Does Our Environment Affect Our Fertility? Some Examples to Help Reframe the Question

ABSTRACT

The burden of unwanted infertility appears to be increasing, but links to environmental causes have, until recently, been difficult to establish. A large body of data suggests that sperm counts have been declining in Europe and the United States, but interpretation of these statistical trends remains controversial, and the role of the environment uncertain. We were able to show that some currently used pesticides are significantly associated with reduced sperm concentration by linking pesticide concentration in men's urine to results of their semen analysis. In a follow-up study, we showed that prenatal phthalate exposure was linked to subtle differences in genital development of male offspring that could impact the child's future fertility. Researchers are increasingly able to measure levels of environmental chemicals in human samples, and are using these to identify agents that impair fertility. These methods, rather than trend analyses, may lead more directly-and more persuasively-to identifying the role of environment in human fertility.

Fertility environment - semen quality - pesticides - phthalates

REFERENCES

• 1 Chandra A, Stephen E H. Impaired fecundity in the United States: 1982-1995.  Fam Plann Perspect. 1998;  30 34-42
• 2 Swan S H, Hertz-Picciotto I. Reasons for infecundity.  Fam Plann Perspect. 1999;  31 156-157
• 3 Carlsen E, Giwercman A, Keiding N, Skakkebaek N E. Evidence for decreasing quality of semen during past 50 years.  BMJ. 1992;  305 609-613
• 4 Swan S H, Elkin E P, Fenster L. Have sperm densities declined? A reanalysis of global trend data.  Environ Health Perspect. 1997;  105 1228-1232
• 5 Swan S H, Elkin E P, Fenster L. The question of declining sperm density revisited: an analysis of 101 studies published 1934-1996.  Environ Health Perspect. 2000;  108 961-966
• 6 Irvine S, Cawood E, Richardson D, MacDonald E, Aitken J. Evidence of deteriorating semen quality in the United Kingdom: birth cohort study in 577 men in Scotland over 11 years.  BMJ. 1996;  312 467-471
• 7 Andersen A G, Jensen T K, Carlsen E et al.. High frequency of sub-optimal semen quality in an unselected population of young men.  Hum Reprod. 2000;  15 366-372
• 8 Auger J, Kunstmann J M, Czyglik F, Jouannet P. Decline in semen quality among fertile men in Paris during the past 20 years.  N Engl J Med. 1995;  332 281-285
• 9 Fisch H, Goluboff E T, Olson J H, Feldshuh J, Broder S J, Barad D H. Semen analyses in 1,283 men from the United States over a 25-year period: no decline in quality.  Fertil Steril. 1996;  65 1009-1014
• 10 Paulsen C A, Berman N G, Wang C. Data from men in greater Seattle area reveals no downward trend in semen quality: further evidence that deterioration of semen quality is not geographically uniform.  Fertil Steril. 1996;  65 1015-1020
• 11 Swan S H, Brazil C, Drobnis E Z et al.. Geographic differences in semen quality of fertile U.S. males.  Environ Health Perspect. 2003;  111 414-420
• 12 Jorgensen N, Andersen A G, Eustache F et al.. Regional differences in semen quality in Europe.  Hum Reprod. 2001;  16 1012-1019
• 13 Swan S H, Kruse R L, Liu F et al.. Semen quality in relation to biomarkers of pesticide exposure.  Environ Health Perspect. 2003;  111 1478-1484
• 14 Bonde J P, Ernst E, Jensen T K et al.. Relation between semen quality and fertility: a population-based study of 430 first-pregnancy planners.  Lancet. 1998;  352 1172-1177
• 15 Slama R, Eustache F, Ducot B et al.. Time to pregnancy and semen parameters: a cross-sectional study among fertile couples from four European cities.  Hum Reprod. 2002;  17 503-515
• 16 Alan Guttmacher Institute .Sharing Responsibility: Women Society and Abortion Worldwide, 1999. Available at: http://www.guttmacher.org/pub/sharing.pdf Accessed May 17, 2006
• 17 Herbst A L, Ulfelder H, Poskanzer D C. Adenocarcinoma of the vagina: association of maternal stilbestrol therapy with tumor appearance in young women.  N Engl J Med. 1971;  284 878-881
• 18 Klip H, Verloop J, van Gool J D et al.. Hypospadias in sons of women exposed to diethylstilbestrol in utero: a cohort study.  Lancet. 2002;  359 1102-1107
• 19 Swan S H. Intrauterine exposure to diethylstilbestrol: long-term effects in humans.  APMIS. 2000;  108 793-804
• 20 Baird D D, Newbold R. Prenatal diethylstilbestrol (DES) exposure is associated with uterine leiomyoma development.  Reprod Toxicol. 2005;  20 81-84
• 21 Ibaretta D, Swan S H. The DES story: long-term consequences of prenatal exposure. In: Harremoes P, Gee D, MacGarvin M, Stirling A, Keys J, Wynne B Late Lessons from Early Warnings: The Precautionary Principle 1896-2000. Copenhagen, Denmark; European Environment Agency 2001: 84-92
• 22 Salazar-Martinez E, Romano-Riquer P, Yanez-Marquez E, Longnecker M P, Hernandez-Avila M. Anogenital distance in human male and female newborns: a descriptive, cross-sectional study.  Available at: http://www.ehjournal.net/content/3/1/8 Accessed May 17, 2006; 
• 23 Swan S, Main K, Liu F et al.. Decrease in anogenital distance among male infants with prenatal phthalate exposure.  Environ Health Perspect. 2005;  113 1056-1061
• 24 Gray Jr L E, Ostby J, Furr J, Price M, Veeramachaneni D NR, Parks L. Perinatal exposure to the phthalates DEHP, BBP, and DINP, but not DEP, DMP, or DOTP, alters sexual differentiation of the male rat.  Toxicol Sci. 2000;  58 350-365
• 25 Foster P. Disruption of reproductive development in male rat offspring following in utero exposure to phthalate esters.  Int J Androl. 2006;  29 140-147
• 26 Centers for Disease Control and P .Third National Report on Human Exposure to Environmental Chemicals, 2005. Available at: http://www.cdc.gov/exposurereport/3rd/pdf/thirdreport.pdf Accessed May 17, 2006