Threat of wild parsnip in Ottawa overblown: experts

An environmental expert and botanist are scratching their heads over the City of Ottawa’s recent frenzy to rid the region of Pastinaca sativa, also known as wild parsnip.

Wild parsnip, which grows in every part of Canada but Nunavut, is particularly abundant in Southern and Eastern Ontario. The tall, yellow flowering plant is thought to have been brought to Canada in the 1600’s by European settlers who cultivated it for its edible root.

However, like many plants — including figs, celery, parsley, oranges, lemons and limes — it contains an organic chemical compound called psoralen. When the psoralen in the plant’s sap makes contact with bare skin and UV light, it can cause phytophotodermatitis and a chemical reaction that causes the skin to sting, redden, blister and burn.

In the years since wild parsnip was introduced, the plants escaped cultivated gardens and spread widely across the continent. Wild parsnip can grow as tall as 1.5 metres and is usually found in patches or as scattered plants on roadsides, pastures, parks and sports fields.

Recently added to Ontario’s Noxious Weed list, this spring the City of Ottawa announced a campaign to battle the plant and says it has sprayed more than 250 kilometres of roadside and city parks with Clearview and Truvist herbicides.

With $100,000 earmarked for its destruction on municipal property, the city is asking anyone who sees a wild parsnip plant to call 311 or use an online reporting form.

This, says environmental consultant Dan Brunton, is ridiculous. He believes that a lack of information and due diligence has municipalities and city public works targeting the wrong plant.

“They haven’t done their homework. There is a really nasty plant in the same family called giant hogweed and this thing’s a monster, it gets ten feet tall, it’s covered in giant needles and it has really nasty toxic juices that will blister your skin. There have been reports of people going blind after coming into contact with it. It’s also very rare.”

Giant hogweed, part of the same family as wild parsnip and also part of the city’s campaign, can grow as high as 5.5 metres. Its sap can cause severe inflammation of the skin, purplish scars and temporary or permanent blindness. Hazardous materials gear and professional exterminators are often required to remove it.

Wild parsnip, a botanist argues, is far more benign. Deborah Metsger, assistant curator at the Royal Ontario Museum, is also puzzled by the recent interest in and concern about wild parsnip.

“Honestly, poison ivy is a larger threat to the public than this is. The chance of people coming into contact with wild parsnip is much less than the chance of coming into contact with poison ivy.”

“If someone were to get sap on their skin and then go and wash right away, they’re likely not going to have a reaction,” she adds.

What really concerns Brunton, though, is the way Ottawa is handling the issue. He’s not sure that spraying herbicides over hundreds of kilometres of land to combat a plant very few come into contact with, or get a reaction from, is a wise idea.

“The Ontario College of Family Physicians did an exhaustive literature review of the effects of spraying of herbicides and pesticides associated with weed clearance in residential areas. They came up with the estimate that in areas that stopped using these herbicides, after 10 years, there was a statistically significant drop in the number of cases of cancer. Particularly in regards to children,” he explains.

“It seems to me, the people who are making the decision to use spraying in a residential neighbourhood — I don’t care what they’re using — have a huge professional, legal and moral obligation to address these questions. If one kid in suburban Ottawa in the next five years gets cancer because someone reported they might have gotten a poison ivy-type rash from this thing, that’s too much.”

When contacted, a City of Ottawa representative would only provide general information about wild parsnip, but no specifics on the eradication strategy other than that the spraying was conducted by a licensed contractor. A document titled 2015 Wild Parsnip Strategy outlines the locations targeted by the city for aggressive mowing and spraying.