Wear a dust mask

Old stone or cement walls - especially caulking from the Sixties and Seventies - can release dangerous levels of PCBs when pulverised. As you breathe in, your testes can deflate.

Avoid sex toys and fishing lures

Gelled rubber - which makes fake worms and vibrators squishy - contains phthalates that can enter the body, decreasing semen quality in men. To be safe, switch to real worms in fishing; fingers and tongue during sex.

Toss old lawn treatments

In 2002, the US Environmental Protection Agency banned the sale of residential products with chlorpyrifos, an organophosphate proved to reduce testosterone in men. Time to dispose of (properly) the old weed killer. Industrial use is still okay; pay heed if the sign says: "Keep off the grass!"

Protect the pregnant

Women exposed to endocrine disruptors like PCBs, dioxins and phthalates give birth to male babies with higher rates of birth defects like cryptorchidism (undescended testicles), hypospadias (malformation of the penis) and testicular cancer.

Buy a new bike seat

Narrow seats put pressure on your perineum, causing erectile dysfunction. Buy a seat that transfers pressure onto your hip bones during practice rides and save the narrow saddle for race day.

Shop at the organic market

Pesticides are like debt: a little a day, over time, can develop into a big problem. Sidestep these testosterone killers by buying organic produce or growing your own testicle-friendly garden.

Read the ingredients list

A small study has shown a connection between lavender and tea-tree oils in cosmetics and the development of breast tissue in boys. Avoidance may be the best policy for now.