Chapter 9

Fatal Farming and Pestilential Problems

IN A PERFECT WORLD a pesticide would kill the pest without harming the host organism, be it plant or animal, and it would, ideally, then be de-activated and so rendered harmless.

But the world isn’t perfect and many pesticides are very toxic to humans, particularly after repeated, long-term exposure to low levels or to a large single dose. Some countries have now banned certain pesticides because of the toxic effects suffered by their agricultural workers, or because of their persistence in the food chain.

Agent Orange and Co.

A defoliant is a special type of herbicide that causes leaves to fall off trees and bushes. When used in warfare it can deny cover to the enemy. Such chemicals were being developed at the end of World War I, but were never used in that conflict. The United States Air Force used defoliants on some jungle areas near Saigon in Vietnam in the 1960s. Agent Orange, the most widely used defoliant in Vietnam, was made up of a mixture of weed killers, known as 2,4D and 2,4,5-T, (2, 4-dichlorophenoxyacetic acid and 2,4,5-trichlorophenoxyacetic acid). These chemicals are synthetic auxins or plant hormones.

Dioxins first came to attention during the Vietnam War, as contaminants of the defoliant Agent Orange. They are highly poisonous materials, produced as by-products in the manufacture of commercial chemical products, including herbicides such as the polychlorinated biphenyls or PCBs, and also by the combustion of plastics. Dioxins were considered responsible for the development of chloracne, a persistent and severe form of acne, and have also been found to be potent teratogens and carcinogens. The most toxic dioxin known is TCDD (2,3,7,8-tetrachlorodibenzo-p-dioxin).

In September 2004, Viktor Yushenko, the Ukrainian opposition leader, was poisoned with this most toxic of the dioxins, but fortunately survived, although before and after photographs in the press showed that he suffered a very bad case of chloracne. Tests found that Yushenko had a blood level of TCDD some 3,000 times higher than normal. It is believed that the poison was administered to the politician during a meal he had at the Kiev Dacha of Igor Smeshko, the head of the Ukrainian secret service. It was claimed that former KGB agents were probably involved in the incident, because of the forthcoming election. When the election was held in November, there was such an outcry at the irregularities found that the election had to be re-run on December 26th when Yushenko was declared the victor.

In December 2008, a food scare involving dioxins found in pork and pork meat products from Ireland made headlines. All such foodstuffs were removed from shops and supermarkets in a number of countries. The pigs on ten farms in the Republic and a further nine in Northern Ireland had been fed on contaminated pig feed. This pig meat had been mixed with that from a further 490 unaffected farms before this came to light. The contaminated feed was produced at a recycling plant where breadcrumbs used in the feed were heated with an ‘inappropriate’ oil and the contamination with dioxins occurred during this process. The Irish Food Board applied a special label to all such products made after December 7th that year to indicate that they were unaffected by this contamination with dioxins.

The agricultural and horticultural industries wish to optimise growth of their crops, be they plants or animals. To achieve this they need to use pesticides to kill off harmful organisms. A few pesticides are of natural origin, but most are now manufactured synthetic substances. As far as possible, the synthetic ones are designed to be effective against a specific pest, while avoiding unwanted toxic effects to other organisms.

The vast majority of pesticides and fungicides work either by direct contact or by a systemic action. However, in recent years biological pest control methods have been developed, and these are of particular use to those using organic growing methods.

Organophosphates

Contact pesticides work directly by hitting the pest, either from a spray, or as the pest crawls over a treated surface. Systemic pesticides are chemicals absorbed into the plant and transported throughout the plant in the sap. This type of pesticide is most useful against sap-sucking pests, like aphids, but far less useful for pests who chew their food, such as caterpillars, beetles and earwigs.

In a bid to improve their effectiveness, some pesticides contain combinations of both the contact and systemic types of chemicals. Thorough spraying of all the plants requiring treatment, especially to the underside of leaves where pests tend to lurk in the shade, is essential with all pesticides.

The organophosphorus compounds, such as malathion, are an important group of pesticides that work by paralysing the nervous system by stopping the enzyme cholinesterase from working, which leads to a build-up of the neurotransmitter acetylcholine, with paralysis and then death. See Appendix IV for a more detailed explanation. Malathion, one of the least toxic, is a pesticide considered safe enough for ordinary garden use, being effective against houseflies, aphids and thrips, but it is only partially able to control red spider mite and scale insects. Indeed, it is so relatively safe that it is even used medicinally to kill the head lice and their eggs that infest so many schoolchildren.

