Dogs offer clue to human sperm decline

Chemicals in household carpets and flooring, clothing and upholstery, are damaging sperm quality in men and domestic dogs.

The results of a new study involving both species form part of a growing body of research that seeks to understand why human male sperm quality has fallen by 50 percent in the past 80 years (see BioNews 911). The quality of domestic dog sperm has also declined by 30 percent, and it is now anticipated that dogs may be an effective model for future fertility research. 

'This new study supports our theory that the domestic dog is a sentinel or mirror for human male reproductive decline,' said study leader Professor Richard Lea at the University of Nottingham. 'Our findings suggest that chemicals used in the home may be responsible for the fall in sperm quality in both man and dog, who share the same environment.' 

Professor Lea's team tested the effects of two chemicals on sperm count and sperm quality from 11 men and nine dogs located in the same region, in identical experiments. Diethylhexyl phthalate (DEHP), is a substance added to products to increase plasticity or flexibility such as fabrics and children's toys. A type of polychlorinated biphenyl (PCB), known as PCB 153, was a chemical widely used in manufacturing, widely banned within the EU in 2004, but is still present in the environment and fatty foods. 

Previous research by Professor Lea showed that these chemicals were present in both wet and dry dog food.

The team discovered that human and dog sperm were affected in the same way when subjected to these chemicals at concentration levels found in the home environment. Significantly reduced sperm motility and increased levels of DNA fragmentation were observed, both of which are linked to male infertility. Sperm in both sample sets was slower and morphology was affected.

These results, published in Scientific Reports, support previous research indicating that chemicals exhibiting endocrine disrupting abilities affect the development and concentration of good quality sperm.

'Since environmental pollutants largely reflect a Western way of life, such as the effects of industry, the chemicals present in the environment are likely to depend on the location,' said Gary England, professor of veterinary reproduction at the University of Nottingham and a study co-author. 'An important area of future study is to determine how the region in which we live may effect sperm quality in both man and dog.'