Risk assessments should consider chemical mixtures rather than individual substances, Chemtrust says (ENDS Report 411, p 45 ). Currently, several phthatlate plasticisers implicated in male reproductive problems are being considered individually for authorisation under the EU’s REACH chemicals regime.
Over the past 60 years, testicular cancer, undescended testes and hypospadias, where the urethral opening is on the underside of the penis, appear to have been on the rise in western countries, while sperm counts are falling.
The speed of change suggests environmental factors such as lifestyle or chemical exposure are the cause, the report says. These health problems described collectively as testicular dysgenesis syndrome are thought to be linked, and may be caused by disrupted male development during pregnancy.
Testicular dysgenesis can be induced in laboratory animals by exposing them to endocrine-disrupting chemicals such as phthalates and certain pesticides. Chemical mixtures at low doses that are individually inactive can act together to cause a cocktail effect (ENDS Report 404, p 28 ).
But there are practical and ethical obstacles to proving cause and effect in humans the authors say. The report concludes "data suggest that exposure to environmental chemical mixtures probably accounts for a proportion of cases of cryptorchidism [undescended testes] and hypospadias".
It was written by Professor Richard Sharpe of the Medical Research Council’s Human Reproductive Sciences Unit in Edinburgh.