Pollutants that mimic human hormones, including dioxin have become ubiquitous in the environment and may be affecting births. For instance, in 1976, an industrial accident released high levels of dioxin into the environment near Seveso, Italy. Of the nine couples who received the highest exposure, 12 daughters were born--and no sons. Among four couples who had lower blood levels of dioxin, "The male-female ratio approached normal," said Larry L. Needham of the Atlanta CDC.
Devra Lee Davis, a program director at WRI believes that the declining male birth ratio "should be viewed as a sentinel health event," an indicator that environmental hazards difficult to detect by other means do exist and should be dealt with.
But there are other theories too. A study in the journal of the American Medical Association found that high exposures to certain pesticides could interfere with a father's ability to produce sperm cells with Y chromosomes--the kind needed for boys.
And, another study found that women who eat PCB-contaminated fish (PCBs, or polychlorinated biphenyls, can mimic female sex hormones) are less likely to give birth to boys. The women who were exposed to the highest levels of PCBs (just by eating contaminated fish) had about 50 percent fewer boys compared with women who had been exposed to the lowest levels.
Source: http://www.sixwise.com/newsletters/05/06/22/why-are-more-boys-than-girls-being-born.htm
Devra Lee Davis, a program director at WRI believes that the declining male birth ratio "should be viewed as a sentinel health event," an indicator that environmental hazards difficult to detect by other means do exist and should be dealt with.
But there are other theories too. A study in the journal of the American Medical Association found that high exposures to certain pesticides could interfere with a father's ability to produce sperm cells with Y chromosomes--the kind needed for boys.
And, another study found that women who eat PCB-contaminated fish (PCBs, or polychlorinated biphenyls, can mimic female sex hormones) are less likely to give birth to boys. The women who were exposed to the highest levels of PCBs (just by eating contaminated fish) had about 50 percent fewer boys compared with women who had been exposed to the lowest levels.
Source: http://www.sixwise.com/newsletters/05/06/22/why-are-more-boys-than-girls-being-born.htm