Fighting the Fear of Pesticides

Many people believe that all pesticides are to be feared. This fear is constantly stoked by single issue NGOs such as the Soil Association and often in the written and broadcast media. For example the Soil Association's website claims "What we do know is that 150 of the available 311 pesticides commonly used have been identified as potentially causing cancer." and "The most dangerous chemicals used in farming, such as organophosphates, have been linked with a range of problems including cancer, decreasing male fertility, foetal abnormalities, chronic fatigue syndrome in children and Parkinson's disease". The basis for such scare stories and the origin of the fears is not to be found in any disaster story about harm caused by a particular pesticide or in epidemiological studies but in the 1962 book "Silent Spring" by Rachel Carson, a marine biologist. Central to her thesis about pesticides was her belief encapsulated in this quotation "For the first time in the history of the world, every human being is subjected to contact with dangerous chemicals from the moment of conception until death." DDT was Carson's main target which she claimed was responsible for deaths of raptors and she forecast that it would cause cancer in humans. The Advisory Committee for Toxic Chemicals in the UK in 1969 concluded "that there was no clear relation between the populations of predatory birds and DDT; the link with eggshell thinning, claimed by Carson, was not confirmed. Carson's attack on DDT led to its reduced use for mosquito and malaria control which it was estimated in 2007 has resulted in the deaths of possibly as many as 20 million children. All our food contains dangerous chemicals - many of which are more dangerous than the pesticides Carson abhorred – and that we eat far more of these natural chemicals than we do of the man-made pesticides. The organic movement still does not appear to appreciate this. Carson did not damn all pesticides, but unfortunately she was seen as doing so. She was forthright in highlighting cancer claiming that pesticides were the cause of 25 % human cancers. Carson was suffering from cancer when writing the "Silent Spring". At about the same time as "Silent Spring" was published Europe (but not America) was experiencing the thalidomide disaster – the deaths and severe birth deformities caused by the use of a drug to reduce symptoms of morning sickness and this heightened the fear of "chemicals" used in agriculture or The increased attention given to the regulation and use of pesticides was probably the most important legacy of Carson, but at the same time pesticides became objects of fear and hatred in the public's mind. The focusing on cancer could be said to have hindered the assessment of risk when interpreting toxicological studies. Although known for many years it is seldom recognised that about 50% of all chemicals, both natural and man-made are carcinogenic in animal tests when sufficient is fed. As Paracelsus said "All things are poison, and nothing is without poison; only the dose permits something not to be poisonous". In fact in order for a pesticide to induce cancer it is often necessary to force feed the test animal. Pesticides and cancer became close bedfellows. We continue to be told about substances that potentially cause cancer so it is inevitable that the media link pesticides with cancer statistics without any consideration that cancer incidence is age related; cancer is a more common disease of the old. Surveys in America have shown that when people are asked about the factors causing health problems they rate the environment as being more relevant than their own personal behaviour. Pollution and pesticides are judged as being more important than diet and smoking. It is now recognised that it is a mistake to assess cancer incidence on the basis of the total numbers of deaths as Carson did. It is necessary to adjust the numbers according to population size, for age and to remove smoking related cancers. When this is done it appears, at least in America, that non-smokers have experienced reduced cancer incidences over the last 50 years. There is no evidence of a cancer epidemic.