Agrochemicals are also applied as veterinary products, fertilisers and commodity chemicals. The precautionary measures described earlier also apply to these types of product. Different methods of agrochemical application will, however, require further consideration of risks to the user. Precautions as illustrated by the following examples should be taken:
– Animal injection treatments occasionally result in skin grazing or self-injection of the handier. Prevention requires patience and care with excitable animals. A needle set in a retractable spring-loaded sleeve which protects against accidental contact should be used.
– Animal dips for sheep or cattle are a site of intense activity and contamination. There is often much physical handling of livestock together with the splash of immersion and the cloud of spray from the animal shaking itself on exit (figure 23). The agrochemical in use generally requires a basic level of personal protection (figure 24). In addition, any person working at the site of exit might require some respiratory protection. Alternatively, a rota system of working on short shifts should be arranged.
– Hydrofluoric acid is used to clean debris and moss growth from the roof surfaces of glasshouses. Application may be by means of a brush or by spraying from a knapsack sprayer. In such instances, personal protection appropriate to work with strong acids is necessary (figure 25). Formalin liquid is made to react with potassium permanganate to produce formaldehyde gas as a fumigant. This is a common treatment against disease-causing organisms present in some livestock buildings. The main precaution is in the mixing, which requires the measured amount of potassium permanganate to be added (last) to the required quantity of formalin; never the other way around, because the reaction and heat generated would be particularly violent.
– Strychnine and cyanide may, in certain exceptional circumstances, be approved for the control of pests such as moles or rabbits. The agrochemical is usually released underground. These extremely toxic substances should be used only by those thoroughly trained in all aspects of the work and the precautions to be observed.
– Fertilisers supplied as granules or naturally occurring rock powders may be applied by hand or by tractor-drawn machine. Applying fertilisers by hand should be avoided by using a shovel or spade. If handling is unavoidable, suitable protective gauntlet gloves may be needed.
– Liquid fertilisers are used in modern horticultural units where plants are reared hydroponically under glass roofs and individually fed through an arrangement of flexible pipes from a liquid mix and metering control unit. The concentrate may include products such as nitric and phosphoric acid which will require the handler to be protected against acids which can burn the skin. When opening acid containers, precautions should also be taken to disperse any gaseous fumes safely.
– Silage additives often include acids such as formic, phosphoric or sulphuric acid. Application is generally from a sprayer unit attached to the forage harvester. Appropriate personal protection is necessary when handling strong acids.
13.7 Spillage
Agrochemical spillage is both wasteful and hazardous. It should be avoided wherever possible but when it occurs it should be dealt with immediately. Some common causes of spillage are:
– containers bursting as a result of bad handling;
– container leaks due to defective packaging that does not withstand heat or humidity;
– containers being punctured during transport by sharp edges or metal studs protruding upwards through vehicle floorboards;
– careless pouring while transferring from container to applicator;
– equipment failure prior to or during application because of worn pipe couplings or hose lines. Action in the event of spillage should include:
– taking immediate steps to avoid the spillage spreading and contaminating a wider area;
– keeping other people, animals and vehicles away from the site;
– wearing protective clothing appropriate to the use of the concentrated formulation involved;
– soaking up the agrochemical with absorbent material such as dry sand, soil or wood shavings in the case of a liquid, and removing the contaminated matter with a brush and shovel and storing securely in a bag to be disposed of safely bathing or thoroughly washing immediately afterwards.
13.8 Disposal of containers and waste
There will be circumstances when agrochemicals in store need to be disposed of safely. They may no longer be required or may be out of date, or the packaging may be broken or the container damaged. Similarly, deposits of spillage clean-ups, discarded items grossly contaminated with agrochemicals, contaminated aqueous waste such as animal dips, and empty containers must be disposed of safely.
The following general steps should be observed during disposal of waste:
– Agrochemical waste should never be dumped indiscriminately.
– Agrochemicals should never be disposed of so as to cause any risk to people, animals, crops, water supplies or the environment.
– First of all, the supplier should be asked if he would accept the waste for disposal.
– Whenever possible, waste should be disposed of through a company or persons licensed to handle waste disposal. Advice should be sought from the supplier, local authority or community leader.
– Accumulation of waste should be avoided. Waste should be disposed of as soon as possible.
– The user should read the label on the package or container for any specific advice on waste disposal.
