Chemicals

• Author: International Labour Organization
• Pages: 66-92

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10. Chemicals

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:

– elimination;

– substitution, for example substituting a more hazardous chemical with a less

hazardous one;

– 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

worker.

10.1. Introduction

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

exposures.

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: