Men being exposed to phthalates — chemicals found in certain everyday things like wallpaper, nail polish, perfume, and floors — should be worried about their sperm, according to a new study. The research showed an association between phthalate exposure and low levels of sperm motility.

Phthalate molecules, also known as DEHP molecules, leak out of soft plastics, which means we are exposed to them daily. The chemicals can be absorbed through food and drink, skin contact, and inhalation. And their levels in a person's system can be measured by a simple urine test.

Researchers tested 300 men between the ages of 18 and 20 for both phthalate levels and sperm maturity and motility, which refers to the sperm's ability to move actively and spontaneously. For the first quarter of men with the lowest level of exposure to phthalates, 57 percent of their sperm cells were able to move forward. This was compared to the quarter of participants with the highest levels of exposure, who had only 46 percent of their sperm moving forward.

The study is the first of its kind in that it analyzed the same metabolites in men from the general population, and adjusted for the concentration of urine and time since the last ejaculation. Men from the general population were deemed most relevant to the study because men with fertility problems, who are often used for this type of study, usually have reduced semen quality to begin with. Previous studies on animals, though, have shown that phthalates negatively affect the male reproductive system.

“There are other studies that support our findings with regard to the link between DEHP metabolites and sperm motility, but also studies that have not found any connection,” said Jonatan Axelsson, researcher at the Department of Laboratory Medicine, Lund University, in a press release. “However, we should be aware that there may be a problem and that it can be an important issue for future research.

Previous research has also pointed out a link between high sperm motility and fertility, meaning these findings could indicate that the more a man is exposed to DEHP, the smaller his chances of having children. DEHP is already on the European Union’s list of substances with hazardous properties.

Source: Axelsson J, Rylander L, Rignell-Hydbom A, Jonsson B, Lindh C, Giwercman A. “Phthalate Exposure And Reproductive Parameters In Young Men From The General Swedish Population.” Environmental International. 2015.