Giant hogweed sap + skin + sunlight = serious burns
If you see anything that looks like the plant above, don’t touch it, because it contains phototoxins that can cause third-degree burns if sunlight strikes your skin after being exposed to them.
Why are you telling me this NOW?
Because the plant has been spreading recently, accoridng to a Weather Channel story:
Sightings of the giant hogweed have been reported in Virginia, Maine, New York, Massachusetts, Connecticut, Pennsylvania, North Carolina and parts of the Pacific Northwest, WTVD reports.
What does it look like?
Biologist Yasmin Tayag explains:
One of the most dangerous things about giant hogweed is that it has a lot of lookalikes. Most similar is cow parsnip, a tall, mostly nontoxic herb with white bunches of flowers and lobed leaves. This plant is common across America, and touching it won’t leave sufficiently graphic burns on your body but may cause a rash.
But you’ll recognize giant hogweed by its size: It’s much taller, and its leaves are about five feet wide, with lobes deeply cut toward the stem. Its flower clusters are larger and has more flower rays, and its stems are covered in purple spots and stiff white hairs. Cow parsnip generally looks like a milder version of giant hogweed, with smaller clusters and leaves and softer, fewer white hairs.
Because the plants need to be removed by hand — and with a lot of protection — it’s best to stay away and leave it to local parks and wildlife officials to deal with.
What can happen if I touch it?
Isle of Wight County, Virginia, explains, via a Washington Post article:
Symptoms include painful blisters, which become darkly pigmented and can cause scars. Your skin can remain sensitive to sunlight for many years after exposure as well. And, if the sap gets in your eyes, there is the potential for blindness.
There are some nasty photos within that same WaPo article, if you care to look.
What should I do if I come in contact with it?
Back to our Weather Channel story:
If contact is made with the plant, immediately wash the affected area thoroughly with soap and water and keep the area away from sunlight for 48 hours, the agency recommends.
"This plant poses a serious health threat," the agency notes. "See your physician if you think you have been burned by giant hogweed. If you think you have giant hogweed on your property, do NOT touch it."
How does this photosensitizing thing work, anyway?
Giant hogweed is one of many plants that produce furocoumarins, or furanocoumarins. I found this blurb from the book Polyphenols in Human Health and Disease (2014):
Furanocoumarins appear to be responsible for the majority of phototoxic reactions in humans caused by plants. [...]
The phototoxic action of the furanocoumarins is due to their ability to react with nucleobases in DNA under the influence of UV-A radiation. On further exposure to UV-A radiation these adducts react with neighboring nucleobases giving rise to cross-links in DNA. The resulting interstrand cross-links in DNA lead to the characteristic acute bullous lesions.
I have to say, I have seen photosensitizers like this act on cultured cells upon exposure to light. Those cells are absolutely wiped out within hours. You don’t want this anywhere near you.