If you wish to restrict your consumption of hazardous pesticides you are advised to:-

i) eat vegetables and fruit crops (in fact all crops) that have been treated with synthetic pesticides,
ii) to cut down on eating organic vegetables and fruit and
iii) reject the skins of fruit and vegetables.

This advice is the inevitable conclusion from the evidence that has been building up over the last 20 years on the quantities and properties of natural pesticides in plants.

All plants contain a formidable array of natural pesticides which protect them from pests and diseases. When a plant is attacked they produce more of their particular set of natural pesticides .

The concentrations of natural pesticides are much higher than those of synthetic pesticides which results in our daily consumption of natural pesticides being about 1,500 mg compared with 0.1 mg of synthetic pesticides.

Natural pesticides are just as hazardous as synthetic pesticides in that they have been found to be carcinogens, mutagens etc in rodent tests. As is the case with all chemicals, whether man-made or natural, 55% of natural pesticides are known to be hazardous when assessed by rodent toxicological tests.

It is therefore far more important to reduce the amount natural pesticides in the food you eat than that of synthetic pesticides if you want to restrict your intake of hazardous pesticides.

A crop that has not been treated with a synthetic pesticides, as is the case in organic farming is likely to contain more natural pesticides because any attack by a pest or disease will have stimulated the production of more natural pesticides which are normally concentrated in the outer layers of the crop. It is therefore preferable to eat food produced from crops that have been sprayed with synthetic pesticides.

Removing the pesticide-rich skin of a vegetable or fruit will reduce the amount of natural pesticides consumed.

It is estimated that there are thousands of natural pesticides in plants. Toxicological studies have been carried out on 63 of which 55% were found to be hazardous. It would be an enormous task to study them all but much more work is clearly required on the natural pesticides that are judged to be the most hazardous. At the moment it can be said that about 55% of the natural pesticides will be hazardous. All crops contain hazardous natural pesticides and therefore all crops are potentially hazardous.

But we do not carry out risk assessments before eating a particular vegetable or fruit.

We live in ignorance regarding the natural pesticides in our food.

In contrast we know a huge amount about synthetic pesticides and in the UK a risk assessment is carried out before a pesticide can be registered and used to make sure that there is likely to be no harm from the lifetime daily consumption of crops containing residues of synthetic pesticides. The allowable acute one-day intake limit is set at one hundredth of the level at which the acute (high dose) no observed-adverse effect (NOAEL) had been found. Similarly an allowable limit for lifetime exposure – the allowable daily intake- is one hundredth of the chronic or lifetime NOAEL.

There is constant monitoring of the concentrations of synthetic pesticides by the Pesticides Residue Committee in the UK who examine the results of analysis of over 200,000 synthetic pesticide/commodity combinations in thousands of samples each year. The results are reported quarterly. Over the last 8 years it has been found that 50 -70% of all samples contained no residues, that less than 1% contained more than the maximum permissible level and that in such cases it was judged there was no risk to human health. It is worth noting that the few offending samples were of imported products. The concentration of synthetic pesticide residues in food seldom exceeds 1 mg/kg whereas the concentrations of natural pesticides are known to range from 7 to over 10,000 mg/kg.

In the light of the situation highlighted here it would seem that our current procedures for evaluating the potential effect of chemicals is defective and very probably misleading. It also allows pressure groups to misuse the data to frighten the public and influence politicians.

As a first step in reconsidering how we assess the health and environmental impact of all chemicals it would appear sensible to carry out the full range of toxicological tests on some of the hazardous natural pesticides found in a regularly consumed vegetable such as potato and then carry out risk assessments. A comparison of the chronic no-observed-adverse effect levels (and one hundredth of these levels) with the amounts consumed by humans should be a revealing first step.

The EU are currently proposing to ban many synthetic pesticides on the basis of hazard and not on the basis of a risk assessment as used in the UK.

The very least that can be said about this approach is that it is illogical for if the EU were to use the same basis for the hazardous and far more plentiful natural pesticides they would have to ban the consumption of all food crops.

The EU proposals should be opposed on the basis of science, food security and logic.

Everything should be done to advise the EU Commission and Parliament about natural pesticides in food before irrevocable decisions are made.

A 15 question and answer document entitled “Natural and Synthetic Pesticides” is available on request.

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