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The article offers information on the contemporary and future challenges of historical legacies on dioxin. It states that it has long been identified that substantial PCDDs/PCDFs (dioxins) formation during industrial processes started in the beginning of the twentieth century with the chloro alkali process and the subsequent high volume production of organochlorines. Relative to this, it is just recently recognized that high levels of dioxin contamination may be associated to the industrial activities which took place before the 1900s. The "Stockholm Convention on Persistent Organic Pollutants (POPs)" has addressed this concern on dioxins.

From May to September 2005, five passive air samples were deployed over five, 1-month periods at five elevations on the CN Tower in Toronto, Canada, to investigate the vertical distribution, seasonality, and sources of organochlorine pesticides. A strong seasonality was observed between spring and the end of summer. Vertical profiles differed for different pesticide classes. For instance, α- and γ-hexachlorocyclohexane exhibited higher concentrations (60°80 pg m-3, respectively) near the ground during the spring and early summer, suggesting that surface-air exchange within the city or nearby Lake Ontario may be important sources. The vertical profile for chlordane isomers was variable, suggesting that both advective and local inputs are important. For dieldrin, no obvious trend with elevation was observed, suggesting that concentrations could reflect a regional air mass contamination. Strongest seasonality was observed for the endosulfans, a widely used pesticide in North America, that reached peak concentrations of 750–850 pg m-3 during June/July. Advective inputs of endosulfan from regional or more distant agricultural regions can explain the relatively uniform concentrations with elevation throughout the study period. The approach used in this study demonstrates that monthly average vertical concentration profiles differ between pesticide groups and reflect their use as well as the relative magnitude of input from local versus regional sources. [ABSTRACT FROM AUTHOR]

Pollution control in one environmental medium may alter polluters' releases into other media. This paper examines cross-media responses to public policies that restrict toxic air emissions and that increase waste management costs. The EPA's 1987-90 Toxic Release Inventories are used to study the policies' effects on air emissions and waste generation of chlorinated solvents. The results suggest that constraints on air emissions reduce waste generation, perhaps because facilities rely less on these chemicals. Increases in hazardous waste management costs increase air emissions, however, suggesting that facilities substitute between releases into different environmental media. [ABSTRACT FROM AUTHOR]