How do you feel about pesticides in your environment and on your food?
Pesticides
A pesticide is an effect chemical used to kill some organism we do not want, for example an insect or a weed. Effect chemicals are synthetic chemicals designed to change the metabolistic processes (such as growth) of a living organism, for example herbicides and fungicides.
Many pesticides are used in agriculture or gardening. As well as eating roots and leaves, pests can make it easier for disease to attack plants by damaging the surface or covering it with faeces. Viruses, bacteria and fungi can attack the plants. Pesticides used include acaricides (spiders and mites), fungicides (fungi), herbicides (weeds), insecticides, molluscicides (slugs and snails), nematicides (nematodes and eelworms) and rodenticides (rats and mice). Different pesticides may be used at different stages of a crop's life cycle.
Farmers will sometimes play 'better safe and sorry', and use more pesticides than are actually needed. Exact tailoring of applications of pesticides may be more expensive than blanket application. The excess may leach out of soils and into the waterways or underground aquifers (porous underground rocks that hold water). These aquifers may be used for drinking water. Not all pesticides found in drinking water come from agriculture; for example the herbicide Atrazine in Europe.
Pesticides have enabled farmers to virtually eliminate weeds, so they can produce more food to sustain our ever-increasing populations. This means, however, that the insects that live on the weeds and the birds that live on the insects suffer. The loss of birds may not concern farmers, but a reduction of bumblebees to pollinate crops may. Farmers can also sow more autumn crops, which reduces the seeds available for the birds. This is the kind of effect made famous by Rachel Carson's book "Silent Spring". One of her main concerns was DDT, which was used against lice during World War 2 and against mosquitoes since then to control malaria.
Pesticides may be diluted with clays, talc and water before being sprayed, dusted or worked into the soil. When sprays are carried out by aircraft, only about 50 percent of the spray reaches its target.
Each pesticide generally targets a single aspect of the intended plant or animal which is often controlled by a single gene. Fungal diseases and insect pests can go through several generations in a season, with mutations occurring naturally and possibly even as a result of the pesticides. A small proportion of the mutants may survive and build up resistance to the pesticide, as the pesticide kills off most of their competition. This means that new generations of pesticides may soon be needed, in a never ending "arms race". This can be reduced by rotation of pesticides.
Another problem with insects surviving a pesticide is that they may be eaten by small birds who accumulate the pesticide in their bodies, and those birds may be eaten by larger birds who concentrate the pesticide further, and so on up the food chain. This process is called bioaccumulation. For example, there are areas where California Condors cannot breed because they pick up too much DDT and it makes their eggshells too thin to take the weight of the sitting bird. DDT can also cause alligators to produce far more females than males, and reduce sperm count in humans. Pesticide residues can end up in human food.
Genetic engineering may be used to produce plants which are unaffected by a particular herbicide (for example "Roundup" which is supplied by Monsanto along with the modified seed) unlike their unmodified equivalents. This allows those herbicides to be sprayed around those plants, eliminating the need to weed. This may reduce the overall number of applications of herbicide required. 60 percent of pesticide application in the USA goes to control the insects that attack cotton, so this is a major target for genetic engineering. GMO crops are also being designed to produce their own pesticides.
Pesticides are also used during transport and storage. For example, methyl bromide is often used as a fumigant on food to be transported.
Where crops are labour-intensive and don't enter the food chain, such as rose-growing in Columbia, then there may be little care about how much harm is caused to the workers and the environment.
Organic farming is carried out using no pesticides. If no pesticides were used and there were more pest damage as a result, we might have to convert more land to agriculture to make up the shortfall. Pesticides may also mean less ploughing under of weeds into the soil, reducing soil erosion, and therefore less leaching of nitrates and phosphates.
It can take a lot of energy to produce some pesticides. It can also be dangerous to produce them (Bhopal, for example). Some pesticides persist in nature after use, and others break down. Some are toxic to animals, and others are not. Some pesticides are Persistent Organic Pollutants (POPs) and subject to being phased out or banned.
EU Commission weighs environment against industry
European Commission President Jose Manuel Barroso took office in November 2004 and called for a broad debate about environmental policy, delaying a planned initiative on air pollution and other "strategies". A meeting on Wednesday will wrestle with problems such as how to cut air pollution without harming industry financially. Issues that need resolution include the marine environment, pesticides, sustainable use of resources, soil quality, urban environmental management and waste prevention and recycling. Environmentalists are concerned about any delay or slowing down of environmental progress because of costs. The EU economy is sluggish, so there is resistance to anything that may harm industry. At the moment the 'REACH' bill to mandate the registration and testing of thousands of chemicals is having a bumpy ride.
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