noun
fumigant
A chemical agent used for fumigation, typically in agriculture, pest control, or quarantine.
輸入木材には燻蒸剤が使われることがある。
Fumigants are sometimes used on imported timber.
燻蒸 is the process of fumigation; 燻蒸剤 is the substance used for it.
Compound of 燻蒸 (kunjo, 'fumigation') + 剤 (zai, 'agent, chemical'). The exact historical derivation is uncertain, but the term is a modern technical coinage.