Biological controls

Some greenhouse pests, such as whitefly and red spider mite, have already developed pesticide-resistant strains, so here biological control is a better alternative. The biological pest-control methods that are now being developed mean that pesticide use can be drastically reduced or even replaced altogether, which is of major importance to those who are using organic growth methods.

Natural predators as well as parasitic flies and wasps have been used, but these are often highly species specific. Other biological control methods include spraying the pest with fatal doses of hormones, or releasing quantities of sterile males of a pest species. This then results in a reduction of the breeding rate of the pest females. Another method is to spray plants with a biological pesticide, such as a bacterium or fungus that is toxic to a particular pest species.

There is also the somewhat controversial method of breeding disease-resistant varieties or species of crops by the use of genetic engineering techniques.

DDT and friends

Insecticides are designed specifically to kill a variety of insect pests, such as insects, mites, nematodes and molluscs. The earliest insecticides – derris, nicotine and pyrethrum – were all natural products, extracted from plants. A major advance came with the introduction of organochlorine insecticides such as DDT in the 1950s and 60s. DDT, short for dichlorodiphenyltrichloroethane, is a powerful and very persistent insecticide which was used to control mosquitoes in countries where malaria was a problem. Although not toxic to plants, the persistence of DDT in the food chain resulted in its accumulation in the bodies of higher animals, including humans.

Being fat soluble, toxicity from the organochlorines moved up the food chain with disastrous consequences, killing off many birds and small animals who had eaten insects sprayed with these insecticides, and then been eaten themselves, so accumulating the poison up the food chain. They were widely used for many years until concern about their safety led to restrictions in their use. Eventually a complete ban was imposed on their use in the Western world. However, they are still used in the developing world because they are so cheap, compared with the cost of newer, safer agents that are now used in the Western world.

Chlorinated insecticides such as dieldrin and aldrin had high contact and stomach toxicity to most insects, but this type of pesticide also proved to be very persistent in the environment, also being stored in the bodies of birds and mammals. As a result, they too are now little used, except in the eradication of termites. The chlorinated hydrocarbon insecticides, such as chlordane and lindane, also proved to be toxic to higher animals and so are no longer used.

Nowadays, the most important of the newer insecticides are the organophosphates and carbamates, which are used as liquids in sprays and dips, and also as dusts, granules and pellets. Like the organophosphates, the carbamate insecticides inhibit the enzyme cholinesterase, but they differ in that their action is generally less intense, and more rapidly reversible. They enter the central nervous system less readily than the organophosphates, with the result that severe effects on the brain are less common. These substances vary widely in their persistence, toxicity and selectivity of action.

Unfortunately overuse of some of these pesticides has led to the extinction of a number of species of insects in various parts of the world, while other species have now become resistant to their effects and continue to ravage crops.

Boron and fluoride insecticides

Boric acid was used in the past as an insecticide, for both ants and cockroaches. Borates were and are added to plant fertilisers because boron is vital for plant growth. However, both boric acid and its salts, the borates, are also poisonous to humans. A number of cases of boron poisoning appear elsewhere in this book, including victims who were babies, in Chapter 13.

Sodium fluoride has also been used as an insecticide, with such products once available in the US for ants and also for cockroaches. Unfortunately, they were also exceedingly poisonous to humans too, and so are no longer available. A case involving a child is included in Chapter 13 and two such poisonings are described in Chapter 14.

Safer killers

A safer natural alternative, pyrethrum, is a mixture of pyrethrins and cinerins obtained from chrysanthemum flowers. This powerful but non-persistent contact insecticide has a rapid knock-down effect. It is non-toxic to mammals and so is widely used in the food industry and in the home, usually in combination with piperonyl butoxide, which acts as a synergist, making it even more effective. For houseflies, diazinon is a particularly useful insecticide, and rotenone, the active ingredient in derris, is a non-systemic type of natural insecticide which is widely used in both agriculture and horticulture.

Carbaryl is a carbamate insecticide which was used for many years as a lotion and as a shampoo for the treatment of both head lice and crab lice. It has also been widely used in veterinary practice, horticulture and agriculture. Following reports of tumours in experimental animals, the UK Department of Health advised, in late 1995, that carbaryl should be considered to be a potential human carcinogen. Consequently, its medicinal use for the treatment of head lice and crab lice since then has been restricted to prescription only for human use.

