Giant Hogweed

You may have heard about the dangers of Giant Hogweed – a non-native invasive plant with can cause burns. So, we have put together the facts for you, from identification to staying safe.

This is something that we all need to be aware of when visiting sites

Where does Giant Hogweed Grow?

Giant Hogweed can be found in bogs, fens, grasslands, woodland, urban, agricultural areas, horticultural areas and most commonly on banks adjacent to rivers, streams & other watercourses.

What does Giant Hogweed Look like?

Giant Hogweed looks like enormous cow parsley. Identifying features include;

o Height

▪ Its’ ‘giant’ stature makes it readily identifiable – it can grow up to 5-6m in height

o Stem

▪ Main stem is large, usually green with purple blotches, hollow and can have stiff white hairy bristles and be 5-10cm in diameter.

o Flowers

▪ White or rarely pink, flowering from June to August. Each plant can have up to 50,000 seeds! They are clustered on umbrella-like heads known as umbels that can reach a diameter of 60cm. All the flowers on the umbel face upwards.

o Leaves

▪ Serrated and sharply divided leaves, which can grow to 3m in length and 1.5m wide. It looks a bit like a rhubarb leaf – which has given rise to one of its other common names – wild rhubarb. The underside of the leaf is hairy.

o Seeds

▪ Dry, flattened, and oval. Almost 1cm long, tan with brown lines extending ¾ of the seed length.

Is Giant Hogweed dangerous?

Giant Hogweed has the potential to pose a threat to human health due to production of a hazardous sap that can cause severe burns and scarring by sensitising the skin to light (UV radiation). The sap contains furocoumarin, which makes skin extremely sensitive to sunlight (phytophotodermatitis). If the sap gets onto your skin, then you are exposed to sun, your skin can blister badly and blistering can recur over months and even years. This is known as phytotoxicity.

What happens if you touch Giant Hogweed?

If you do get giant hogweed sap on your skin, be sure to wash the area thoroughly immediately, seek medical advice and do not expose the area to sunlight for a few days.

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SUMMARY

– Plan your site visits – Use desktop tools such as Google Maps and Google Earth to review the site prior to visiting and assess any risks of the presence of Giant Hogweed.

– Know what to look out for and how to spot it (If in doubt, ask)

– Avoid any contact with Giant Hogweed if you encounter it on your site visits.

– Advise the client/contractor of any existence of Giant Hogweed on the site.

While the hazards may always be present, there are ways and means to prevent harm arising to the personnel involved as outlined above.

Laura McNeill

Senior Health & Safety Consultant