Shredded Poison Ivy – Losing Potency

Q: I read your online article that said it takes about one week for urushiol (the oil in poison ivy) to lose its potency or cause a reaction in hot and humid places, like a composting facility. How long does it take for shredded leaves to lose their potency in normal outdoor conditions? 

A: I was wrong! I forgot that urushiol is an oil and is not easily dissolved by water. The water will wash it away eventually but it will take a long time without the help of another solvent. Effective solvents for oils include alcohol and hot soapy water. Even in a compost pile, urushiol can cause irritation in sensitive individuals for up to a year. In your lawn urushiol will be broken down by sunshine but not much else. Shredded leaves would compost in about a month but the urushiol would still be nearby. Bottom line: be cautious wherever you encounter poison ivy and don’t let the oil touch your skin.

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