外源物质 meaning in English

foreign matter

Effect of exogenous materials on cotton fiber strength development in low temperature conditions
低温条件下外源物质对棉纤维比强度的影响
Beer is a safe product where foreign bodies and chemicals may contaminate it at various stages within the process
摘要啤酒作为一种安全食品，在其加工的各个阶段都有可能受到外源物质和化学物质的侵扰。
It is also demonstrated in the field trials that some exotic substance have substantial influence on as uptaking by pteris vittata , indicating the significance of applying proper chemicals into the soil to be remidiated in improving remediation efficiency
研究表明，不同地域生长的蜈蚣草外形指标和砷富集能力存在着很大的差异；另外，一些外源物质也影响蜈蚣草对砷的吸收，添加外源物质是提高蜈蚣草砷污染土壤修复效率的一个有效措施。