The control hierarchy

The hierarchy of control will help you decide the best way to control risks. The hierarchy ranks control measures from the most effective to the least preferable. However, not all types of strategies will be practicable and more than one type of strategy may be needed for best exposure protection. Methods to eliminate or control risk must be considered and adopted in the following order:

7.1.1 Elimination and reduction

Exposure to a chemical can be eliminated by removing the substance from the workplace, or by reducing its use.

For example, the use of a pesticide can be eliminated by removing the pest through manipulation of the environment. At the same time this can benefit production and the environment, including eliminating wastes.

Consider practices that involve:

• better hygiene

• removing pest breeding areas

• biological control and beneficial insects • rotating crops or alternative crop varieties • physical barriers

• biotechnology and integrated pest management (IPM) • eradication.

Use these along with pest monitoring to reduce the frequency of chemical application (this is called integrated pest management, or IPM)

7.1.2 Substitution

It may be possible to substitute a chemical for a less hazardous one. Choosing appropriate containers will help reduce waste. Examples of substitution include:

• using a less toxic chemical • using a less volatile chemical

• altering the physical form such as replacing an emulsifiable concentrate formulation with a granular

formulation or encapsulated product to reduce the handling risks

• purchasing only returnable or reuseable containers. 7.1.3 Isolation

Isolation of the process can be achieved by distancing it from the rest of the workplace or by a physical barrier between the process and any person. Examples of isolation include:

(a) separate areas used for storing, mixing and preparing pesticides with limited access to all but properly authorised employees.

(b) using an air-conditioned truck or tractor cabins with properly functioning and maintained activated carbon filters designed to remove pesticide vapours.

(c) carriage of chemicals in a section of a vehicle isolated from the driver and passengers during transport.

(d) storage in a separate building or fenced area. (e) fencing off a contaminated dip site.

(f) closed chemical transfer systems which reduce the risk of contact with concentrate (eg induction hoppers, direct injection).

If using an air-conditioned cabin, observe the following precautions: Check door seals for wear. Keep windows, doors and hatches or vents closed and air-conditioning on recycle during operations. Carbon filters must be maintained properly. Consider wearing a respirator if a carbon filter is not available. (At present there is no Australian Standard applying to vehicle carbon filters). The use of air-conditioning without carbon filters on “recycle” could contaminate the cabin over a period of time.

7.1.4 Engineering controls

An engineering control is a system which:

• minimises the generation or emission of a chemical • suppresses or contains a chemical

• delivers the chemical in a way that reduces misting.

Types of engineering controls include the choice of application equipment, a local extraction ventilation system or an automated process. Consider engineering controls for indoor work if air contamination is likely, for example in a green house or packing shed.

Examples of engineering controls include:

• using an extraction ventilation equipment (ventilator) over a fruit dipping bath to remove solvent

vapours

• changing nozzles to control droplet size or spray pattern

• using a purpose designed workplace with good natural or mechanical ventilation (to provide adequate

7.1.5 Administrative controls and work practices

Administrative controls are planned work practices which enable you to manage risks. These include: the time of work, hours of work restrictions, taking wind and weather conditions into account, and restricting who does the work and who has access to a work area or chemical store. Administrative controls are implemented to ensure safe work practices are adopted in the workplace and that environmental impact is minimised.

Examples of administrative controls include:

(a) Reducing the number of persons exposed and excluding non-essential personnel from the area. For example, treat a building when not in use. Minimising the number of workers during dipping. Delay grain unloading and entry into silos for a period following fumigation.

(b) Limiting the time period of exposure for an employee.

(c) Prohibiting eating, drinking and smoking when handling chemicals.

(d) Providing and ensuring the use of adequate facilities for effective decontamination such as washing facilities.

(e) Ensuring that outdoor tasks are done at the most appropriate time of day (eg wind drift or heat stress).

(f) Correctly calculating crop volume, area to be treated and amount of spray required. This has the added benefit of minimising the amount used and costs.

(g) Correctly calibrating equipment

(h) Restricting crop re-entry after spraying (see section 8.6) (i) Signs indicating hazards.

(j) Notification of neighbours.

(k) Establishing procedures for disposal of waste and containers.

7.1.6 Personal Protective Equipment (PPE)

PPE should only be relied upon where it is not possible to control exposure by one or more of the above measures. PPE should be used:

• according to instructions on the container label

• in an open field situation where engineering controls are not available • when mixing, decanting or spraying

• in some circumstances as a back-up for other control measures.

Employers must provide PPE to workers free of charge.