Study finds lower sperm motility in men exposed to a common, everyday chemical.
It has long been known that there is a linear connection between sperm motility and chances of becoming pregnant. Sperm motility describes the ability of sperm to move properly through the female reproductive tract or through water to reach the egg. Sperm motility in mammals also facilitates the passage of the sperm through the extracellular matrix which surround the mammalian oocyte. Therefore, the causes of low sperm motility are greatly researched with phthalate exposure a new area of interest.
In animals, exposure to certain phthalates negatively affects the male reproductive function. However, human results are conflicting and mostly based on subfertile males, in whom the association between exposure and reproductive function may differ from the general population.
Now, a study from researchers at Lund University has shown men from the general population with higher exposure to the substance DEHP, a so-called phthalate, have lower sperm motility and may therefore experience more difficulties conceiving children.
Previous studies show that phthalates is an umbrella term for a group of substances based on phthalic acid, some of which are suspected to be endocrine disruptors. Many phthalates are found in soft plastics in daily surroundings such as wallpaper, sandals, nail polish, perfume, floors, carpets and more. Since phthalate molecules leak out of plastics, humans are exposed to it daily and absorb the chemicals through food, drink, skin contact and inhalation. Phthalate levels can be measured by a simple urine sample.
The current study measured metabolite levels of the phthalate DEHP (diethylhexyl phthalate) in urine as an indicator of exposure, as well as the semen quality of 300 men between the ages of 18 and 20. Results show that the higher metabolite levels the men had, the lower their sperm motility was. Data findings show that for the one quarter of the men with the lowest levels of exposure, 57 per cent of the sperm cells were moving forward, compared to 46 per cent for the quarter of the men with the highest levels of exposure.
The team state that to their knowledge their study is the only one of its kind that analyses the connection for the same metabolites in men from the general population, and that simultaneously makes adjustments based on the concentration of the urine and how much time had passed since the last ejaculation. The lab note that men from the general population may be the most relevant to study, because men with fertility problems often have reduced semen quality, including sperm motility, which may be caused by many different things.
The group surmise that their findings could indicate that the more exposed one is to DEHP, the smaller the chances are of having children. They stress that the substances break down in the body within a few days, so there is no cause for immediate concern. However, they go on to conclude that the global medical community should be aware that there may be a problem and that it can be an important issue for further research.
Source: Lund University