A.N. (1994). Female infertility: causes and treatment.
Lancet, 343:1539–1544
•Homan, G.F., Davies, M., & Norman, R. (2007). The impact of lifestyle factors on reproductive
performance in the general population and those undergoing infertility. Human Reproduction
.13(3):209-223; doi:10.1093/humupd/dml056
•Infertility: A Public Health Focus on Infertility Prevention, Detection, and Management. Center for
Diseases Control and Prevention (CDC): Retrieved from CDC Website Jan 30, 2010:
http://www.cdc.gov/std/infertility/ReportCongressInfertility.pdf
•Nelson, A.L., & Marshall J.R. (2004). Impaired fertility. In Hatcher R, Trussell J, Stewart F, et al.
(Eds.) Contraceptive Technology. 18th Revised Ed. New York, NY: Ardent Media, Inc.
•Shah, M.N., et al. (2007). Trends in testicular germ cell tumours by ethnic groups in the United States
Int J Androl: 30:206-13; discussion 13-4.
•Sharpe, R.M., & Franks, S., (2002). Environment, lifestyle and infertility — an intergenerational issue, Nature Cell Biology & Nature Medicine8 (S1), S33S40http://www.nature.com/fertility/content/full/ncb-nm-fertilitys33.html
•Stewart, G.K. (1998). Impaired Fertility. In Hatcher R, Trussell J, Stewart F, et al., eds. Contraceptive
Technology. 17th revised ed. New York, NY: Ardent Media, Inc.
•Travison, T.G., et al. ( 2007). A population-level decline in serum testosterone levels in American men.
J Clin Endocrinol Metab; 92:196-202.
•Wookruff, T.J., et al. (2008). Proceeding of the Summit on Environmental Challenges to
Reproductive Health and Fertility: executive summary. Fertility and Sterility, Vol. 89, No. 2.
•Younglai , E.V., et al.(2006).Environmental and occupational factors affecting fertility
and IVF success, Human Reproduction Update, Vol.11, No.1 pp. 43–57.