– Empty agrochemical containers should never be reused except possibly, if in good condition, to contain an identical product transferred from a deteriorated or leaking container. All other containers should always be cleaned thoroughly before disposal. They may be cleaned in accordance with the labelled instructions. In the absence of instructions, rinse the containers in water successively at least three times. Care should be taken to ensure that the water used for rinsing does not contaminate the environment; particularly drinking-water, for example.
– Liquid containers should be drained out before cleaning. Ideally cleaning should take place when a spray mixture is being prepared so that the drained material and the rinsing liquid can be added to form a part of that mixture. In other instances the rinsings should be collected for subsequent disposal elsewhere. After cleaning, the containers should be punctured in several places or crushed to make them unusable, and stored in a secure compound until their disposal is arranged. Packages of dry powders and granules must be shaken out thoroughly into a mixing vessel or the applicator tank.
– Containers may be buried on premises owned or occupied by the agrochemical user. The burial site must be chosen carefully so that there can be no risk of pollution to surface water or groundwater. The approval or the advice of the local authority should be sought beforehand. The containers should be buried to a depth of at least 1 metre below the surface and below the level of any land drains (figure 27). The area used should be fenced or marked with warning signs. A record should be kept of the dates and the material buried.
During burial of waste, protective clothing appropriate for the most hazardous product handled should be worn.
– Containers in which hydrogen cyanide gassing powders or aluminium, magnesium or zinc phosphides were supplied, or which have contained these materials, should not be rinsed or cleaned with water when empty. These substances react with
13.9 Operational control
Agrochemical users must make every effort to use those products that minimise the risk to themselves and others. In the choice of agrochemicals they may often be guided by advertisements in the mass media. It is therefore important that users seek advice from agricultural extension workers and several independent suppliers. Similarly, choice of safe technology is important. For example, there may be several types of spray equipment on the market, but the cheapest ones are often not the best for safety. They may be of poor quality and might start to leak. The same may be true of the choice of personal protective equipment. Again, users should remember to seek advice.
The adoption of safe working systems and practices will minimise risk. Some of these have already been discussed in sections 2.3.6 and 2.3.7. The arrangement of working time, particularly in hot climates, would be relevant here. For example, agrochemical spraying could be undertaken in the early hours of the morning. Engineering control measures, personal hygiene and other measures, the use of personal protective equipment as a last line of defense and the alternatives to agrochemicals will be discussed in the following subsections.
13.9.1 Engineering control measures
A basic principle of user protection is that all possible measures should first be taken to reduce exposure at the source. Routine maintenance should ensure that agrochemical application equipment is in good condition and without any potential to leak or spill. Particular attention should be given to knapsack sprayers where leakage could seriously contaminate the user. Figure 30 shows how they have been made safer to use by improved design that incorporates engineering control measures. New developments in engineering controls go much further by introducing improved design features which automate agrochemical handling or make some tasks easier or safer. Figure 31 shows the design of a trailed crop sprayer (also known as a tractor-drawn sprayer). Examples of engineering control measures include:
13.9.2 Personal hygiene
Personal hygiene aims to keep the body clean and not allow anything harmful to remain on it for long periods as it can be absorbed through the skin. It is equally important to avoid inhaling or ingesting small, even minute, quantities of agrochemicals because of their harmful effects on health.
The basic rules of personal hygiene in using agrochemicals are as follows:
– avoid exposure to agrochemicals by following safe practices and using protective clothing and equipment when necessary;
– thoroughly wash exposed parts of the body after work, before eating, drinking or smoking, and after using the lavatory;
– examine the body regularly to ensure that the skin is clean and healthy;
– provide a protective dressing to any part of the body where there are cuts or sores;
– avoid self-contamination at all times, particularly when decontaminating or removing protective clothing; never attempt unsafe practices, such as blowing through sprayer nozzles to unblock them (always use a soft probe);
– do not carry contaminated items such as dirty rags, tools or spare nozzles in the pockets of personal clothing;
– remove and wash separately any contaminated item of personal protective clothing daily (figure 35);
– keep finger-nails clean and short;
– avoid working with any product which causes an allergic response such as a skin rash
There are other hygienic measures to be observed:
– even if the product label does not recommend wearing protective clothing, remember to cover as much of the body as possible with lightweight clothing, e.g. long-sleeved shirt; hat or towel on head; long trousers made of cloth (rather than of plastic or similar material that might cause discomfort);
– as protective clothing is uncomfortable to wear and work in, seek advice about agrochemicals that do not require the use of protective clothing. Read the label before purchasing and ask the supplier.
