The Consumer Product Safety Commission has defended its record on ridding the market of dangerous toys but is urging parents to consider safety when shopping for their children this holiday season. The commission said Tuesday that its joint effort with the U.S. Customs Service has resulted in the seizure of 891,000 toys that failed to meet federal safety guidelines between Oct. 1, 1987 and Sept. 30, 1988, and 162,668 toys since Oct. 1 of this year. But commission officials urged parents to heed the age recommendations and warning labels on toys.