Are Boys An Endangered Species?

Half as many boys as girls are being born in some places around the world—and pollution is the prime suspect.

Among the Chippewas of the Aamjiwnaang First Nation community living on the shores of the St. Clair River outside Sarnia, Ontario, tribal leaders were puzzling over a variety of health problems—from asthma to cancer to miscarriages—plaguing their families. The Aamjiwnaang—the name means “at the spawning stream”—were shaken when they realized that there was a dramatic disproportion of girls to boys among them.

Jim Brophy, director of the Occupational Health Clinic for Ontario Workers’ Sarnia branch, remembers the look of shock on their faces when they suddenly made the connection. “It was like a deep family secret getting out,” Brophy recalls. “They had enough girls for three baseball teams, but not enough boys for even one boy team.”

Since then, the Chippewas of Aamjiwnaang’s 850 band members—who live near a cluster of chemical plants known as Chemical Valley—have worried that the air and water around them contribute to the drop in the number of their male children, as well as a host of grim diseases associated with toxic chemicals.

And now, in a number of villages at the northernmost reaches of the Arctic Circle—seemingly remote from any hazardous chemicals—scientists have found a similar syndrome: populations spawning twice as many girls as boys. Based on preliminary data released in September 2007, researchers are blaming high levels of man-made chemicals that have made their way up the food chain, through fish and other marine species, and into indigenous seafood diets. 

Indigenous Arctic peoples show high levels of chemical contamination, researchers say, because they depend on local fish, marine animals, seabirds and reindeer meat, which are significantly more contaminated than imported food by persistent organic pollutants like PCBs, dioxin and DDT.

So far, researchers from the Arctic Monitoring and Assessment Programme have linked the dramatically skewed declines in male baby births with chemical contamination. But they haven’t determined the exact biological mechanisms by which these changes are taking place.

However, according to Lars-Otto Reiersen, executive secretary of AMAP in Oslo, Norway, “PCBs, DDTs and other persistent organic pollutants are known from research to possibly trigger male and female hormone signals incorrectly.”

These strange and disturbing cases are by no means the only ones providing clues that there can be changes to the sex ratio—the normal, and usually fairly even, proportion of male to female live births. One of the first examples of this phenomenon came when thousands of people were contaminated by dioxin in a 1976 industrial accident at a chemical factory in Seveso, Italy. After the accident, researchers followed the children of the people affected to discover that half the number of boys as girls were born in the next generation.

Lars-Otto Reiersen and other Arctic researchers fear the same thing could be happening in the Russian Arctic.  “Arctic indigenous populations, whose lifestyle is based on the consumption of traditional country foods, are subject to some of the highest exposure levels to PTS (persistent toxic substances) of any population groups on Earth,” according to the AMAP report.

Also alarming is the decline in male births around the world, a trend some scientists find troubling. In the United States, more boys are being born than girls, but the gap between the two has declined in the last 30 years.

> Talk About It: What Do You Think About Boys as an Endangered Species?