New Evidence of Effects of Environmental Factors on Male Fertility

French and Argentinean researchers have found new evidence that environmental factors are contributing to male infertility and that they may worsen pre-existing genetic or medical risks.

The scientists, from INSERM in Rennes and Kremlin Bictre and the Hospital Italiano Garibaldi in Rosario, studied 225 men from the Litoral Sur region of Argentina - one of the world's most productive farming regions - who attended a first infertility consultation between 1995 and 1998.

The objective was to investigate the relationship between exposure to environmental agents and the seminal characteristics and serum hormone concentrations in men seeking fertility treatment. Information about lifestyle, occupation, medical history, and the type of and extent of environmental exposure encountered by the men was collected via interviews, and a variety of physical and biological tests were carried out on 189 of the group.

The researchers report today (Friday 27 July) in Human Reproduction* that they found that exposure to pesticides and solvents in particular was significantly associated with sperm threshold values well below the limit for male fertility. They also found that men exposed to pesticides had higher concentrations of serum oestradiol than unexposed men and that men exposed to solvents had lower concentrations of luteinizing hormone. All the effects were greater in men with primary infertility (never had a child) than those with secondary infertility (infertile after having had a child).

Dr Luc Multigner from INSERM, said that the findings must be treated with caution because they involved a selected population and there were potential sources of bias within the study. Nevertheless, it had clearly demonstrated that in a population of men attending for infertility consultation, environmental exposure, particularly to pesticides and solvents, was associated with dramatic changes in seminal characteristics.

"Our results suggest that toxicants act on the testes and post-testicular sites, including the accessory sex glands," he said. "The testicles are one of the most vulnerable organs to environmental, physical and chemical agents. Exposure to pesticides and solvents is significantly associated with threshold sperm values much lower than the considered limits for male fertility."

Dr Alejandro Oliva from the Hospital Italiano Garibaldi, said that Argentina had become a major user of pesticides with turnover of import and export increasing by 270% between 1990 and 1998 compared with an increase of 49% for France and 62% for the USA.

"There has been rising concern in many Western countries about the deleterious effects of environmental chemicals on male reproduction. Attention to this issue should now be given to developing countries," he said.

References:

*Contribution of environmental factors to the risk of male infertility. Human Reproduction. Vol 16. No 8. pp 1768-1776.

Notes:
1 PDF version of this press release and full embargoed text of the paper with complete results and participating research teams, can be found from 09.00hrs BST Wednesday 25 July on website: http://www3.oup.co.uk/eshre/press-release/aug301.pdf
2 Human Reproduction is a monthly journal of the European Society of Human Reproduction and Embryology (ESHRE). Please acknowledge Human Reproduction as a source. ESHRE's website is: http://www.eshre.com
3 Printed texts available on request from Dr Helen Beard, Managing Editor. Tel: +44 (0) 1954 212404 or email: beardh@humanreproduction.co.uk