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The widespread use of agrochemicals in agriculture worldwide requires rigorous
control to prevent serious health risks to employers, workers and the general public. Sound
management of chemicals and the deployment of the full hierarchy of controls are needed
to minimize occupational exposures, as follows:
– substitution, for example substituting a more hazardous chemical with a less
– engineering control measures, for example a well designed system for storage and
dispensing of pesticides;
– administrative controls such as restricting entry into enclosed areas that have been
sprayed with pesticides;
– as a last resort, provision of personal protective equipment (PPE) that is suitable for
the worker and appropriate for the task and affords adequate protection. PPE is not a
substitute for control strategies to eliminate or minimize the potential hazard to the
10.1.1. Pesticides are the chemicals of greatest concern in regard to health and
safety in agriculture. Pesticides are categorized according to their use, and include
fungicides, herbicides, insecticides, larvicides, miticides, molluscicides, nematicids,
ovicides, piscicides and rodenticides. Other chemicals classed as pesticides include
attractants, chemosterilants, defoliants, desiccants, disinfectants, growth regulators,
pheromones, feed attractants and repellents. Other chemical exposures can occur in
agriculture, as indicated below, but are not discussed in this section.
10.1.2. Fertilizers that are a toxic hazard for workers can cause skin irritation and
potentially serious respiratory effects through the inhalation of gaseous forms of anhydrous
ammonia. Care should be taken when handling fertilizers to minimize exposures.
10.1.3. Some veterinary products including veterinary medicines have toxic
properties and workers who handle these products may be exposed to them. Care should be
taken when handling veterinary products to minimize skin exposures.
10.1.4. Animal emissions, such as ammonia and methane, are eye and respiratory
irritants, so care should be taken when workers enter closed spaces (see Chapter 16).
10.1.5. Exhaust from fuel-powered equipment, including diesel, is a significant
respiratory hazard and worker exposure should be minimized (see Chapter 14).
10.1.6. Gases formed during crop storage can be toxic and may pose a risk to
workers in confined spaces. Care should be taken to ventilate such spaces prior to entry,
and to wear proper respiratory protection (see also Chapter 14).
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10.1.7. Integrated pest management in which several modalities are used to control
pest infestations such as chemical crop protection agents, cultivation techniques, biological
controls, crop or pasture rotations, and/or other practices, may be useful in reducing
10.1.8. Pesticides and other hazardous chemicals might be used in ways that have
the potential to be a risk not only to workers, but also to the population in the vicinity of
the use of the chemicals and to the general environment. The use of such chemicals should
additionally be controlled in accordance with any relevant environmental protection
measures required by national law and practice or international standards.
10.2. Hazard description
10.2.1. Routes of exposure
10.2.1.1. Absorption through the skin is the primary route of exposure for most
widely used insecticides, fungicides and herbicides. At normal exposure levels, skin
damage or other symptoms may not be noticed, so absorption occurs without the worker’s
knowledge. The distribution of skin exposure will be determined by the particular work
tasks. Exposure can occur to the whole body during spraying. Exposure to the hands
occurs in nearly all cases. Forearm, torso and facial exposure are common during mixing,
loading and hand spraying. Exposure to the torso is likely when workers carry chemicals
on their backs, as with backpack sprayers. Exposure to the legs can occur through contact
with recently treated foliage, as is common in greenhouses or in fields with minimal
spacing between crop rows. Intensity of skin exposure will be determined by the frequency
of contact or activity, and by the pesticide-active ingredient concentration in the applied
material and whether equipment, including PPE, is being used correctly. Certain groups are
particularly vulnerable to absorption through the skin. These include women, particularly
pregnant women, young persons, children and those with more body fat.
10.2.1.2. Inhalation is an important route of exposure when working with volatile
compounds or in enclosed spaces such as greenhouses. Gases and vapours are readily
inhaled and absorbed in the respiratory tract. Small particles (10 microns or less), including
water droplets can also be inhaled. Pesticides can volatilize from treated leaves and soil,
posing a hazard to re-entry workers.
10.2.1.3. Ingestion is another route of exposure for pesticides, and can be a
significant contributor to dose if food or cigarettes are handled after contact with pesticides
and prior to washing (see 10.3.6.1).
10.2.2. Principal health effects
10.2.2.1. Acute health effects
10.2.2.1.1. Pesticides produce acute health effects when signs and symptoms of
poisoning occur shortly after exposure, normally within 24 hours. These effects may be
either local or systemic. Local effects are those that occur at the point of contact, as is the
case with skin and eye irritation. Systemic effects require absorption and distribution from
the entry point to other parts of the body.
10.2.2.1.2. Based on the risk of single and multiple exposures over a short period of
time, acutely toxic pesticides normally fall in the top three categories within the World
Health Organization’s classification of pesticides by hazard: extremely hazardous (Ia),
highly hazardous (Ib), and moderately hazardous (II). Most insecticides fall into these
categories, whereas most fungicides and herbicides fall into the less hazardous categories: