The claim: Wild parsnips can cause skin blisters, harmful to humans
Planning a hike or a nature walk? You probably know to avoid poison ivy by its distinguishable three leaves on a single stem or stinging nettle by its tiny hair-like projections. But there may be one seemingly innocuous plant not on your radar, as one Facebook post claims.
"(It's) about that time of the year again and we are terrified of the kids coming into contact with Wild Parsnip. Please, please be aware of how dangerous this plant really is!" claims the May 31, 2019, post, since shared over 142,000 times on the social media platform.
The poster says the yellow flowering plant, resembling an upturned umbrella in accompanying pictures, produces a sap that reacts violently with skin after exposure to sunlight, causing blisters, burns and potentially blindness.
Large, fluid-filled blisters on the chest, hands and arms of an unidentified child, purportedly the poster's son, are included, emphasizing the need for awareness and caution.
"I have heard about Wild Parsnip but never knew it was this bad. Poor little guy," commented one Facebook user.
"Oh my gosh, (I) had this in the field behind my house last year, wonder if it comes back every year," said another.
Wild parsnip, an invasive plant species from Europe and Asia likely brought by European settlers to North America for its edible root, is a widespread problem in Canada and in states like Ohio, New York and Minnesota. USA TODAY cannot verify the images shared in the post, but its word of warning about the plant is indeed scientifically true.
Sap contains chemicals that react with sunlight
Standing at almost 5-feet tall with a single, deeply ridged stem about 2- to 5-centimeters thick, wild parsnip is found throughout southern Canada and the northern U.S. All parts of the plant – from the stems, leaves and flowers – contain phytochemicals called psoralens, which kill skin cells by inserting themselves into our DNA.
Normally, our skin shields us from a type of radiation emitted by the sun called long-wave ultraviolet radiation, or LWUVR. But with psoralens essentially hijacking our genetic code, they boost the amount of LWUVR our skin absorbs and stop cellular growth.
This may sound bad, and does result in a condition called phytophotodermatitis characterized by angry-looking blisters and burn-like symptoms, but psoralens in combination with ultraviolet light therapy have been used to safely treat skin diseases like psoriasis and vitiligo since the 1970s.
Other conditions resulting from coming into contact with wild parsnip can include blindness if the sap gets into your eyes.
Wild parsnip grows in a whole range of environments but is commonly found along roadsides, pastures, abandoned fields and any place where soil has been disturbed and native vegetation has yet to be established, according to the New York Invasive Species Information Clearinghouse.
It's advised if you do come into contact with the yellow-flowered plant to get out of the sun as soon as possible or immediately cover the affected areas before washing with warm water and soap. While photosensitivity and discoloration typically last up to eight hours, these symptoms can linger for up to two years.
Our rating: True
Based on our research, we rate TRUE the claim wild parsnip sap can cause skin blisters. A phytochemical secreted by wild parsnip, called psoralens, reacts when exposed to sunlight, affecting cell growth, which results in blisters, other burn-like symptoms and even blindness if the sap gets in the eyes.
Our fact-check sources:
American Hiking Society, accessed June 22, Plant Safety
Ontario.gov, May 21, Wild parsnip
The Columbus Dispatch, June 22, You've met COVID-19 and cicadas. Don't forget about poison hemlock and wild parsnip
University of Wisconsin Extension via YouTube, July 26, 2011, Wild Parsnip, Identification of the Wisconsin Invasive Species Pastinaca sativa
Ohio State University, May 15, 2019, Be Alert to Wild Parsnip!
WebMD, Feb. 24, 2020, What Are Psoralens?
Medscape, Sept. 12, 2019, Phytophotodermatitis
Dermatology and Therapy, July 29, 2016, The Patient's Guide to Psoriasis Treatment. Part 2: PUVA Phototherapy
CBC, July 19, 2018, Regina man left with 'huge blisters' after run-in with wild parsnip
The Kingston Whig Standard, July 10, 2015, Wild parsnip blamed for dog's burns
New York Invasive Species (IS) Information, July 5, 2019, Wild Parsnip
Cornell University Weed Identification, accessed June 22, Wild Parsnip
Healthline, Dec. 3, 2019, Wild Parsnip Burns: Symptoms, Treatment, and How to Avoid
Thank you for supporting our journalism. You can subscribe to our print edition, ad-free app or electronic newspaper replica here.
Our fact check work is supported in part by a grant from Facebook.
This article originally appeared on USA TODAY: Fact check: Contact with wild parsnip a danger to humans and animals