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Are pesticides to blame for men’s low sperm quality?

The methods used to assess the potential effects of pesticides on male fertility need an overhaul. Now researchers from Aarhus University will scrutinise the methods to get a more reliable assessment of the effects of pesticides.

2014.08.14 | Janne Hansen

Researchers are investigating if pesticider can have an effect on men's fertility. Photo: Colourbox

Men’s sperm quality is heading in the wrong direction – it has been going steadily downhill in recent decades. The reasons for the declining fertility are not exactly known, but there is focus on chemicals with endocrine disruption, including pesticides. Could it be that approved pesticides bear some of the blame? This is what scientists from Aarhus University will be studying in a new project supported by The Danish Council for Independent Research | Technology and Production.


The project aims to develop new methods so that pesticides and other chemicals can be tested more efficiently and the dangerous ones barred. In the longer term this may help to stop the decline in the sperm quality of men.


Methods not sensitive enough

With the current system, pesticides and other chemicals are examined for potential toxicity in a series of tests before they are approved. But this is apparently not good enough.


- Although approved pesticides have been tested and declared safe, some of them have subsequently been linked to fertility problems, says the leader of the project, senior researcher Martin Tang Sørensen from the Department of Animal Science at Aarhus University.


One of the problems is that the methods used to test the pesticides are not sensitive enough. One approach is to test pesticide effect on fertility on rats that have mated naturally. However, a rat is not the same as a human. Natural mating in rats may result in a normal litter size even if the male has a very low sperm quality. In humans, a poor sperm quality in men will affect fertility significantly more.


- It turns out, for example, that even approved residues of the plant growth regulator chlormequat in cereals result in a poorer sperm quality in mice – mind you that is when the sperm quality is assessed using alternative methods to the officially approved one. This hangs a large question mark over the official test procedures, says Martin Tang Sørensen.


Eggs and semen under the microscope

Along with research colleagues from Aarhus University, he will develop new and more sensitive techniques for assessing fertility. The techniques will include IVF, analyses of fertilised eggs and analyses of DNA and regulating proteins in the semen.


The experiments will be conducted with mice that are treated with a pesticide known to affect fertility and with one that is suspected of affecting fertility.


- The project will provide basic knowledge about natural mating and in-vitro fertilisation and about the genetic function of sperm cells. This knowledge can then be used to improve the assessment of potentially adverse effects of pesticides on fertility, says Martin Tang Sørensen.


The three-year project has a total budget of  DKK 6.0 million of which 5.4 million has been granted by The Danish Council for Independent Research | Technology and Production.


For further information please contact: Senior researcher Martin Tang Sørensen, Department of Animal Science, email: MartinT.Sorensen@agrsci.dk, telephone: +45 8715 7819