Chemicals used in common household products that leach into the environment are having a feminizing effect on male wildlife, warns a new study, which suggests potential harm to human males as well.

The report found that chemicals such as pesticides and phthalates block the male hormone androgen, which results in changes to male sex organs.

Phthalates are used in a number of plastic products, such as shower curtains, to make them more flexible.

The findings were released Sunday by CHEM Trust, an organization devoted to researching the effects of chemicals on both humans and animals.

The effects of anti-androgen chemicals include:

  • un-descended, small or abnormal testicles
  • small penises
  • ambiguous genitals

The effects are seen across a wide array of wildlife, from otters and seals in the United Kingdom to polar bears in the Arctic to eland antelopes in Africa, the report said.

As well, in egg-laying species, including fish, amphibians, birds and reptiles, males exposed to sex hormone-disrupting chemicals are producing an egg yolk protein normally made by females.

Affected species include flounder in U.K. estuaries, cod in the North Sea, cane toads in Florida, peregrine falcons in Spain and turtles in the Great Lakes.

These changes to male reproductive organs could decimate animal populations if factors such as fertility and sex drive are affected. Indeed, seal populations in the North Sea off eastern England have decreased so much that scientists there will soon begin investigating changes to the animals' reproductive health, according to the report.

"Urgent action is needed to control gender bending chemicals, and more resources are needed for monitoring wildlife," report author Gwynne Lyons said in a statement. "Man-made chemicals are clearly damaging the basic male tool-kit. If wildlife populations crash, it will be too late. Unless enough males contribute to the next generation, there is a real threat to animal populations in the long term."

Vertebrate animals have similar sex-hormone receptors, the report said.

"Therefore, observations in one vertebrate wildlife species, may serve to highlight pollution issues of concern for other vertebrates, including humans," the report said. "Indeed, given the widespread presence of endocrine (hormone) disrupting chemicals in the environment, effects are likely to be occurring in more species than those currently reported."

The report underscores growing concerns among scientists and the general public over the potential health effects caused by the chemical bisphenol A (BPA).

Numerous animal studies have shown that BPA mimics the effects of the hormone estrogen in the body. The chemical, found in a number of household products from plastic food containers and aluminum food cans to electronic equipment, is linked to health problems that range from reproductive difficulties to cancer and heart disease.

The findings have led the Canadian government to declare BPA a dangerous a substance and ban it from the manufacture of baby bottles.

The report also adds to growing research that shows babies born to mothers who are exposed to phthalates while pregnant are born with genital defects that include having a urinary tract separate from the penis and small or un-descended testicles.