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. 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.