The U.S. Department of Commerce has reached a preliminary decision to impose up to 65.72 percent anti-dumping tariffs on certain chemical materials from South Korea, Seoul's industry ministry said Friday. On Wednesday (U.S. time), the department announced its preliminary affirmative determination to impose anti-dumping duties between 10.94 percent and 65.72 percent on two Korean companies exporting monomers and oligomers to the United States, according to the Ministry of Trade, Industry and Resources. The decision came about six months after Washington initiated a dumping investigation into certain monomers and oligomers from Korea and Taiwan at the request of a U.S. chemical producer. The preliminary margins represent a significant reduction compared with the 137 percent to 188 percent dumping margins originally alleged by the petitioner, according to the ministry. The ministry said it will closely communicate with the companies to ensure they do not face unfair treatment in the U.S. department's final ruling in May.