Killing larvae

Larvicides kill the pre-adult form of some pests such as caterpillars. Several organophosphates are used for this purpose, and are of particular use in tropical areas for the treatment of rivers where a number of pests cause illness in humans. Phoxim and pyraclofos are both used in the larvicidal treatment of rivers to control onchocerciasis, better known as river blindness.

Temefos is another organophosphate, and it is effective against the larvae of mosquitoes, blackflies and other insects. It has been used in the control of dracontiasis (guinea worm infection), as it is effective against the crustacean host of the larvae of the guinea worm. Like phoxim and pyraclofos, mentioned above, temefos is also used in the larvicidal treatment of rivers in the control of river blindness.

Diflubenzuron is both an insecticide and larvicide, acting as a growth regulator by interfering with the formation of the cuticle by the larvae, and so inhibiting their development to the adult stage. It is used in agriculture and in the control of vectors, which transmit disease. It also has residual activity against mosquito larvae.

Slugs and snails

Molluscicides such as endon and metaldehyde are both used to kill slugs and snails. These agents are particularly useful to control the snail vector in schistosomiasis, also known as bilharzia, one of the most serious tropical diseases affecting humans. Bilharzia was named after Theodor Bilharz, who in 1851 discovered and identified Schistosoma eggs in the corpses of those who had died of this tropical disease.

Today a single dose of praziquantel is sufficient to treat a person (the human vector) infected by this fluke parasite. Unfortunately, this drug is not effective against either the immature worms or the eggs, so there is a need to use molluscicides as well.

Metaldehyde is used in pellet form, which can be very dangerous to small children and to any animals that may find and eat the pellets. The symptoms of metaldehyde poisoning are somewhat delayed and include vomiting, diarrhoea, fever, drowsiness, convulsions and coma; kidney and liver damage may occur with death from respiratory failure following within 48 hours. Metaldehyde will appear again in a later chapter on household horrors.

Rats, mice and other rodents

Rodents are herbivorous or omnivorous mammals that have become pests all over the world, causing considerable economic and medical problems because they get into stored food and because they carry plague fleas. Rodents include squirrels, beavers, gophers, rats, mice, voles, hamsters, porcupines, guinea pigs and agoutis. The control of rodents is of vital importance to public health, and rodenticides are an essential control method, as the use of traps alone cannot control numbers sufficiently.

Aluminium and zinc phosphides are used as rodenticides in the form of pastes, as well as to fumigate grain. In the presence of moisture these pastes release a poisonous gas called phosphine, which accounts for the pesticidal activity. Phosphine has a garlic-like odour, which is repulsive to people and also to domestic animals, but apparently not to rats. However, it is exceedingly poisonous to poultry, and so this type of rodenticide should never be used anywhere near chicken runs or sheds. It is also poisonous to humans and needs to be used with caution.

A few years ago, members of the ambulance, medical and nursing staff as well as parts of Arrowe Park Hospital, near Birkenhead on Merseyside, needed decontaminating because of phosphine gas. The gas was emanating from a dead body, which had been sent to the hospital. Having terminal cancer, the man had used a phosphide rat killer as a method of committing suicide.

In 2005, a horse sanctuary near Norwich, which had been careless and allowed some of its workers to inhale the fumes given off by aluminium phosphide tablets, was prosecuted with fines and court costs of £45,000. Breaching health and safety regulations regarding usage of the rat poison led to three employees suffering physical and mental injuries that may affect them for the rest of their lives.

Phosphorus is used in the manufacture of other rat and cockroach poisons, not only as the phosphide pastes already mentioned, but also as organophosphorus compounds.

In the past, red phosphorus was used, in the form of a 1 - 2 per cent paste, as both a cockroach poison and as a rodenticide.

White phosphorus has to be stored under water because it spontaneously catches fire with the oxygen in the air. Because of this, phosphorus should never be mixed with dry bait but should always be mixed with substances containing liquids, such as water, molasses or fat.

Due to its toxicity in humans, where as little as 15mg could be severely toxic and 50mg could be fatal, phosphorus, which was once a very popular rodenticide, is no longer recommended and now little used.

Other far more effective and less toxic rodenticides are now available. However, phosphoric acid is used widely in industry and indeed was used as an approved disinfectant in the outbreak of Foot and Mouth Disease in the United Kingdom a few years ago.

