President Bush said yesterday he supports a clean environment, but would “make decisions based upon sound science, not some environmental fad or what may sound good.” He defended his environmental record at an environmental awards ceremony for youths, and he continued to talk green in interviews aired this morning on network shows. Since becoming president, Bush has broken a campaign promise to regulate carbon-dioxide emissions, ended U.S. participation in the Kyoto treaty on climate change, canned a rule to lower arsenic levels in drinking water, slashed a rule to make air conditioners more efficient, and rescinded a plan to make sure mining companies clean up after themselves. Yesterday, he said his biggest mistake since taking office was “allowing people to define me as somebody who’s not friendly toward the environment.” On ABC’s “Good Morning America,” Bush said, “Somehow I got tagged for not wanting to reduce arsenic in drinking water.”