Poison ivy, poison oak and poison sumac — to know them is to dread them. Just a moment's contact can lead to days or weeks of itchy misery. But soon there may be a spray available that makes the oily resin of these plants visible, helping people avoid getting it on their skin and saving them from all that misery.
Urushiol usually needs to be washed off in 5-10 minutes to prevent a reaction, but washing it off later on can still help reduce the severity of the rash.
Over half the people in the country are allergic to urushiol, the toxic oil produced by these poisonous plants. It takes only about 1/25 of a drop of urushiol on the skin to trigger a reaction that leads to an extremely annoying rash. And urushiol isn't only on the plants' leaves; it's found on all parts of the plant, so even in winter, brushing against the leafless stems or vines can cause a rash.
Researchers at the University of California Santa Cruz have developed a spray that makes urushiol glow when a handheld fluorescent light is shined on it. This can reveal the oil lurking on garden tools, clothing or even the fur of cats and dogs, saving people who live near or venture around these poisonous plants a lot of grief. They could then wash the oil off before it gets on their skin.
For those interested in the chemical details, the spray produces a boron derivative of urushiol, which then reacts with a pre-fluorescent nitro compound to produce a final fluorescent compound, one that will glow under ordinary fluorescent light. The spray may also prove useful in the detection of catecholamines, biologically important neurotransmitters.
The traditional way to avoid poison ivy and poison oak is by heeding the adage "leaves of three, let it be," since the leaves of poison ivy and poison oak grow as clusters of three leaflets. This isn't very helpful in the dark. And poison sumac grows in clusters of 7-13 leaflets. For the mathematically or botanically challenged, a spray that reveals urushiol-containing plants will probably be a lot simpler.
An article on the spray was published in the Journal of Organic Chemistry.