Sodium fluoroacetate is a highly effective rodenticide but is very toxic to humans and other animals, so it must be used with great caution by specially trained operatives. The toxic effects may be delayed for several hours after absorption by mouth or by inhalation. The symptoms start with nausea and vomiting, followed by feelings of apprehension with muscle twitching and heart irregularities, which lead on to convulsions, respiratory failure and coma. Death is usually due to ventricular fibrillation and the consequent heart failure.

Barium carbonate has also been used as a rat poison in the past. It is insoluble in water, but becomes highly toxic once swallowed because it dissolves in the acid in the stomach and can then be absorbed into the bloodstream. Death of the rodents then results from cardiac and respiratory failure.

Antu was another substance formerly used as a rodenticide, but it is now severely restricted in use, due to the presence of known carcinogenic impurities such as naphthylamine that are contained in it.

As with all poisonous substances, they can be used fatally, by accident or with cruel intentions. In the past, thallium-containing pastes and coated grain (such as Thalgrain) were marketed as rodenticides – and used to murder people too. One such example is Graham Young, whose tale is told in Chapter 2, as well as in the next chapter.

Bleeding rats, squill and strychnine

Warfarin is an anticoagulant that is widely used today. In medicine, it is given to patients who have had heart surgery, to prevent blood clots. It is also used by those who have had a deep-vein thrombosis (DVT), a pulmonary embolism or heart attack. Warfarin, in addition to its medicinal uses, is widely used as a rodenticide. The bait used contains a low level (about one part in 40) of the active agent. The rats are finally killed after eating about five doses. Because the bait has such a low strength, the risk of toxicity to man and domestic animals is not serious, so this type of poison can be safely left lying about on the floor.

Warfarin works by antagonising the action of vitamin K in the body. It does this by preventing prothrombin synthesis, which is vital in the blood-clotting process (described in Appendix V), and leads to internal bleeding in affected rodents. So the rats effectively become haemophiliacs, and bleed to death.

In humans, the antidote to warfarin poisoning is a large dose of vitamin K, to counteract the action of this anticoagulant. Some rats have now become resistant to warfarin, and so, for these creatures, the second-generation coumarin rodenticides are used. This type of rodenticide has only 100mg of the active agent in each kilogram of bait and so is not hazardous to humans.

These more concentrated forms are particularly hazardous, though: there have been a number of poisonings, including fatalities, with these more potent agents, and as a consequence their use is now somewhat restricted. Baits containing these powerful second-generation agents may only be prepared by trained personnel and must contain a marker dye to act as a visual warning of their presence.

Red squill is another rodenticide, and it is both neurotoxic and cardiotoxic. It is very poisonous to rats and is incorporated as an ingredient of rat pastes. It acts on the central nervous system, and it is extremely irritating to the skin so should only be handled with rubber gloves. Its use as a poison is not considered acceptable to animals other than rodents, so it is included in the Animals (Cruel Poisons) Regulations, 1963, which prohibits its use in the United Kingdom except for killing rats.

Strychnine stimulates the nervous system by reducing the inhibition that normally controls it. It is very poisonous, with large doses producing convulsions. Strychnine used to be used to kill vermin, particularly the European mole. This poison is now also prohibited under the Animals (Cruel Poisons) Regulations, 1963, which banned its use in the United Kingdom. The use of strychnine to kill moles was prohibited from September 1st 2006. This is the result of an EU directive to ensure that all currently authorised pesticides meet modern human and environmental protection standards. Two products, which both contain aluminium phosphide, are now the approved alternatives to strychnine.

Pest-killing arsenic

Arsenic trioxide was used for many years in weedkillers, sheep-dips and as rodenticides.

In 1919, in Sussex there was a case of accidental poisoning caused by a tin of liquid weedkiller that contained arsenic. The leaking tin was placed beside a sack of sugar in the guards van of a railway train. During the journey, the sugar absorbed a quantity of the leaking weedkiller, although no one noticed at the time. It was not until the sugar was later sold, and had poisoned those who used it, that the cause was finally realised.

In 1921, a lady called Mrs Hanktelow from Beckenham was killed by taking a quantity of ‘Eureka’ weedkiller, which contained about 60 per cent arsenic trioxide. A report of poisoned apples, which also happened in the 1920s, was found to have been caused by a build-up of chemicals as an incrustation on the fruit, following their spraying with a mixture of the pesticides Bordeaux Mixture (copper sulphate and lime) together with Paris Green (an arsenical compound).