13.9.3 Use of personal protective equipment
Most agrochemicals present a risk to the user which may be controlled by engineering control measures. Where recourse to the above measures does not suffice, personal protective equipment should be used.
Protective clothing
Because of the nature of farm work, engineering control measures may not always be feasible. Protective clothing therefore remains a necessary part of working with agrochemicals. The items required will depend on the harmful effects of the agrochemical and the way in which it is used. In practice, labelled information supplied with the agrochemical will generally specify the level of protection required. Detailed information on the quality of various items such as the minimum thickness of gloves or the material from which they are made, e.g. neoprene, nitrile or butyl, may also be supplied. Similarly, prescribed items of respiratory protective equipment and the care necessary in their maintenance might be listed. Examples of personal protective clothing are given in figure 36, and clothing and equipment necessary when working with highly toxic agrochemicals are shown in figure below
Head protection
Head protection may be provided as a single garment or as part of a coverall or of a face shield with hood. The advantage of such a combined garment is to ensure protection around the neck or to prevent agrochemicals spilled on the hood from soiling the work clothing worn underneath. Head protection should cover all parts of the head above the shoulders, with the exception of the face. The material used should be resistant to penetration by agrochemicals.
Eye and face protection
A face shield covering the whole of the forehead and face to a point below the jaw should be worn to protect against accidental splashes of dangerous liquids during opening or pouring from containers. Non-fogging goggles resistant to chemicals should be worn when handling dusts or granules
Respiration protection
Respirators may be half-faced, covering nose and mouth, or full-faced, covering nose, mouth and eyes. Their function is to prevent the wearer from inhaling hazardous agrochemicals. A filtering medium on the respirator removes the hazardous substances by absorption, adsorption or simple filtration. Filtration is by a simple gauze pad. In the case of highly hazardous agrochemicals, the air is filtered through a cartridge or canister containing other chemical substances that would absorb or adsorb the highly hazardous agrochemicals. Good respirators are manufactured to comply with national standards in several countries. The user should, however, ensure that the respirator provides a good fit around the nose and mouth and that he or she has received sufficient information and training on correct use and maintenance. The cartridges must be renewed periodically and the masks must be replaced regularly to ensure protection.
Protective gloves
Gloves are required when handling concentrated agrochemicals, particularly pesticides. These are very commonly absorbed through the skin or cause damage to the skin by burning. They should be at least 0.4 mm thick while retaining flexibility for simple manual tasks such as opening containers or changing nozzles. The type of glove for a particular operation will depend on the agrochemical and the length of time in contact. For example, gloves of wrist length may be required for conventional spraying of toxic pesticides, elbow length for handling granules, and shoulder length for dipping plants in pesticides. A pesticide formulation with organic solvents such as xylene will require a glove of much higher-quality material because of its capacity to penetrate protective garments.
Working clothes
Working clothes are items of personal clothing worn at work, while using agrochemicals, in this instance. They include such items as shirts, trousers, skirts, socks and shoes or boots. There will be many occasions when working clothes will be the main skin covering, e.g. when using low risk products or treating an animal. Working clothes used at work with agrochemicals should be kept clean by washing immediately after use. Wearing clothes contaminated with agrochemicals may result in poisoning or skin irritation. There have also been cases where flammable substances, such as sodium chlorate, deposited on clothes have ignited during cigarette smoking to engulf both clothing and the wearer in flames.
In general, working clothes should:
– fit comfortably so that free movement of the body and limbs is possible without undue restraint;
– be worn by the same person each day and not exchanged between individuals;
– be in good condition, sewn or mended when necessary;
– be clean and free of agrochemical deposits. Soiled work clothing should be cleaned separately from the family wash;
– be worn under protective clothing so that it is completely covered and not exposed to accidental contamination;
– be stored separately from protective clothing so that cross-contamination is avoided.
