From a website called "the Poion Garden"
"How Poisonous, How Harmful?
Contains cytisine, a quinolizidine alkaloid whose effects are often described as being very similar to nicotine. It seems, however, that it is not nearly as strong a poison as nicotine.
All parts of the tree are poisonous: roots, bark, wood, leaves, flower-buds, petals, and seedpods. The harmful part of the plant is the seedpods which are mistaken by children for peapods, usually after they have been shown how to eat fresh raw peas straight from the plant in the vegetable garden.
In many cases of ingestion of a small number of seeds there are no symptoms. Where symptoms do occur these are usually nausea and vomiting. Higher doses can produce intense sleepiness, convulsive possibly tetanic movements, coma, slight frothing at the mouth and unequally dilated pupils.
In 'Accidental poisoning deaths in British children 1958-77'* published by the British Medical Journal, Neil C Fraser writes 'Laburnum is frequently cited as the most toxic and commonly fatal poisonous plant in both children and adults, but there appears to be no report this century of a childhood poisoning death'.
In a 1979 contribution to ‘The Lancet’ entitled ‘Have you Eaten Laburnum?’, R M Forrester says that there are around 3,000 hospital admissions due to Laburnum poisoning each year. This figure is arrived at by extrapolating from the number of cases reported in the north-west of England. Yet, there are no reported cases of deaths in children due to laburnum. Forrester says ‘It is suggested that laburnum is not as dangerous as has been thought and that many of these admissions are unnecessary’.
There was a case, in 1970, where a paranoid schizophrenic, resident in a mental hospital, was believed to have committed suicide by eating a very large quantity of the fruits and this may have led to the belief that the tree was extremely dangerous. The case provided quite a puzzle for investigators since the man had had a brief conversation with a nurse only about ten minutes before death and had not reported or manifested any of the gastro-intestinal symptoms normally expected with severe laburnum poisoning.
*The article also says that in the period covered there were three deaths of children under 10 attributed to plants. Even this low number is overstated since one death was due to fungi and in one of the other two 'the role of ingestion in the child's demise is doubtful'. Thus there may have been only one confirmed plant death, with 'hemlock' being the plant responsible, in twenty years. The report deals with a total of 598 deaths and makes it clear that medication, household cleaning materials and cosmetics pose a much higher risk than poison plants."
The article does go on to say elsewhere that breathing dust from sawing, or the fuzz of the leaves can be extrememly irritating to the lungs.
