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Chemicals In The Workplace

Published: 04th Jul 2013 in OSA Magazine

The Workplace Safety and Health Council investigate occupational chemical hazards.

We live in a world of chemicals. Chemicals, in the form of solid, liquid or gas can be found in many places – not just at work – but in our homes as well. From plastics, detergents and paints, to food preservatives and cooking gas, the use of chemicals makes our lives easier and more comfortable.

Unfortunately, many chemicals are hazardous. Those found in workplaces such as chemical plants, laboratories or chemicals storage facilities may vary greatly in both type and quantity, and extra caution is needed when handling a hazardous chemical.

Risk assessment will help to identify the hazards posed by a chemical. Strategies for chemical risk assessment include referring to the safety data sheet, inspecting the premises, carrying out a job safety analysis and reviewing past incident and injury records.

Workers tasked with handling a particular chemical substance as part of a work activity must be made fully aware of the hazards they are facing. Every worker needs to be adequately protected from each hazard through appropriate control measures and personal protective equipment (PPE) prior to commencing the work.

A common misconception is that protection from chemicals is all about the use of PPE.While the use of PPE is important for protection against direct contact with chemicals, emphasis should be on risk reduction at source, so that the chances of contact with a hazardous chemical can be either eliminated or minimised.

Hierarchy of control measures

Before considering the use of PPE as a solution for protection against the hazards posed by a chemical substance, it is important to review the following hierarchy of control measures, starting with elimination and substitution.

Hierarchy of control

The first question that needs to be asked is whether the use of a particular hazardous chemical is absolutely necessary. If the chemical is removed from the system, can the manufacturing process proceed, or can it be substituted with something less hazardous?

If elimination or substitution is possible without significantly affecting process operations and/or product quality then priority is to first exercise these options, as this would make the system inherently safer. Eliminating or substituting the chemical would immediately render the workplace free from the hazards posed by the chemical substance in question.

An example where hazardous chemical elimination or substitution has been successful is the elimination of elemental chlorine for the bleaching of wood pulp. The use of non-chlorine bleaching agents such as oxygen, peroxide or ozone, means that the paper bleaching process can be totally chlorine free. By avoiding the use of gaseous chlorine, not only does the workplace become immediately safer, but the production of the carcinogenic and environmentally polluting chemical chlorinated dioxin is also completely eliminated.

If elimination or substitution is not possible, for example, if the chemical is a critical reagent, then the use of engineering controls such as a cooling water system for temperature control; the use of local exhaust ventilation for the removal of toxic vapours; and/or administrative controls such as safe work procedures, warning signs and proper labelling should be put in place.

In the event that all the above control measures fail, the use of PPE serves as the last line of defence against direct contact with the chemical substance. PPE may also be used as a short term contingency during maintenance, repair and emergencies, or as an additional protective measure against residual risks.

Hazard management

In the event that the use of hazardous chemicals is unavoidable, a programme to manage the storage and handling of such chemicals can be implemented to prevent or minimise workers’ exposure to the chemicals.

To protect against hazardous chemicals in the workplace, companies are strongly encouraged to establish and deploy a Management of Hazardous Chemicals Programme (MHCP).

Introduced in 2011, the MHCP for Singapore comprises 13 key elements:

• Policy and strategy
• Selection and procurement
• Register and safety data sheet (SDS)
• Labelling and warning signs
• Storage and transportation
• Risk assessments and control
• Safe work procedures and PPE
• Workplace monitoring and surveillance
• Information and training
• Emergency planning and first aid
• Waste disposal
• Contract work
• Programme review and audit

In general, the MHCP applies to all workplaces that use, produce, store, transport or handle hazardous chemicals.The MHCP should be an integral part of the safety and health management system for companies. It is especially critical for workplaces such as oil refineries, petrochemical and pharmaceutical plants, semiconductor wafer manufacturing plants, and any premises where hazardous chemicals are stored in large quantities.

Hazard communication

A critical aspect of a MHCP is the communication of hazards.This begins by having a register of all the hazardous chemicals present at a worksite, together with the SDS for each chemical on the register.Workers should be provided with easy access to such information; for example, through hard copies onsite or an online database, and be sufficiently trained to understand the contents of an SDS. Protection from chemicals in the workplace begins once the workers are aware of the hazards associated with daily work activities, and have received the necessary instruction to adopt the precautionary measures that must be taken to either prevent direct contact, or minimise exposure.

The use of warning signs and container labelling is another important way to convey hazard information to users at the point of contact with a chemical. As such – whether large or small – all containers of hazardous chemicals should be affixed with an appropriate label which should minimally contain the chemical identifier, an indication of the hazards posed by the chemical, such as through a hazard pictogram, and a precautionary signal word such as ‘warning’ or ‘danger’.

