December 8, 2008
Could Males Really Become The Weaker Sex?
Scientific research from around the world suggests that the male gender is in danger, with incalculable consequences for both humans and wildlife.
The research shows that a host of common chemicals is feminizing males of every class of vertebrate animals, from fish to mammals, including people.On Wednesday, Britain will lead opposition to proposed new European controls on pesticides, many of which have been found to have "gender-bending" effects.
Recent U.S. research has also shown that baby boys born to women exposed to widespread chemicals in pregnancy are born with smaller penises and feminized genitals.
The basic male tool kit is under threat, according to the report's author, Gwynne Lyons, a former government adviser on the health effects of chemicals.
The European Commission said that wildlife and people have been exposed to more than 100,000 new chemicals in recent years and 99 per cent of them are not adequately regulated. There is not even proper safety information on 85 percent of them.
The majority of these chemicals 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 is based on more than 250 scientific studies from around the world and concentrates mainly on wildlife.
So far it has identified 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.
"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.
"Feminization 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."
Pollutants particularly affect fish as they are immersed in them when they swim in contaminated water, taking them in not just in their food but also through their gills and skin. They were among the first to show widespread gender-bending effects.
Earlier this year, researchers at the University of Florida found that 40 percent of 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 percent undergoing lesser feminization.
Canadian researchers noticed a similar link between farming and sex changes in northern leopard frogs, adding to suspicions that pesticides may be to blame.
Male alligators exposed to pesticides in Florida have suffered from lower testosterone and higher estrogen levels, abnormal testes, smaller penises and reproductive failures.
Similarly, male snapping turtles have been found with female characteristics in the same state and around the Great Lakes, where wildlife has been 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.
Mammal species' have been showing the signs as well.
Around 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 shown 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.
In the north, 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.
Researchers have also revealed otters from polluted areas with smaller testicles and mink exposed to PCBs with shorter penises. Beluga whales and killer whales, two of the wildlife populations most contaminated by PCBs, are reproducing poorly, as are exposed porpoises, seals and dolphins.
Professor Charles Tyler, an expert on endocrine disrupters at the University of Exeter, says that the evidence in the report "set off alarm bells". He suggests that whole wildlife populations could be at risk 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.
"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," said Dr. Pete Myers, chief scientist at Environmental Health Sciences.
Professor Lou Gillette of Florida University, one of the most respected academics in the field, warned that if we are seeing problems in wildlife, we should be concerned that something similar is happening to a proportion of human males.
Researchers at the University of Rochester showed 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 feminization.
Another study from 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.
In a mysterious shift in sex ratios worldwide, areas 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.
Typically 106 boys are born for every 100 girls, but the ratio is lowering. It is calculated that 250,000 babies who would have been boys have been born as girls instead in the US and Japan alone.
Studies in more than 20 countries have shown that sperm counts in men have dropped from 150 million per milliliter of sperm fluid to 60 million over 50 years.
Professor Nil Basu of Michigan University says that this adds up to "pretty compelling evidence for effects in humans".
Officials in Britain have long sought to water down EU attempts to control gender-bender chemicals and have been leading opposition to a new regulation that would ban pesticides shown to have endocrine-disrupting effects.
The majority of the other European countries back the suggested bans, but ministers from Ireland and Romania are intent on continuing their resistance, arguing that the regulation would cause a collapse of agriculture in the UK.
However, environmentalists maintain that this is nonsense because the regulation has get-out clauses that could be used by British farmers.