Bioaccumulation
Before we get into this chapter of Silent Spring, we should be clear about why organic insecticides are so sinister - They can bioaccumulate in our body.
1) When you accidentally take in those chemical (swallowed / absorbed through skin / inhaled) no matter how small the amount is, they will be stored up in your body fat because they are fat-soluble.
2)The chemical will be piled up in your body fat little by little until it reaches a concentration which can make you ill or even dead. So there is no 'safe' amount that you can consume.
3) The chemical can be transferred down the food chains. When a cow eats hay contaminated with organic pesticides, the chemicals will be stored in their fat and also milk. Then the milk is made into butter which will contain much higher amount of chemical.
4) It is proven that organic pesticide can be transferred to infant through milk and placenta, exposing the threat to children who are more susceptible to poisoning.
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| Various products of pesticides. (Image taken from Environmental Health Matters Blog) |
Chapter 3: The Elixirs of Death
INORGANIC PESTICIDE
Arsenic
- found naturally in ores of various metals, small amount in volcanoes, sea water and spring water
- found in English chimney soot
- tasteless, been used in homicide for a long history
- carcinogenic (cancer-causing)
- used as herbicides in 1951 (usually in sodium arsenate form) due to shortage of sulphuric acid to burn off potato vines
- The usage of arsenic at cotton plantation of southern United States nearly wiped out bee-keeping industry
- many livestock and wild animals die, water became unfit to be consumed
- in 1959,one of the major English chemical companies stopped the production of arsenical sprays after the death of a farmer's wife who drank contaminated water
- in 1961, Australia government announced a ban on arsenical herbicides but there was no restriction in United States
- many livestock and wild animals die, water became unfit to be consumed
- in 1959,one of the major English chemical companies stopped the production of arsenical sprays after the death of a farmer's wife who drank contaminated water
- in 1961, Australia government announced a ban on arsenical herbicides but there was no restriction in United States
ORGANIC PESTICIDES - chlorinated hydrocarbons
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| Examples of chlorinated hydrocarbon pesticides. (Image taken from NC State University website) |
Dichloro-diphenyl-trichloro-ethane (DDT)
- created by German chemist in 1874, used as pesticide in 1939 by Paul Müller from Switzerland (Nobel Prize winner) to fight insect-borne diseases and crop destroyers
- harmless in powder form, used to combat lice during wars
- 3 ppm can inhibit essential enzyme in heart muscle
- 5 ppm can cause death in liver cells
- individuals with no known exposure can have 5.3 to 7.4 ppm in body
- agricultural workers can have up to 17.1 ppm
- workers in pesticide industry can have up to 648 ppm
Chlordane
- a diet of 2.5 ppm can be accumulated up to 75 ppm in fat
- 25% industrial solution spilled on skin caused poisoning symptoms in 40 minutes and death
Heptachlor
- constituents of chlordane
- converted into heptachlor epoxide in soil and living organisms
- 4 times as toxic as chlordane
Chlorinated naphthalenes
- causes hepatitis
- causes fatal disease in cattle
- threatening workers in electrical industry and agriculture
Dieldrin
- 5 times as toxic as DDT when swallowed, 40 times as toxic when absorbed through skin
- affect nervous system, causing convulsion
- causes severe damage to liver
Aldrin
- will be converted into dieldrin
- causes degenerative change to liver and kidney
- causes sterility
- a size of aspirin tablet can kill 400 quail
Endrin
- 5 times as toxic as dieldrin
- a baby contacted endrin residue lost sight and hearing and had muscular spasms
ORGANIC PESTICIDES - alkyl / organic phosphates (organic esters of phosphoric acid)
Parathion
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| Structure of some organic phosphate pesticides. (Image taken from Openi website) |
- discovered by German chemist, Gerhard Schrader in late 1930's as weapons in wars
- acute (immediate) poisoning when in contact
- destroy enzymes essential in nervous system functioning (resembles alkaloid poison muscarine found in fly amanita, a type of poisonous mushroom)
[Acetylcholine is an enzyme that transmits nerve impulse and will be destroyed as soon as impulse is sent. Cholinesterase is another enzyme which is responsible in disintegrate acetylcholine. Parathion destroys cholinesterase, causing accumulation of acetylcholine]
- causes uncoordinated movements (tremors, muscular spasms, convulsions)
- decomposes quickly (but long enough to be a threat)
- in Florida, two children had contact with an empty bag contaminated with parathion died while three of their playmates got ill
- in Wisconsin, one child who ran into the barn when the spraying was carried out and touched the nozzle died, same thing happened to another child who was playing at the adjoining field
- honey bees showed aggressive behaviors and performed frantic cleaning movement, died in half an hour
- a chemist with antidotes at hand swallowed 0.00424 ounce and got paralysis instantaneously
- used for suicide in Finland
- in California, there were more than 200 cases of accidental parathion poisoning per year
- in 1958, there were 100 cases in India and 67 cases in Syria
- in Japan, there were 336 cases per year
- in Riverside, California, 11 out of 30 orange pickers suffered retching, half-blind and semi-conscious for 16 to 19 days although the orchard was sprayed two and a half weeks ago
- even though parathion was applied 6 months ago with standard dosage, it was still found in orange peel
Malathion
- almost as familiar to public as DDT
- considered as the least toxic of this group of chemical
- it is safe due to detoxification in mammalian liver
- when combined with certain other organic phosphates (need not to be insecticide), poisoning effect will be up to 50 times than predicted
[The process is called potentiation as one compound destroys the detoxifying enzymes in liver, so the person will be vulnerable towards malathion. The two compounds do not have to be given at the same time to have that effect]
- parathion and malathion are proven to magnify the toxicity of some drugs used as muscle relaxants and increase the sleeping time of barbiturates
- being used on nearly a million acres of Florida communities for the Mediterranean fruit fly
SYSTEMATIC INSECTICIDES
HERBICIDES - both organic or inorganic
- spread through all the tissues of a plant or animal to make them toxic to pest
- found naturally or synthetically produced, most drawn from organophosphorus groups because the residue problem is less acute
- applied to seeds by soaking or coating combined with carbon
- the following plant generation produced might be poisonous as well
- in animals, the amount of chemical used must be in balance so that it could create an insecticidal effect in blood and tissues without causing poisoning
- wheat growing in soil containing sodium selenate is immune from aphids or spider mites attack (the first systemic pesticide)
- in San Joaquin Valley, California, in 1959, 25 farm laborers suddenly fell ill after handling the bags of treated cotton seeds
- poisonous nectar was produced in areas treated with schradan before the flowers were formed
- used to control cattle grub (parasites to livestock)
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| Spraying of herbicides. (Image taken from yardcare.com) |
HERBICIDES - both organic or inorganic
Arsenic [as stated above]
Dinitrophenol
- strong metabolic stimulant
- once used as reducing drug but several patients died or suffered permanent injury, so its use as drug was stopped
Pentachlorophenol
- used as weed killer and insecticide along rail road tracks and waste areas
- fatally interfere with the body's source of energy
- a tank truck driver contacted the chemical with bare hand while preparing a cotton defoliant became acutely ill and died the next day although he washed his hands
Aminotriazole / Amitrol
- having relatively low toxicity
- can cause malignant tumors of thyroid for long exposure
