Report from the Sub-comittee on the environment and health

Environmental exposure to
natural substances
Naturally occurring active
ingredients
Comparison between
naturally occurring and
syn<strong>the</strong>tic active ingredients
humans, who have deliberately selected <strong>the</strong> crops that are acceptable and
edible. Humans also use poisonous plants, such as <strong>the</strong> coffee plant and
<strong>the</strong> tobacco plant. The tobacco plant, in particular, and its special uses
present a considerable risk of cancer in humans. In connection with <strong>the</strong>
introduction of so-called “Novel Food” products, including products
made <strong>from</strong> genetically modified plants, <strong>the</strong> authorities are carrying out a
risk analysis in line with <strong>the</strong> analysis of pesticides with a view to
protecting <strong>the</strong> consumers.
Unlike pesticides, natural toxins are mainly inside <strong>the</strong> plant and only
exhibit <strong>the</strong>ir toxic effect when o<strong>the</strong>r organisms approach <strong>the</strong> plant, touch
it or eat it. Pesticides, on <strong>the</strong> o<strong>the</strong>r hand, are normally spread over large
areas with <strong>the</strong> aim of eliminating pests with at least 90% effect on <strong>the</strong>
whole area. All organisms within <strong>the</strong> area are <strong>the</strong>reby exposed to and hit
by <strong>the</strong> pesticide or later eat parts of plants containing pesticide residues.
A count of authorised plant protection products carried out in 1998
(Environmental Protection Agency1998b) shows that a total of 9
naturally occurring active ingredients have been authorised. Two o<strong>the</strong>rs
are at <strong>the</strong> application stage. As shown in table 7.2, six are extracted <strong>from</strong>
plants, two <strong>from</strong> minerals and two <strong>from</strong> animals. Application has been
made for use of a wide range of microbiological products as insecticides
or fungicides.
Table 7.2
Naturally occurring substances authorised for use as pesticides, or at <strong>the</strong>
application stage, in Denmark. See also table 9.1 concerning
microbiological pesticides.
Name Type Extracted <strong>from</strong>
“soaps” insecticide/herbicide plants
Pyrethrin I & II Insecticide plants
Soya oil Insecticide plants
Rotenon Insecticide plants
Citronella oil Repellant plants
Sulphur Fungicide mineral
Paraffin oil Insecticide mineral
Gelatine Insecticide animals
Dried blood product Repellant animals
Azadirachtin* Insecticide plants
*at <strong>the</strong> application stage
Apart <strong>from</strong> <strong>the</strong> mineral sulphur, <strong>the</strong>se naturally occurring substances are
relatively easily degradable, so <strong>the</strong>ir action time is short. They are
currently used only on small areas of land, where, as in <strong>the</strong> case of
syn<strong>the</strong>tic active ingredients, <strong>the</strong> aim is to knock out more than 90% of
<strong>the</strong> pests. In principle, <strong>the</strong>re is thus no difference between <strong>the</strong>se
substances and syn<strong>the</strong>tic pesticides, and <strong>the</strong> insecticides mentioned can
be expected to have similar sideeffects on non-target organisms to those
described in section 5.1.
The naturally occurring active ingredients shown in table 7.2 are much
less toxic to mammals and degrade considerably faster than syn<strong>the</strong>tic
pesticides. An example is <strong>the</strong> insecticide pyrethrin I and II, which is
extracted <strong>from</strong> <strong>the</strong> chrysan<strong>the</strong>mum flower. Pyrethrin is poisonous to
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