Most exposure to crop protection products by operators is when:
Mixing and weighing out
Working with a leaking sprayer
Mixing and preparing undiluted products
Always maintain high standards of hygiene when working with crop protection products.
Work in an area away from children and animals.
Avoid any risk of polluting water courses
Ensure you understand the product label information: especially product dose rate and safety requirements when mixing and preparing the product.
Only use dedicated equipment for measuring and weighing products: Do not use food containers or cutlery
Wash all equipment and empty containers after the spraying job is completed.
Be forestarting any spraying activity always:-
Read and understand the product label
Check the sprayer for leaks
Ensure you have the correct PPE
If you feel unwell then do not work with pesticides
Never mix products or fill sprayers close to water courses, wells or where products could get into ground water.
Never decant products into other containers.
Always dispose of empty packaging and other contaminated waste following best practice.
Decisions on operator exposure are based on a comparison of the No Observed Adverse Effect Level (NOAEL) and an estimate of human exposure.
The Acceptable Operator Exposure Level (AOEL) is derived from the NOAEL by dividing it by an assessment factor (usually by a factor of 100, which is essentially made up of two ×10 uncertainty factors (Anon, 1999a; Renwick, 1991) to allow for inter- and intra- species variation, as discussed in previous units.
In some countries, such as the USA, the margin of exposure (MOE) or margin of safety are derived in a similar manner.
As it would be impossible to measure the exposure in all situations, there is considerable reliance on experimental data obtained from particular usage situations that have been incorporated into generic models such as the European Predictive Operator Exposure Model (EUROPOEM; Gilbert, 1995), which is still being developed.
The impact of exposure will also be affected by the frequency of exposure. In Holland, the use of insecticides and fungicides was more frequent than the use of herbicides as they were used ten to twenty times a year on the most intensively treated crops, but single pesticide products were not used more than seven times a year (van Droogeet al., 2001).
In that study, ornamental crops such as chrysanthemums were treated more than arable crops. Some spray operators, such as those employed by contractors will be exposed for more days per year than individuals on small farms.
Potential Dermal Exposure
This is the total amount of pesticide landing on the body, including clothing, but the actual exposure of the skin will depend on the amount deposited directly on the skin plus any that penetrates clothing and is therefore available on the skin for absorption into the body.
Operator exposure is significantly reduced by wearing protective clothing. The basic requirement is good overalls of closely woven fabric. In temperate climates, impermeable materials are suitable and in many cases operators use disposable overalls made from a polypropylene material.
Although this eliminates the need for laundering, such overalls are generally considered to be too hot to wear in tropical climates, and do not always provide as much protection as those made from cotton (Moreira etal., 1999).
Various special finishes to cotton fabrics have also been tried for use in tropical countries. Laundering of garments does not always remove the entire pesticide residue in a garment. Nelson et al. (1992) reported that the percentage not removed could vary from 1% to over 40%.
However, in the tropics some degradation will occur when the garments are exposed to sunlight (Shaw et al.,1997). The washing of used protective clothing may also cross-contaminate other garments.
Wearing an apron of impermeable plastic, especially when opening pesticide containers, will protect the overalls from splashing during preparation of sprays and can be readily removed while spraying.
Similarly, a face shield is also recommended during mixing to protect the face, and especially the eyes. Some countries prefer to recommend goggles but these do not protect the face.
When suitable overalls are not available or are too expensive for small-scale farmers, the area of exposed skin should be minimized by wearing long trousers and a long-sleeved shirt.
These need to be removed and washed separately from domestic laundry as soon as possible after a spray application has been completed.
Exposure of Hands
The hands, inevitably, are the part of the body most exposed to pesticides, due to handling of containers and when operating equipment.
Data from PHED indicates that a person mixing and loading pesticide in the USA can be exposed to 6300 μg/kg ai when not wearing gloves compared to only51.1 μg/kg ai when wearing gloves (Fenske and Day, 2005).
The type of exposure will depend on many factors, but in the worst case the whole hand could be coated with liquid.
Substances can be removed from the surface of the skin (especially the hands) by using swabs or towels, moistened with a solvent, such as 95% ethanol. The technique does not indicate what could have been absorbed before the skin was washed.
