Many consumers are wary of pesticide residues in food and the adverse effects they could be having on their health. Given that these chemicals are added to food because of their ability to kill, it is perhaps unsurprising that consumers have these concerns and that the desire to avoid pesticide residues is one the reasons that some are prepared to pay more for organic produce. However, there is no evidence to suggest that pesticide residues in food are doing any harm to consumers.
The important thing to understand about pesticides (and all potentially toxic compounds) is that their effects are dose dependant. If you take a large dose of a pesticide and feed it to a rat, you may find that the rat develops cancer. This doesn't just apply to pesticides. Many naturally occurring plant compounds have also been found to cause cancer at high doses - about the same proportion of them as pesticides. These plant-produced compounds are a lot more abundant in our food than pesticide residues. It has been calculated that one cup of coffee contains more naturally occurring carcinogens (cancer causing chemicals) than most people consume as pesticide residues in one year. Plants naturally produce their own pesticides and these are in fruit and vegetables at concentrations hundreds of thousands of times higher than the concentrations of the pesticides added by farmers. The reason fruit and vegetables aren't killing us all is that the amounts of these compounds is too low to be harmful and the amount of our pesticides are even lower still.
The toxicity of all pesticides is very thoroughly examined before they are licensed for use. A wide range of tests are performed (including testing on animals) to find a concentration low enough that the pesticide produces no harm. The maximum amount of pesticide residue that is legally allowed in the food is then set at a concentration much lower than this (usually about 1000 times lower) in order to be on the safe side.
This doesn't mean, however, that we shouldn't reduce pesticide usage. While the amounts found on food are far too low to be harmful, the amounts handled by farmers when applying pesticides are much higher and there are cases of farmers being poisoned by pesticides.
One way to reduce pesticide spraying is simply to stop spraying pesticides - the approach taken by organic farmers. The problem with this, however, is that with nothing stopping the pests the yield of the crop decreases. This means that more land has to be used to grow the same amount of food. This in turn drives up the cost of the food produced and is harmful to the environment, since more land needs to be used for agriculture. Most farmers in the developing world simply could not afford to do this.
Another option is to use genetically modified (GM) crops. There are a group of GM crops called 'Bt crops' which have been modified to produce proteins called CRY proteins. These proteins come from a bacterium called 'Bacillus Thuringiensis' and they kill insects. Each CRY protein is very specific to a certain insect, so a plant can be modified to produce CRY proteins that kill its pests without harming other insects. CRY proteins have no effect on humans - they are broken down in our digestive system in the same way as most protein that we eat.
There are multiple benefits of this 'Bt' technology. Firstly, the farmer saves money on pesticides. Secondly the yield is higher. Part of the reason bt crops are more successful than conventional crops sprayed with pesticides is that the CRY proteins are produced inside the plants, where sprayed pesticides will not reach. Also, the CRY proteins are not washed away by rain. In India, rural farmers choose to buy bt cotton seeds, rather than cheaper, conventional cotton seeds, because they more than make the cost back in the savings on pesticide and the increased yield. Finally, using bt crops means that farmers are less at risk of poisoning, because they are spraying less pesticides. A survey of cotton farmers in Northern China between 1999 and 2001 showed that the introduction of bt cotton had reduced the incidence of poisonings.
In summary, we should seek to reduce the spraying of pesticides, because it is harmful and costly to farmers . However, we do not need to worry about pesticide residues on our food, because they are present at amounts far too low to harm us. One method that has been used to reduce pesticide spraying is the deployment of bt crops.
***Click here to see a video about bt cotton in India (you will have to select the video from the panel on the right)***
No comments:
Post a Comment