Silvia Zechmann
On various forums for gardening or household tips on the Internet are "recipes" on how to make a supposedly natural, ecological and yet very effective remedy for pests from tobacco. Even some gardeners advise their customers to use a tobacco extract as insecticide. In fact, we occasionally find noticeable residues of nicotine in fruit and vegetable samples, also from Germany. Nicotine is very toxic and we strongly advise against the use of tobacco as a "biological" or even "harmless pesticide"!
Illustration 1: Tobacco (Photo: Jan Mesaros/Pixabay, CC0 Public Domain).
Since we screen our samples of plant origin for nicotine residues, we occasionally find residues of nicotine in fruit and vegetable products, also in products from Germany.
Nicotine is a neurotoxin that is harmful to humans and, to a greater extent, to insects. It is naturally produced in plants of the nightshade family, but apart from tobacco, the contents are low. Nicotine is one of the most toxic pesticides that were ever approved in Europe. While nicotine is still partly used in third countries (as a pesticide or as a tobacco preparation), it is no longer authorized as a pesticide active substance in plant protection products in the EU since 2010, due to its high toxicity [1].
All the more surprising for us were the many finds of "recipes" in various forums for gardening or household tips on the Internet. These describe how to use tobacco as a natural product to produce supposedly natural, biological and yet very effective remedies against insects. Generally, the tobacco should not be spread on the plants directly. Instead, it is recommended to make a decoction from, for example, one liter of water and some crumbled cigarettes, which should then steep for several days before being sprayed onto the plants.
Partly warnings are issued in the forums to use the decoction only outdoors, in the absence of children and / or only for ornamental plants. However, in many cases the high toxicity of nicotine in the tobacco is not mentioned in any way. Investigations showed that individual gardeners even advise their customers to use tobacco decoction as a natural, insect repellent, even for food-producing plants.
Illustration 2: Tobacco plantation (Photo: Bishnu Sarangi/Pixabay, CC0 Public Domain).
In fact, in the samples we analyze, we occasionally find noticeable residues of nicotine, also in fruit and vegetable samples from the EU and Germany. Those are residue findings above the levels that would be expected from natural levels of the plants themselves, from contamination with tobacco dusts or smoker's hands. The legal limit for nicotine in most products of plant origin is 0.01 mg/kg. Only for a few products the legal limit is set to higher values, for example for tea, mushrooms, spices or herbs [2].
At CVUA Stuttgart, 229 samples of foods from plant origin, with a maximum level set to 0.01 mg/kg, were analyzed for nicotine in the past 18 months (see the table below).
From 94 German samples analyzed for nicotine, four showed abnormal high nicotine findings above the maximum level set in Regulation (EC) No 396/2005. For two of these four samples, the maximum levels were exceeded even after taking into account the measurement uncertainty of 50 %. These samples were reported to the authorities: an oak leaf lettuce and a currants sample.
| Country of origin |
Number of samples*
|
Number of samples containing the following nicotine residues
|
||
|---|---|---|---|---|
|
≤ 0.01 mg/kg**
|
> 0.01 mg/kg und ≤ 0.02 mg/kg
|
> 0.02 mg/kg***
|
||
| All samples |
229
|
208
|
7
|
14
|
| Germany |
94
|
90
|
2
|
2
|
| EU (without Germany) |
11
|
9
|
0
|
2
|
| Third countries |
124
|
109
|
5
|
10
|
How such high nicotine residues in German samples and in samples from the EU can occur, although nicotine is no longer approved as a pesticide active ingredient, is not yet conclusively clarified. Our investigations will be continued and the topic “nicotine” will be observed further.
In any case, nicotine is poisonous and we strongly discourage the use of tobacco as a "biological" or even "harmless" remedy against insects!
Nicotine is a neurotoxin and binds in the brain to the so-called acetylcholine receptors, which are specialized binding sites on the cells for certain biochemical signaling processes. Among other things, the substance causes an increase in the respiratory rate, the blood pressure, the heart rate and also promotes the blood coagulation tendency, which increases the risk of thrombosis [3,4].
In order to estimate possible acute toxic risks associated with short-term exposure, the amount of residues taken in the consumption of a food is compared with the so-called acute reference dose (ARfD). The ARfD for nicotine is 0.0008 mg/kg of body weight [4,5].
[1] 2009/9/EC: Commission Decision of 8 December 2008 concerning the non-inclusion of nicotine in Annex I to Council Directive 91/414/EEC and the withdrawal of authorisations for plant protection products containing that substance
[2] Regulation (EC) No 396/2005 of the European Parliament and of the Council of 23 February 2005 on maximum residue levels of pesticides in or on food and feed of plant and animal origin and amending Council Directive 91/414/EECText with EEA relevance.
[3] https://www.dkfz.de/de/rauchertelefon/Nikotin_Wirkung.html (viewed on 01.09.2017)
[4] EFSA Statement: Potential risks for public health due to the presence of nicotine in wild mushrooms. The EFSA Journal (2009) RN-286, 1–47
[5] Stellungnahme 009/2009 des BfR vom 28. Februar 2009: Nikotin in getrockneten Steinpilzen: Ursache der Belastung muss geklärt werden
Chemisches und Veterinäruntersuchungsamt Stuttgart
Postfach 1206 · 70702 Fellbach
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