It's official: Men really are the weaker sex.

The male gender is in danger, with incalculable consequences for both humans and wildlife, startling scientific research from around the world reveals.

The research – to be detailed tomorrow in the most comprehensive report yet published – shows that a host of common chemicals is feminising males of every class of vertebrate animals, from fish to mammals, including people.

Backed by some of the world's leading scientists, who say that it "waves a red flag" for humanity and shows that evolution itself is being disrupted, the report comes out at a particularly sensitive time for ministers. On Wednesday, Britain will lead opposition to proposed new European controls on pesticides, many of which have been found to have "gender-bending" effects.

It also follows hard on the heels of new American research which shows that baby boys born to women exposed to widespread chemicals in pregnancy are born with smaller penises and feminised genitals.

"This research shows that the basic male tool kit is under threat," says Gwynne Lyons, a former government adviser on the health effects of chemicals, who wrote the report.

Wildlife and people have been exposed to more than 100,000 new chemicals in recent years, and the European Commission has admitted that 99 per cent of them are not adequately regulated. There is not even proper safety information on 85 per cent of them.

Many have been identified as "endocrine disrupters" – or gender-benders – because they interfere with hormones. These include phthalates, used in food wrapping, cosmetics and baby powders among other applications; flame retardants in furniture and electrical goods; PCBs, a now banned group of substances still widespread in food and the environment; and many pesticides.

The report – published by the charity CHEMTrust and drawing on more than 250 scientific studies from around the world – concentrates mainly on wildlife, identifying effects in species ranging from the polar bears of the Arctic to the eland of the South African plains, and from whales in the depths of the oceans to high-flying falcons and eagles.

It concludes: "Males of species from each of the main classes of vertebrate animals (including bony fish, amphibians, reptiles, birds and mammals) have been affected by chemicals in the environment.

"Feminisation of the males of numerous vertebrate species is now a widespread occurrence. All vertebrates have similar sex hormone receptors, which have been conserved in evolution. Therefore, observations in one species may serve to highlight pollution issues of concern for other vertebrates, including humans."

Fish, it says, are particularly affected by pollutants as they are immersed in them when they swim in contaminated water, taking them in not just in their food but through their gills and skin. They were among the first to show widespread gender-bending effects.

Half the male fish in British lowland rivers have been found to be developing eggs in their testes; in some stretches all male roaches have been found to be changing sex in this way. Female hormones – largely from the contraceptive pills which pass unaltered through sewage treatment – are partly responsible, while more than three-quarters of sewage works have been found also to be discharging demasculinising man-made chemicals. Feminising effects have now been discovered in a host of freshwater fish species as far away as Japan and Benin, in Africa, and in sea fish in the North Sea, the Mediterranean, Osaka Bay in Japan and Puget Sound on the US west coast.

Research at the University of Florida earlier this year found that 40 per cent of the male cane toads – a species so indestructible that it has become a plague in Australia – had become hermaphrodites in a heavily farmed part of the state, with another 20 per cent undergoing lesser feminisation. A similar link between farming and sex changes in northern leopard frogs has been revealed by Canadian research, adding to suspicions that pesticides may be to blame.

Male alligators exposed to pesticides in Florida have suffered from lower testosterone and higher oestrogen levels, abnormal testes, smaller penises and reproductive failures. Male snapping turtles have been found with female characteristics in the same state and around the Great Lakes, where wildlife has been found to be contaminated with more than 400 different chemicals. Male herring gulls and peregrine falcons have produced the female protein used to make egg yolks, while bald eagles have had difficulty reproducing in areas highly contaminated with chemicals.

Even more ominously for humanity, mammals have also been found to be widely affected.

Two-thirds of male Sitka black-tailed deer in Alaska have been found to have undescended testes and deformed antler growth, and roughly the same proportion of white-tailed deer in Montana were discovered to have genital abnormalities.

In South Africa, eland have been revealed to have damaged testicles while being contaminated by high levels of gender-bender chemicals, and striped mice from one polluted nature reserved were discovered to be producing no sperm at all.

At the other end of the world, hermaphrodite polar bears – with penises and vaginas – have been discovered and gender-benders have been found to reduce sperm counts and penis lengths in those that remained male. Many of the small, endangered populations of Florida panthers have been found to have abnormal sperm.

Other research has revealed otters from polluted areas with smaller testicles and mink exposed to PCBs with shorter penises. Beluga whales in Canada's St Lawrence estuary and killer whales off its north-west coast – two of the wildlife populations most contaminated by PCBs – are reproducing poorly, as are exposed porpoises, seals and dolphins.

Scientists warned yesterday that the mass of evidence added up to a grave warning for both wildlife and humans. Professor Charles Tyler, an expert on endocrine disrupters at the University of Exeter, says that the evidence in the report "set off alarm bells". Whole wildlife populations could be at risk, he said, because their gene pool would be reduced, making them less able to withstand disease and putting them at risk from hazards such as global warming.

Dr Pete Myers, chief scientist at Environmental Health Sciences, one of the world's foremost authorities on gender-bender chemicals, added: "We have thrown 100, 000 chemicals against a finely balanced hormone system, so it's not surprising that we are seeing some serious results. It is leading to the most rapid pace of evolution in the history of the world.

Professor Lou Gillette of Florida University, one of the most respected academics in the field, warned that the report waved "a large red flag" at humanity. He said: "If we are seeing problems in wildlife, we can be concerned that something similar is happening to a proportion of human males"

Indeed, new research at the University of Rochester in New York state shows that boys born to mothers with raised levels of phthalates were more likely to have smaller penises and undescended testicles. They also had a shorter distance between their anus and genitalia, a classic sign of feminisation. And a study at Rotterdam's Erasmus University showed that boys whose mothers had been exposed to PCBs grew up wanting to play with dolls and tea sets rather than with traditionally male toys.

Communities heavily polluted with gender-benders in Canada, Russia and Italy have given birth to twice as many girls than boys, which may offer a clue to the reason for a mysterious shift in sex ratios worldwide. Normally 106 boys are born for every 100 girls, but the ratio is slipping. It is calculated that 250,000 babies who would have been boys have been born as girls instead in the US and Japan alone.

And sperm counts are dropping precipitously. Studies in more than 20 countries have shown that they have dropped from 150 million per millilitre of sperm fluid to 60 million over 50 years. (Hamsters produce nearly three times as much, at 160 million.) Professor Nil Basu of Michigan University says that this adds up to "pretty compelling evidence for effects in humans".

But Britain has long sought to water down EU attempts to control gender-bender chemicals and has been leading opposition to a new regulation that would ban pesticides shown to have endocrine-disrupting effects. Almost all the other European countries back it, but ministers – backed by their counterparts from Ireland and Romania – are intent on continuing their resistance at a crucial meeting on Wednesday. They say the regulation would cause a collapse of agriculture in the UK, but environmentalists retort that this is nonsense because the regulation has get-out clauses that could be used by British farmers.