direct carcinogen

例句：

1. 1. The studyfound that exposure to certain chemicals can bea direct carcinogen for humans.
   研究发现，某些化学物质对人类来说可能是直接致癌物。
2. 2. The government has banned the sale ofsome products that are known to be directcarcinogens.
   政府已经禁止销售一些已知的直接致癌产品。
3. 3. The researcher warned that exposure to these substancescould increase the risk of developing cancer.
   研究人员警告说，暴露于这些物质可能会增加患癌症的风险。