New evidence supports the argument that high exposure to agrochemicals may affect sperm volume and quality.

A French study looked at 225 men from the Litoral Sur farming region of Argentina attending their first infertility consultation between 1995 and 1998. The investigators examined lifestyle, occupation, clinical history and, crucially, environmental exposure to chemicals. They found that the men with the highest exposure to chemicals such as pesticides and solvents tended to have lower sperm quantity and quality.

They also found that these chemicals tended to have a greater adverse effect on men who had never had children compared with those who had. This may be the result of the relatively recent (since the 1940s) introduction of pesticides to Argentina. Damage to sperm may be most devastating when men are exposed to these chemicals from birth.

Environmental factors like heat, herbicides, environmental oestrogens, dry cleaning agents and medications (some antihypertensives, chemotherapy agents and St John's wort) may have a harmful effect on male fertility. What has not yet been determined is why not all men react the same way to the same environmental toxins (Hum Reprod, 2001; 16: 1768-76).