Giant hogweed

There are several causes for concern arising from the presence of Giant hogweed. As well as out-competing and shading out many native species, the plant can play host to the disease Sclerotinia sclerotiorum and the carrot fly - both of which can cause considerable damage to a number of arable and horticultural crops. Along watercourses, Giant hogweed can leave river and stream banks susceptible to erosion during the winter after the plant has died back. Probably the greatest cause for concern, though, is the health hazard Giant hogweed presents to humans.

Health risks to humans

Contact with Giant hogweed sap makes skin highly sensitive to ultra-violet light. There is no inflammation, irritation or any other such discomfort experienced at the moment of contact so it is possible for a person to be completely unaware of their exposure until it is far too late. Around 15-20 hours after exposure burns become apparent, quickly developing into large, watery blisters. Once the blisters have receded they can leave unsightly scars and the affected areas can remain highly photosensitive for years or even for life.

Blindness (temporary or, in some cases, permanent) can occur if sap comes into contact with the eyes. There have also been suggestions that toxins in the sap are carcinogenic and that they could result in malformations of the unborn foetus in pregnant women or could even lead to cancer.

Sap is present in the plant, not only inside the stems, but also on the hairs that cover the outside of the leaves and stems. Therefore any contact at all with any part of the plant can result in long-term damage. Because the person affected can be unaware of having been contaminated with Giant hogweed sap, they are likely to remain in the open air, exposing themselves to further UV radiation and increasing the severity of their burns. For this reason, the health risks are multiplied on sunny days.

Children are particularly susceptible to Giant hogweed burns, since the sheer size of the plant makes it very attractive to them to play in/with. The long, thick, straight, hollow stems are often used as swords, telescopes and blowpipes - with inevitable results. Giant hogweed growing on public access land must surely be a lawsuit waiting to happen and local authorities need to take action.

Treatment following contact

Wash immediately with soap and water any area of skin that comes into contact with Giant hogweed sap. If sap comes into contact with the eyes flush immediately with water. Cover affected areas and keep them out of sunlight for at least 48 hours. Seek medical advice.