extrinsic allergen

例句：

1. 1. Extrinsic allergens are the substances that trigger allergies in people with a genetic predisposition to them.
   外因过敏原是那些在有遗传倾向的人中引发过敏的物质。
2. 2.The study found that exposure to certain extrinsic allergens could increase the risk of developing allergies.
   研究发现，暴露于某些外因过敏原可能会增加患过敏性疾病的风险。
3. 3. Researchers have identified several extrinsic allergens that can trigger asthma attacks in children.
   研究人员已经确定了几种外因过敏原，可以触发儿童哮喘发作。