Umweltgifte führen zum Rückgang männlicher Geburten

Intrauterin sind Knaben empfindlicher als Mädchen!

In den Industrieländern werden zunehmend weniger Jungen als Mädchen geboren. Eine Studie in Environmental Health Perspectives (2007; doi 10.1289/ehp9540) zeigt für die USA und Japan eine seit den 1970er-Jahren anhaltende Entwicklung, für die Umweltfaktoren verantwortlich sind.

In den USA kommen heute auf 10.000 Geburten 17 Jungen weniger als vor drei Jahrzehnten. In Japan kam es sogar wesentlich weniger.

mehr beim Deutschen Ärzteblatt 12.04.2007 

Oder auch:

The Independet
18 September 2007 23:38

Toxic chemicals blamed for the disappearance of Arctic boys
By Daniel Howden in Nuuk, Greenland
Published: 12 September 2007

Twice as many girls as boys are being born in remote communities north of the Arctic Circle. Across much of the northern hemisphere, particularly in the US and Japan, the gender ratio has skewed towards girls for the first time.

Now scientists working with Inuit villages in Arctic Russia and Greenland have found the first direct evidence that this trend is linked to widespread chemical pollutants. Despite the Arctic's pristine environment, the area functions as a pollution sink for much of the industrialised world. Winds and rivers deliver a toxic tide from the northern hemisphere into the polar food chain.

Scientists have traced flame-retardant chemicals used in everything from industrial products to furniture, phones and laptops to the food chain, finding high levels of these pollutants in seabirds, seals and polar bears. The Inuit have traditionally relied on a hunter- gatherer's diet almost exclusively made up of marine animals, making them especially vulnerable to toxic pollutants.

Historically in large populations, it is considered normal for the number of baby boys slightly to outnumber girls in a trend believed to compensate naturally for greater male mortality rates.

But a peer-reviewed US study found an unexpected drop in the proportion of boys born in much of the northern hemisphere. The missing boys would number more than 250,000 in the US and Japan, using the gender ratio at the levels recorded up until 1970.

The researchers suspect-ed that this linked widespread exposure among pregnant women to hormone-mimicking pollutants. But Danish scientists examined 480 families in the Russian Arctic and found high levels of the hormone-mimicking pollutants in the blood of pregnant women, and twice as many girls being born as boys.

They are now studying similar communities in Greenland and Canada and although full results will be published next year, their initial findings exactly match those in Russia.

Lars Otto Riersen, a marine biologist, pollution expert and an executive with the Arctic Monitoring and Assessment Programme (Amap), says: "When you see such things happening in the Arctic, it may happen here first, in the same way as climate change did."

Although the nature of the Inuit diet is believed to have triggered the disturbing ratios in the Arctic, a similar pattern may be emerging further south. Until now, the only evidence of the impact of these toxins was circumstantial. The most skewed ratio had been in Canada, where a First Nation community in Sarnia lives amid Ontario's petrochemical industry, and the number of boys born has plunged since the 1990s. The fallout from the toxic cloud in Seveso in Italy in 1976 allowed scientists to monitor dramatic impacts on both the gender ratios and numbers of babies born.

Every year in the industrialised world, household fires cause billions of pounds worth of damage, and chemical flame retardants designed to curb this are big business. They contain a host of chemicals some of which mimic human hormones. These chemicals became notorious in the 1960s and a worldwide ban on one category, PCBs, was introduced after tests showed they had entered the food chain with potentially lethal consequences for humans and animals. But the chemicals industry continues to produce variations of the retardants, which scientists claim are not subject to the long-range testing required.

Dr Jens Hansen, leader of Amap research, said they were finding incredibly high levels of banned PCBs among a cocktail of other hormone-mimicking chemicals in pre-natal mothers. Pregnant mothers, he said were ingesting these hormone-mimicking chemicals in their diet and passing them through the placenta where they influenced the gender of the foetus or killed male foetuses.

Aleqa Hammond, Greenland's Foreign Minister, says: "We heard from scientists four years ago that our heavy metal consumption is dangerous." She adds wryly: "If you ate me, you would die."

Aqqaluk Lynge, head of the Inuit Circumpolar Council, said they were trying to raise the alarm internationally but nobody was listening. "People don't want to talk about such a critical question. We are talking about our people's survival which is very alarming."

Greenland, the world's largest island and still a dependency of Denmark, now has the highest proportion of women in the world.