Seed dressing comes undone

Mercury was used in seed dressings from the 1920s, with the intention of making the seed resistant to fungal disease. By the 1960s there were more than 150 different products on the market of the mercury type of seed dressing alone. Unfortunately, mercury is poisonous and this type of crop protection led to a number of mass poisonings in the Third World.

When seed dressings were given to Third World countries, instead of planting the grain to provide a crop the following year, as was intended, the poor and starving villagers used it immediately to make bread. The poisoning became apparent only after the bread had been baked and eaten. In northern Iraq, more than 5,000 people were poisoned in this way, and 280 of them died after eating bread made from mercury-treated grain in the 1970s.

The donating nations had supplied the seed dressing with the best of intentions, sending their gift via the World Health Organisation. Crops grown from the treated grain absorb very little of the mercury during growth and would have been perfectly safe to eat. However, as a result of the immediate use of the grain and the unfortunate and unintended poisonings, the use of mercury seed dressings is now much reduced.

Failing fumigants

Ethylene dibromide and ethylene dichloride have both been used as insecticidal fumigants. But both these fumigants are readily absorbed through the skin, causing blistering as well as kidney and liver damage. Their use has been restricted because they were found to be carcinogenic in experimental animals. There was also evidence of persistence in both fruit and cereal crops that have undergone fumigation with these agents.

Naphthalene has also been used in the past as a soil fumigant. But continuous exposure to the vapour of naphthalene led to cataract formation and then blindness in workers so this too is no longer used.

Worm-like species, the nematodes have their own pesticides, the nematodicides. Dibromochloropropane, an example of this type of pesticide, is also used as a soil fumigant. However, this substance can cause sterility in humans; both low sperm counts and evidence of testicular damage have been found in exposed workers. A substance used instead is ethylene chlorohydrins, which has a dual purpose, being utilised not only as an insecticide but also for forcing the early sprouting of potatoes.

Chloropicrin is a poison gas used to kill both insects and other parasites. It is used to fumigate and disinfect stored grain and soil. As it is a lachrymatory agent (it makes your eyes water), which is intensely irritating to the skin and mucous membranes, it has found an additional use as a warning gas when added to other even more toxic fumigants.

Mildew murder

Like pesticides, fungicides work either by direct contact or systemically. Fungal diseases such as mildew, blight and rust spread rapidly on plants once established, so treatment needs to be both fast and effective. Fungicides are now applied to both growing and stored crops as a preventative measure, either as a foliage spray or as a seed dressing.

The broadly toxic elements copper, mercury and sulphur were among the first fungicides used in agriculture. For example, the powder flowers of sulphur was used for many years by gardeners to dust over their plants to control fungal diseases, such as powdery mildew. Copper sulphate and mercury chloride were in use as long ago as the eighteenth century and lime sulphur was used to treat mildew from 1802 onwards. The well-known Bordeaux Mixture (a mixture of copper sulphate and lime dissolved in water) was also used as a fungicide for many years. These older contact type of fungicides have now largely been superseded by far more effective synthetic compounds, which work systemically.

As mentioned in the previous chapter, in the past vineyard workers who used copper sulphate sprays were found to have pathological lung changes, including blue spots on the surface of the lung, with lesions, nodules and other tissue damage. All the lesions were found to contain particles of copper. This lung damage and the resulting respiratory problems were due to progressive thickening and scarring of the tissues.

Contact fungicides kill germinating fungal spores and so prevent further infection, but they have little effect on established fungal growths; in contrast, systemic fungicides, such as benomyl, effectively kill established growths of fungi in the plant tissues. Benomyl is active against a wide variety of fungal pathogens, especially powdery mildew. It is non-toxic to animal life and so is widely used by both professional growers and amateur gardeners alike. Some fungicides can be harmful to fish, so care must be taken near ponds, streams and rivers.

Frequent use of systemic fungicides can lead to the development of resistant strains, which can sometimes be overcome by the use of a different compound; however, a better alternative is to use biological control wherever possible. Organotin compounds can be extremely poisonous but are nonetheless used as fungicides and wood preservatives.

