The following information is pasted from a website called ‘The Poison Garden’:
People who grow parsnips often leave them in the ground and harvest them as required. This may mean that, in the spring, unharvested plants run to seed and are of no use. A visitor to this site reported two occasions when after clearing his allotment of some mature plants on a sunny day, he suffered blistering to his arms and a change in pigmentation which lasted six months. The first year he did not realise what has caused the burns but when it happened a second time he realised that he had been handling the mature Pastinaca sativa previously.
Two children were helping their father remove some run to seed parsnips from the allotment. 48 hours later they came up in blisters described as ‘the size of marbles’. It is to be hoped their experience doesn’t put them off gardening completely.
Incidents in the literature seem to refer to wild parsnips more often that the cultivated varieties. Some work has suggested that fungal infection of the root results in a significant increase in the furocoumarin content. The work was done using harvested parsnips stored under different conditions but it may explain why the problem occurs only with older plants.
It may be, however, that bright sunlight is required to cause the burning to occur and thus parsnips harvested through the winter do not give rise to problems.
In August 2010, the UK’s Daily Mail reported the case of a woman who removed her shirt on a hot, sunny day whilst working with her parsnips and, having brushed the leaves across her stomach, as she worked, found, two days later that her skin suffered burns and blisters. She was advised to attend hospital.
The woman concerned, Mrs Jo Miles, has been kind enough to give permission for some pictures of the burns she suffered to appear here.
Mrs Miles is willing for these pictures to be used because she wants as many people as possible to realise the potential for harm arising from exposing the skin to this plant on a sunny day.
The fact that, it seems, not all parsnip plants produce these effects makes the danger greater because people who have suffered no harm for years may find themselves exposed to a crop which is high in the fourocoumarins that produce the sensitisation of the skin.
Folklore and facts
Pastinaca sativa (parsnip) is an interesting example of the fact that vegetables which people eat without any concern can be harmful in the wrong circumstances. The potential for Solanum tuberosum, potato, to become toxic if exposed to the sun is well-known, as is the poisonous nature of Lycopersicon esculentum, tomato plant foliage and the need to cook Solanum melongena, aubergine, to destroy the toxins.
It seems odd that Pastinaca sativa are not included in the Horticultural Trades Association classification of potentially harmful plants. Parsnip, which can result in moderate burning, is unclassified and, by implication, harmless. This, on the face of it, looks like an example of the horticultural industry’s fear that buyers could be deterred by being given information about a plant’s ability to cause problems.
In some Celtic cultures, all fires were extinguished on 31st October before being relit from a flame source provided by a priest. The fire was transferred from the priest to the various fires in the home by carrying lighted coals in a hollowed out parsnip or carrot. It is believed that this is the source of the American tradition of hollowing out a pumpkin and placing a lantern in it. The pumpkin was not known in Europe and it is thought that settlers in America found that it provided a better vessel for distributing the Halloween flame than the parsnip.