To protect hands, the wearing of impermeable gloves is recommended, but these vary in their thickness and suitability, especially when adjusting small parts such as nozzles.
Gloves with a cuff long enough to be covered by the end of the coverall sleeve are advised so that any liquid, or granule, that is on the arm does not pass down inside the glove.
Neoprene and nitrile gloves provide protection to a range of solvents and oils, and are suitable when using emulsifiable concentrate and similar liquid formulations. Nevertheless, users should wash off any pesticide as soon as possible as some chemicals can penetrate a glove.
Care is needed when washing gloves, as the rinsate subsequently acts as a source of exposure for other workers or family members, water courses, etc. Often, contamination of the gloves occurs when the operator removes the gloves using a clean hand to remove a dirty glove.
Washing the gloves before removal is advised, but care is still needed when removing the glove. In some situations, especially in the tropics, an impermeable glove causes the hand to sweat and this may increase the risk of absorption.
Spray operators not using gloves should only apply the less hazardous pesticides and have a bucket of water readily available so that a bare hand that has been exposed to spray can be washed immediately.
In the open air, the risk of inhaling spray droplets is extremely low. Most sprays contain only a small fraction of the volume in droplets smaller than 100 μm.
While these small droplets can shrink, especially on hot days and with low humidity, the smallest droplets in the range of 1–10 μm that could be inhaled are readily carried downwind and away from the spray operator.
Any larger droplets close to the nose may be deposited on the face or filtered within the nose, and would not reach the lungs. The situation is different when applying pesticides inside buildings, stores and glasshouses where small droplets can remain airborne close to the operator.
The main concern with inhalation exposure is when pesticides are applied as fogs, where a high proportion of the droplets are below 25 μm. It is essential to wear the correct respiratory protection equipment (RPE) when fogging, especially inside buildings.
The main item is a respirator, which has a filter to remove the very small particles of pesticide in a fog. The correct filter, depending on the chemical being applied, must be fitted and replaced according to instructions.
Inexpensive disposable masks are not respirators and often merely reduce the impaction of spray droplets directly on the skin around the nose and mouth.
Some more expensive protectors which cover the operator’s head may not be true respirators but have a pump to draw air through the filter and blow the filtered air over the face.
The feet should always be well protected by wearing ‘rubber’ boots or equivalent, with the bottom of the trouser legs placed over the boot so that liquid or granules do not fall into the boot. In some areas spray operators fail to wear shoes, but if they do so the shoes are often of very poor quality and made from absorbent materials.
The ears should always be protected when the noise of the operating spraying equipment exceeds 85 decibels. This applies especially to manually carriedmotorised equipment fitted with a two-stroke engine, and when pulsejet fogging equipment is used.
If a spray operator becomes ill, while working, the doctor must be informed of the name of the active ingredient and given as much information as possible by being shown a leafl et or label about the chemical being used.
Treatment by a doctor will depend very much on the type of poisoning. When using an OP or a carbamate (anticholinesterase), an injection of atropine is useful, but suitable antidotes for organochlorine poisoning are not available.
A person who has ingested liquid that contained paraquat can be treated by their ingesting large quantities of Fuller’s earth, which adsorbs the herbicide. Morphine should not be given to patients affected by pesticide poisoning.
A first-aid kit and a supply of clean water for drinking and washing any contaminated areas of the body should be readily available. On large- scale spraying programmes fi rst-aid kits should be carried in vehicles and aircraft. People regularly involved in applying OP pesticides should undergo routine medical examinations in order to check cholinesterase levels in their blood plasma.
In conclusion, it is obvious from the foregoing, that adequate knowledge of, as well as strict adherence to the safety measures suggested will go a long way to minimize the attendant risks accrued to pesticide transport and use.
Legislative bodies should therefore make it a point of duty to provide adequate education to the handlers of plant and animal protection chemicals relating to the safety of human and the environment.
These bodies should also ensure/enforce compliance to the safety measure by users of pesticides. This will not only ensure access to healthy food but will also guaranty a near safe environment.
The safety measures to accompany transportation of pesticide from one location to the other;
The things to do and not to do while using any of the past control chemicals available for use in crop and animal protection;
The various ways a pesticide applicator may be exposed to pesticides, the degree of exposure; and
How to protect the various body parts through which pesticides can gain entry into the body.