But earlier this year these spores were found to cause serious, often fatal, lung infections in mice, and to infect wounds and damage human cells in culture. Some people suggest that this technique should be curtailed until further investigations are carried out. What is not known is how much of the lead is transferred to the food we eat.Similarly, organic farmers are allowed to spray crops with bacterial spores to act as a general-purpose insecticide. In Aberdeen, home-made organic goats' cheese initiated an E coli outbreak among children; in Germany an outbreak of Citrobacter that killed one child and damaged nine others was traced to organic parsley treated with pig manure.Organic farmers use sulphur as a weak pesticide But sulphur contains lead, a known danger. Two outbreaks of E coli 0157 in the US were traced to organic strawberries and lettuce. If manure is pasteurised, or if you properly cook contaminated food, then the organism is killed.

The problem is to guarantee that this is done.Oversights do occur. Infection in human beings kills, or leaves victims without functioning kidneys.Citrobacter freundii lives in pigs' guts and is also potentially lethal. Organic farmers preferably apply cow or pig manure when this is available. It can be infected with the dangerous bacterium E coli 0157 disease organism that lives happily in the guts of cattle. There has been no noticeable impact on the environment or health of communities, or distrust of organic food, from the incorporation of these foreign genes. More generally, no crop plant can be seriously regarded as completely "natural"; the first act of domestication is to select desirable individuals from the available gene pool and thereby to diminish genetic variability.There are four concerns about whether organic food is safe. These are not natural plants and they don't survive in fields unless continually cultivated.These genetically manipulated plants have been used in agriculture for 50 years, starting with triticale (1 million hectares planted world- wide).

However, consumption by these people of their own completely fresh produce negates direct assessment of the effects of transport and storage on the safety of micro-organisms.Organic farmers can and do use modern crop varieties, since they have disease resistance and good yields. However these varieties (of, for example, wheat, barley, oats, tomatoes, turnips, sugar beet, blackcurrants, potatoes) acquired their genes from different species by difficult laboratory procedures; for example, rice obtained genes from sorghum wheat. Can we claim the same for organic food? No long-term data of comparable present-day organic consumption is available, except with small farming communities such as the Amish in the US. But constant exposure to mycotoxin carcinogens can be expected to have long-term effects, detectable only by continual monitoring. However, there are no current plans to carry out this monitoring.Such data is hard to find. Alongside the introduction of intensive but strictly regulated agriculture during the last 50 years, human longevity in Britain has increased by five to six years, to its probable biological maximum.