13.9.4 Selection, use and maintenance of personal protective equipment
When specified on the product label, the selection of appropriate personal protective equipment, its use and maintenance are essential for the protection of a person using hazardous agrochemicals. Advice should be sought (figure 38) and particular attention paid to the following:
- Resistance to agrochemicals. Protective clothing is produced in a variety of materials with varying capacity to resist penetration. The user should seek advice and select the appropriate ones by reading the instructions on the label or asking the supplier. In general, garments such as gloves made from neoprene, nitrile or viton material of at least 0.4 mm in thickness are resistant to most agrochemical formulations. Similarly, boots and aprons which are intended to resist contamination by concentrates should be equally resistant. Coveralls should be impermeable to liquids if subject to high levels of contamination, e.g. when the user is beneath the trees while spraying “top fruit”. If exposure is limited to occasional liquid spills or to dry powders or granules, a coverall made of a fabric material such as treated cotton or polyester may be sufficient.
Choice of garments. Some garments, such as gloves or hats made from cotton, canvas, felt or leather, are particularly unsafe for use as protective equipment during work with very hazardous agrochemicals because they absorb liquids. These liquids in turn are absorbed through the skin of the wearer, resulting in poisoning. Clothing may also be unsafe because of repeated use which may wrinkle the protective surface, allowing liquids to seep through: it should be discarded as soon as a defect becomes noticeable. Some protective clothing is intended for other purposes, such as gloves for protection against detergents at home or in the kitchen. This type of clothing may be unsuitable for work with very hazardous agrochemicals, and advice should be sought.
Tailoring. Garments should preferably be made to measure, or ready-made ones should be well selected so that seams or welded joints do not pull apart or allow liquids to enter through stitch holes. There should be no trap points which hold agrochemicals and all pockets should be inside the garment or absent altogether. Garments should provide a good cover to those parts of the body which they are intended to protect. They should also allow freedom of movement to the wearer.
– Correct matching. In practice, several items of protective clothing are often worn at the same time. Each should be a correct match with the other in providing continuity of protection between, for example, a hood overlapping the shoulders of a coverall, the sleeves of the coverall overlapping gloves, and an apron overlapping boot tops.
– User friendliness. Protective clothing should not prevent the wearer from carrying out the necessary tasks associated with agrochemical work. Gloves should not be so big or rigid that the fingers cannot be manipulated to replace a sprayer nozzle. It should be possible for the wearer to move freely without being hindered by the sheer bulk or poor design of any garment. Similarly, garments should not be unduly heavy or hot when worn. Those for use in tropical countries should wherever possible be of lightweight material and coloured white or yellow so as to reflect heat. Users should learn how to select the appropriate protective equipment.
– Washability. All garments used at work with agrochemicals should be washable without any substance being retained in “trap points”. Absorbent garments such as untreated cotton may be particularly difficult to clean completely.
– Suitability. Each item of protective clothing should be suitable for its circumstances of use. Respirators, in particular, should be of a type approved by a responsible authority. They should be fitted with the appropriate cartridge or filter to give protection against the particular hazard. There are many different types of respirator. These include (a) those which are disposable and give protection against dust, fumes and mist; (b) chemical cartridge types; (c) canister types; (d) fully self-contained types; and (e) airline breathing units. The safe use of respirators depends upon a thorough knowledge of (i) how to wear them correctly; (ii) recognising that they fit the worker accurately; and (iii) the precautions to be observed. The user should receive specific training in all these aspects. There may be circumstances where there would be a choice of garments. These may include gauntlet gloves in preference to the shorter hand gloves, hats with broad rims or hoods, and goggles which are non-fogging. Advice should be sought.
– Making a clean start. Clothing to be worn at the start of each day should be clean, dry and in good condition. The various items should be checked for signs of wear and tear and repaired or replaced as necessary.
– Wearing correctly. When gloves are worn with an impermeable coverall, it is good practice to wear the cuffs of the gloves inside the shirt sleeves so that run-off of liquids sprayed does not drip inside the gloves. Similarly, the legs of coveralls should normally be worn outside boots so that run-off drips outside. Other garments should also be worn properly. This may include the correct fastening of buttons and zips and having face shields properly lowered into position (figure 39).
– Decontamination after use. Gloves and boots should be washed before removal to avoid self-contamination (figure 40). They should then be removed and the inside should be thoroughly washed with water and detergent, rinsed and allowed to dry. Goggles and face masks should be similarly washed and allowed to dry.
– Safe storage. Protective clothing should be stored in a clean, dry, well-ventilated room separate from other clothing or living accommodation (figure 41). The FAO Guidelines for personal protection w