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[Dioxin
pollution leads to more baby girls -study
Thu Oct 18,
2007
http://www.reuters.com/article/healthNews/idUSN1836384520071018 [Please visit the original website to view the whole article.] By Jonathan Spicer TORONTO (Reuters) - More girls than boys are born in some Canadian communities because airborne pollutants called dioxins can alter normal sex ratios, even if the source of the pollution is many kilometers away, researchers say. Dioxin exposure has been shown elsewhere to lead to both higher cancer rates and the birth of more females. Researchers at the IntrAmericas Centre for Environment and Health say their findings, released this month, confirm the phenomenon in Canada. The study also reveals the health risks of living within 25 km (15.5 miles) of sources of pollution -- a greater distance than previously thought, they said. Normally, 51 percent of births are boys and 49 percent are girls. But the ratio was reversed -- with as few as 46 males born for every 54 females -- in Canadian cities and towns where parents were exposed to pollutants from sources such as oil refineries, paper mills and metal smelters, according to the study. "If you find an inverted sex ratio, and want to know what causes it, look for sources of dioxin," said James Argo, a medical geographer who headed the study, which was published in a journal of the American Chemical Society. "In every one of those cities where those industries are found ... there was a higher probability of female births to male births," Argo said in an interview. Using birth data and an inventory of pollution sources, the study also concluded that early exposure to dioxins -- even at 25 km away from the source -- increased the risk of cancer later in life in a group of 20,000 people surveyed during the 1990s. Previous studies that linked dioxins with cancer and a gender imbalance focused on smaller distances, usually about 5 km, Argo said. ... = -- = -- = -- Excess female to male births in Canada linked to chronic dioxin exposure Environmental Science & Technology http://www.eurekalert.org/pub_releases/2007-10/acs-acs101607.php Almost 90 Canadian communities have experienced a shift in the normal 51:49 ratio of male to female births, so that more girls than boys are being born, according to two studies in the Oct. 1 issue of ACS' Environmental Science & Technology, a semi-monthly journal. James Argo, who headed the research, attributes this so-called "inverted sex ratio" of the residents in those communities to dioxin air pollutants from oil refineries, paper mills, metal smelters and other sources. The studies analyzed information in the Environmental Quality Database (EQDB), an inventory of pollution sources, cancer data, and other factors developed for Canadian government research on how early exposure to environmental contaminants affects the health of Canadians. Argo points out that the EQDB enables researchers to pinpoint the location of 126,000 homes relative to any of about 65 air pollution sources-types and the occurrence of cancer among residents of those homes. Argo focused on air pollutants from those sources and the corresponding incidence of cancer among more than 20,000 residents and 5,000 controls. He identified inverted male sex ratios, sometimes as profound as 46:54 in almost all of the communities. The ratio indicated that more females than males were born, a situation that Argo attributed to chronic exposure of parents to dioxin, based on previous studies. The study "may represent one of only a few studies explicitly designed to identify the impact of carcinogens from industrial sources on residents at home," Agro stated. "Chronic Disease and Early Exposure to Air-Borne Mixtures: 1. The Environmental Quality Database" and "Chronic Disease and Early Exposure to Air-Borne Mixtures: 2. Exposure Assessment" http://pubs.acs.org/cgi-bin/sample.cgi/esthag/2007/41/i20/pdf/es071354u. pdf CONTACT: James Argo, Ph.D. IntrAmericas Centre for Environment and Health Ontario, Canada Phone: 613-385-1831 Fax: 613-385-1832 E-mail: iceh@kos.net |