By Dr. Elke Frenzel (Supervisor: Kommunale Unfallversicherung Bayern (KUVB) insurers)
It is important to be able to experience nature. We need to be able to allow our children to discover through their own senses how things taste, smell and feel. And there is nothing that children enjoy more than playing outdoors in a natural environment and using the materials that nature provides for them; at the same time, this is an activity that can contribute significantly to their healthy development. But not just busy roads are a danger to our children; nature too is not without risks. Among these is the threat posed by poisonous plants.
Poisonous plants can be met with everywhere. We encounter them daily ‒ in our own garden or next door, in the park, in the wild, even in window boxes. In our own day, however, the ability to recognise poisonous plants has ceased to be a skill that is naturally handed down through the generations. Parents, educators and teachers often themselves had no garden and little experience of the outdoors when growing up and thus do not have the necessary knowledge to pass on. Even so, not everything we used to tell our children was necessarily correct. For example, many parents used to warn their children that "all red berries are poisonous". The next time we spread redcurrant jam on our toast we should ponder the wisdom of that advice. It is thus the case that there is increasing ignorance with regard to the subject of poisonous plants and this is associated with a growing confusion in this area. The result is that, in certain instances, presumed poisonous plants have been dug up or cleared as a precautionary measure although they in fact represent no actual danger to anyone. And yet there are other plants that have been left in place because they appear attractive and ornamental but have a toxic potential that is completely underestimated.
This confusion is further exacerbated by the many publications on the subject of poisonous plants in which the various authors in some cases come to different conclusions with regard to how poisonous particular plants are. It would thus seem that the best approach would be to provide all concerned parties with suitable information so that their awareness of poisonous plants is improved and any unjustified fears are eliminated. It would also be advisable to define objective criteria on the basis of which it will be possible for planners, educators, teachers and parents to decide whether or not a particular plant is suitable.
What is a poisonous plant?
Anyone who wants to find out more about the toxic potential of plants will run into difficulties. It is true that there are now many publications, specialist articles and (supposed) guidebooks on the subject available. But here the reader will frequently come across contradictory statements with regard to how poisonous individual plants are. Added to this, the classification of plants in categories such as 'mildly toxic', 'toxic' or 'slightly toxic' is of little help when it comes to deciding whether an already established planting (of rowan trees, for example) should be removed from a children's playground.
In the case of plants, 'poisonous' is a relative term. Different plants, although of the same species, may contain differing quantities of toxins while a particular toxin can have different effects on individuals, depending on the individual's age, state of health and even their habituation to the substance in question. Children, particularly young children, are far more at risk as their immature physiologies are unable to break down and eliminate toxins to the same extent as the adult body ‒ think of the effects of alcohol and caffeine.
People should also be made aware of the fact that ingestion of larger quantities of plants that contain no known toxic substances can also cause nausea and vomiting.
And the example of the foxglove perfectly demonstrates how relative the term 'poisonous' is. The substance extracted from the foxglove Digitalis purpurea is used to save the lives of patients with cardiac disorders. And yet for others, ingestion can result in death. As Paracelsus is supposed to have said: "Dosis sola facit venenum" (The dose alone makes the poison).
Cases of poisoning in children
Investigations have shown that children are principally attracted to plants that stand out because they have colourful fruits or blooms. The group most at risk of accidental poisoning consists of children in the age range 1 - 4 years. These children are already sufficiently independently mobile and have not yet developed any inhibitions with regard to eating any berries or flowers they come across while playing in the open. It is only when children are some 4 - 5 years old that they are able to distinguish between foodstuffs and other substances and thus do not put in their mouths things that they discover outdoors.
Poisons information centres in Germany receive 80,000 - 100,000 calls every year concerning cases of assumed poisoning incidents involving children. Queries concerning the potential toxicity of plants are usually in third place after cases relating to the ingestion of medications or household chemicals. In many of these instances of presumed ingestion of toxic plants, the child in question exhibited no corresponding clinical symptoms at the time the call was made. Only in some cases were symptoms apparent and in only a small proportion of these were the symptoms evaluated as moderate to severe.
This demonstrates that the vast majority of plant species has a negligible toxic potential only. Moderate to severe cases of poisoning in children have been registered following ingestion of the plant genera Brugmansia (Angel's Trumpet), Laburnum (e.g. Golden Rain), Phaseolus (e.g. green bean) and Thuja ('tree of life').
Lists of poisonous plants
As well as the above-mentioned (but often not exactly) specialist literature, a vast quantity of advice and lists can be found online. Unfortunately, this oversupply of information is not conducive to reducing the confusion of those seeking clarification. Many online sites are simply used as a platform through which the authors can express their own individual opinions and do not thus provide suitable material on which to base an objective, logical decision. But there are a few sources of substantiated and reliable information to be found. Among these are German standard DIN 18034, the list of poisonous plants issued by the German Ministry of the Environment, Nature Conservation and Nuclear Safety (BMU) and information brochure 202-023 "Giftplanzen – beschauen nicht kauen" (Poisonous plants – view but don't chew) available from the DGUV statutory accident insurance organisation. While DIN 18034 ('Playgrounds and open spaces for play') cites just six poisonous plants and prohibits the planting of these in play areas or requires their removal if present, the BMU list contains 49 plant species and the DGUV brochure 48.
The two latter lists also include plants that can cause moderate or severe symptoms of poisoning when only relatively small amounts of plant material are ingested. They warn that it is dangerous to cultivate these plants in locations in which children tend to gather or play.
As a rule, there are no problems in practice when it comes to excluding use of the six plants cited in DIN 18034, namely Euonymus europaea (the spindle tree), Daphne mezereum (February daphne), Ilex aquifolium (common holly), Laburnum anagyroides (common laburnum), Heracleum mantegazzianum (giant hogweed) and Ambrosia artemisiifolia (common ragweed) and no difficulties in this connection arise in association with consultations, inspections and the planning and operation of playgrounds.
This is not the case with the plants listed in the other two publications. As these include plants that are classified as 'slightly toxic' or 'mildly toxic', there are often discussions as to whether an old established robinia tree or the good old privet hedge could not be retained on a playground or in the external grounds of a child day-care centre. Here the individual evaluation of the risk potential in the given situation becomes decisive.
Assessing the risk associated with plants
There are plants, such as the autumn crocus and hemlock, that will cause death if consumed. There are other plants that can be definitely classified as non-toxic and the consumption of which is even considered part of a balanced diet. Disputes do not arise in practice with regard to these two categories. But between these two extremes is a plethora of plants that are considered to be mildly toxic, slightly toxic or toxic. Objective differentiation is required and it is necessary to define certain criteria on the basis of which it is possible for those involved to decide whether or not to use or retain a particular plant.
Toxicity: The appropriate location for plants that are classified as 'very toxic' is obviously not a children's playground. When establishing a new plant bed, it is advisable to use non-toxic plants cited in positive lists. The criteria below need to be first carefully reviewed before plants that are slightly toxic to toxic are used.
The age range of the children: When deciding whether to use slightly or mildly toxic plants on a playground or recreation ground, it is essential to first establish whether the site is designed to be used by children aged 1 - 5 years and/or older children (10 years or more). The younger the children, the greater the risk if slightly toxic to toxic plants are present. If the age group is unknown or cannot be defined (as for example, in the case of public playgrounds), it should always be assumed that younger children will be present.
Accessibility: There are many situations in practice in which toxic plants are found to be growing on a playground but are difficult to access or even inaccessible for children because of the presence of fencing, barriers etc.; in such situations, there can be no objection to the planting or preservation of these.
Attractiveness: Children find conspicuous blooms and even more so colourful berries to be irresistible. Hence, any plants that produce attractive berries need to be subjected to careful review before they are approved. Factors to be considered in this connection are:
Toxicity (e.g. rowan, elder, etc.)
The flavour of the berries (bitter, sour, sweet, etc.)
After consideration of all four of these categories, it is usually possible to come to a clear decision on whether or not a particular (slightly toxic) plant is appropriate. Irrespective of this, it is always advisable when laying out new plantings to use species found on positive lists (non-poisonous, with educational relevance).
It would be helpful if attitudes towards poisonous plants for use on playgrounds, child day care centres, schools etc. could be steered in a more positive direction. And the subject of poisonous plants should represent a significant feature of the nature education curriculum, whereby, of course, safety aspects should not be ignored. After all, what is the point of removing supposed 'poisonous' plants from the areas where our children play if they will encounter them anyway elsewhere in the natural course of events?
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