Those wretched weedkillers

A herbicide is toxic to plants, and is used to kill weeds and other unwanted vegetation. Non-specific herbicides such as sodium chlorate and paraquat quite literally kill all plants. Selective herbicides will kill only broad-leaved plants and so are useful when growing cereals and other grass-like, thin-leaved crops. Herbicides must be used with great care, as although they are designed to kill plants, some are also toxic to humans.

Concern about persistent toxicity has led to the development of some products that break down when they enter the soil. Other herbicides have been specifically designed as pre-emergent herbicides, to persist in the soil and to kill weeds when at their most vulnerable, as they germinate. Some other specialist herbicides, while being relatively non-toxic to animal life, are widely used by farmers as selective or post-emergent herbicides to kill off existing weeds as the crop grows. These special herbicides are used on many crops, such as maize, sugar cane and sorghum, so ensuring ease of harvesting of the maximum crop possible.

Both diquat and paraquat inhibit photosynthesis non-selectively, acting as powerful contact herbicides, which are then inactivated on contact with the soil. However, if swallowed, they cause severe, often irreversible damage to the lungs, liver and kidneys. And this can be fatal: fashion icon Isabella Blow killed herself with paraquat in 2007, as detailed in Chapter 5.

The liquid concentrate of paraquat, one part in five strength, is now only supplied for agricultural use to approved users in the UK under the brand name Gramoxone. Preparations of paraquat are now formulated to contain an emetic or a laxative and some also contain a malodorous ingredient to deter ingestion. The available domestic garden product, ‘Weedol’, is only a one-in-40 solution of paraquat. This strength, though causing nausea and vomiting, as well as some respiratory changes when ingested, is not regarded as the lethal form.

Susan Barber’s husband, Michael, came home early one day in May 1981 to find his wife in bed with another man. It was Richard Collins, his partner in the local darts team. Michael hit his wife and threw her lover out. The following day, Susan put half a teaspoonful of weedkiller into her husband’s steak and kidney pie. Unknowing, he ate it, became ill and ended up in the hospital.

The doctors, not realising that he had been poisoned, suspected from the symptoms that he had pneumonia. Later his illness was diagnosed as a rare neurological condition called Goodpasture’s syndrome. He was then transferred to Hammersmith Hospital in London, where he died. The cause of death was given as pneumonia and kidney failure. His ‘grieving’ widow was able to collect £15,000 from her husband’s pension fund and she then set up home with her lover.

The pathologist who conducted the post-mortem had some lingering doubts about the cause of death and took the precaution of preserving various organs from the body. Some of these were sent to ICI, the manufacturer of a weedkiller called Gramoxone. Tests showed traces of the weedkiller in the preserved organs and the police began to make enquiries, which finally resulted in Susan Barber’s arrest in April 1982. At the trial, Richard Collins, the lover, was charged with conspiracy to murder and received two years’ imprisonment, while Susan Barber, the murderous widow, was jailed for life.

The triazine herbicides, such as simazine, a pre-emergence weedkiller, are also used as selective herbicides. Barban is a translocated herbicide used to kill wild oats without causing serious damage to wheat, barley and various legume crops. This carbamate derivative is relatively non-toxic in humans, but an allergic reaction to it can sometimes occur.

Benazolin is a post-emergent herbicide that is effective against chickweed and cleavers, and is relatively non-toxic. Glyphosate is another herbicide with which a large number of poisonings have occurred over the years. It is believed that its toxicity is largely due to a surfactant, polyoxyethyleneamine, which is included in the formulation of the proprietary product ‘Roundup’.

A final titbit

Dintro-o-cresol and dinitrophenol are interesting in that they were both formerly used as herbicides. Dintro-o-cresol, which claimed to be five times as potent as dinitrophenol, was also used as an insecticide. Their mode of action was to increase the rate of metabolism within the cells, and so, as well as their agricultural uses, they also came to be used medicinally in the 1930s as treatment for obesity. Unfortunately, dinitrophenol was very dangerous and fatalities occurred due to the induced heat stroke and swelling of the brain caused, which then led on to respiratory and cardiac failure.

Needless to say, there were many cases of poisoning, one of which is described in Chapter 14. Agricultural workers, who discarded their protective clothing when working in hot weather, were fatally poisoned, because these agents were absorbed through the unprotected skin, as well as by inhalation. There were eight fatalities among the many cases of poisoning, which occurred in a six-year period in the late 1940s. These dangerous substances are no longer in agricultural use.