xenobiotic
Concise Oxford English Dictionary © 2008 Oxford University Press:
xenobiotic /ˌzɛnə(ʊ)bʌɪˈɒtɪk/
▶adjective relating to or denoting a substance that is foreign to the body or to an ecological system. ▶noun a substance of this kind.
'xenobiotic' also found in these Oxford entries:

