Delegates from 127 countries yesterday formally moved to adopt a treaty to ban or reduce the use of 12 persistent organic pollutants (POPs), chemicals such as PCBs and pesticides that have been linked to cancer, birth defects, and genetic abnormalities in humans and wildlife. The treaty will be signed by delegates in Stockholm, Sweden, today, but it still must be ratified by at least 50 governments to take effect, a process that could take several years. Canada became the first country to ratify the treaty today. The gathering in Stockholm hasn’t been as cheery as one might expect, as European Union officials have continued to criticize the U.S. for backing out of the Kyoto treaty on climate change and for pursuing an energy plan that promotes increased use of coal and oil.