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Yes. Where there are many plants that are classified as poisonous, this document will discuss 4 common plants found in Canada. While this document covers these 4 plants specifically, the prevention and treatment steps may apply when working with other plants. For a full list of poisonous plants in Canada, see the Canadian Poisonous Plants Information System.
Poisonous plants that commonly cause allergic reactions include poison ivy, poison oak, and poison sumac. Giant hogweed can cause severe burns and possibly blindness.
Poison ivy is found across Canada, while poison oak is found on the western Canada (British Columbia) and poison sumac is found in central and eastern Canada. Giant hogweed is a recent invasive species and has been found in many provinces across Canada.
Workers at risk include farmers, foresters, landscapers, groundskeepers, gardeners, construction and road workers, labourers, and any other workers such as camp or recreational workers who spend time outside near vegetation. Also at risk are forestry workers and firefighters who may fight forest fires as there is an increased risk of injury from inhalation exposure when the plants burn.
Poison ivy: Poison ivy is typically a vine or shrub with three leaves close together. The leaves are green and turn red in fall. There are small yellow or green flowers which later turn into small berries that are white, green or yellow.
Image 1 (above): Poison ivy (Image from NIOSH/US Dept. of Agriculture)
Poison oak: Poison oak is typically a shrub with three leaves close together. Pacific poison oak can be vine-like. There are small yellow or green flowers and later these turn into green-yellow or white berries.
Image 2 (above): Poison oak (Image from NIOSH/US Dept. of Agriculture)
Poison sumac: Poison sumac is a woody shrub that has leaves with stems containing 7 to13 leaves. The leaves are arranged mostly in pairs. Berries may be glossy and pale yellow to cream coloured.
Image 3 (above): Poison sumac (Image from NIOSH/US Dept. of Agriculture)
Giant hogweed (giant cow parsnip): Giant hogweed is a very large perennial plant. It has large leaves up to a metre across, and stalks that can reach 6 metres tall in height. As a young plant it may be mistaken for less hazardous wild parsnip. It has white-yellow flowers that are usually in a large cluster up to a metre across.
Image 4 (above): Giant hogweed (Image from WorkSafeBC)
The leaves or other parts of these plants contain an oil that, when it touches your skin or eyes, will usually cause an reaction that can range from irritation (mild itchiness and redness) to an allergic reaction. This reaction is called allergic contact dermatitis. Most exposed people will have an itchy red rash with blisters. Some may experience respiratory symptoms (e.g., difficulty breathing) and fevers. In some cases, a reaction may not occur with the first exposure, but the person may become sensitized and will react to further exposures.
Typical signs and symptoms include:
Indirect contact may occur, such as when bare skin touches gloves or clothes that have been in contact with the plants. Care must be taken when removing gloves or clothing. Also, do not touch your face or skin while working.
If these plants are being burned, inhalation of the burning oil in the plant can cause lung irritation and difficulty breathing.
If you believe you have been in contact, immediately wash the affected area with dishwashing or other degreasing soap and lots of water. Be sure to scrub under nails with a scrub brush and soapy cool water. If soap is not available, vinegar (2 tablespoons in 1 cup of water) or alcohol (1/2 cup to 1/2 cup of water) can be used.
If symptoms appear:
(Note: Only use medications with the advice of a doctor or medical professional.)
Contact with the sap of giant hogweed in the stalk, stems, or leaves can cause serious burns or blindness. The reaction is due to light sensitive chemicals in the sap. The reaction can occur in less than 15 minutes, but it may take many hours for the symptoms to appear. Concerns include:
If you believe you have been exposed to giant hogweed, contact a doctor or medical professional immediately. Also:
Note that affected areas will need to be protected from sunlight using sunglasses or UV protective creams (e.g., sun block cream) for months and possibly for years.
Educate and train workers to know:
Prevent exposure by:
Do not burn poisonous plants. Inhaling the smoke can lead to severe respiratory problems. If burning the plants is necessary, the National Institute for Occupational Safety and Health (NIOSH) recommends the following:
If workers need to use a respirator, then a respiratory protection program is necessary. The program should include the following procedures for:
In addition, CSA standard Z94.4 requires that the employer ensure the individual is medically approved to wear a respirator.
Other OSH Answers documents Designing an Effective PPE Program, Respirator Selection and Respirator Care have additional informational information that will assist in setting up a respiratory protection program.
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Although every effort is made to ensure the accuracy, currency and completeness of the information, CCOHS does not guarantee, warrant, represent or undertake that the information provided is correct, accurate or current. CCOHS is not liable for any loss, claim, or demand arising directly or indirectly from any use or reliance upon the information.