With the chemical identifier, users may then refer to the SDS for more information, including the recommended precautionary measures for safe storage and handling, as well as the appropriate engineering controls and PPE.

To ensure effective communication between chemical manufacturers, suppliers and end users, Singapore has elected to adopt the Globally Harmonised System of Classification and Labelling of Chemicals (GHS).This is guided locally by Singapore Standard SS 586: 2008: Parts 1 – 3: Specification for hazard communication for hazardous chemicals and dangerous goods. All Singapore chemical manufacturers, suppliers and end users were required to implement GHS for single substance chemicals by the end of 2012, and to implement GHS for chemical mixtures by the middle of 2015.

The GHS is a United Nations’ (UN) developed system for chemical classification and hazard communication, through harmonised provisions for standardised labels and SDS. More than 65 countries have embarked on GHS implementation to date.Through the use of standard GHS hazard pictograms and a consistent GHS label and SDS format, miscommunication can be reduced leading to safer workplaces, not only locally, but also in countries participating in international chemical trade.

In Singapore, it is mandatory for each worker in the oil and petrochemical industry to receive industry customised safety training, including coverage on hazard communication, by completing the Oil and Petrochemical Safety Orientation Course (OPSOC) prior to starting work.

Personal protection

The use of PPE is another important aspect of a MHCP. PPE includes items of clothing such as overalls, gloves, boots and aprons, and equipment such as respirators, safety goggles and face shields.

In general, personal protection aims to protect workers from exposure to chemicals via the three main routes of entry into a person’s body: through the nose (inhalation), through the mouth (ingestion), and through the eyes or skin (direct contact).

As the use of PPE does not eliminate or reduce the hazard, the user is likely to be exposed to hazards if the PPE fails. Given that PPE is the last line of defence, a PPE programme is recommended to ensure that workers are protected when PPE is used. Key elements of a comprehensive PPE programme include PPE selection, fitting, PPE maintenance and storage, and user education and training.

On PPE selection, once the chemical hazard has been identified a useful approach is to consider the necessary PPE from ‘head to toe’. For protection against direct contact with chemicals, it is important that the material of the PPE is carefully selected for its ability to resist the chemical, particularly if it is toxic or corrosive. For full body protection, chemical protective suits are available depending on the hazard at hand, from level A offering the highest protection, down through to level D offering the least.

To ensure effective protection, PPE must be:

• Correctly fitted to its user
• Stored properly e.g. away from direct sunlight
• Subject to regular maintenance and checked before each use

It is also important for PPE to be replaced periodically depending on the frequency of use, permeability to the chemicals being handled and the lifespan of the material.As part of a comprehensive PPE programme, users will need to receive training on proper use and removal of PPE in order to prevent or minimise exposure to hazardous environments.

Emergency response

In the event of PPE failure or damage incurred during the course of work, emergency response is critical to mitigate the consequences of chemical exposure.

An Emergency Response Plan (ERP) is a backup to the control measures for the management of chemical hazards. Important ‘must haves’ in an ERP include implementation of measures for firefighting, spill control, evacuation, rescue, decontamination and first aid. The ERP should be formulated according to the hazards associated with the chemicals used and the nature of the operation. Emergency drills may be conducted regularly to verify the effectiveness of the ERP, allowing familiarisation with emergency procedures, and reinforcing the need to be prepared at all times.

For direct contact with a hazardous chemical, such as from a chemical splash on the skin or in the eyes, the provision of an onsite and easily accessible safety shower and emergency eyewash station is essential for immediate decontamination as part of first aid prior to medical treatment. As a rule of thumb, safety showers and emergency eyewash stations should be located so that they are accessible to an injured person within ten seconds along an unobstructed path.

Decontamination is carried out either by diluting the chemicals that are on the skin or in the eyes to a non-harmful level, or by irrigation, which involves flushing the chemicals out of the eyes or off the skin with potable water. Extra care must be taken to ensure that the water released from a safety shower and eyewash station is clean, and in particular, free from pipeline rust.This can be achieved by establishing a procedure for each station to be activated regularly; for example, flushing the water supply once a week and testing for proper operation for a few minutes each time. For chemical eye injuries, the use of aerated water is recommended as this would provide for a gentle scrubbing action to help remove contaminants more efficiently and safely.

Subsequent to onsite bodily decontamination, first aiders are advised to quickly identify the chemicals involved, obtain the SDS of the chemical, render first aid for the chemical exposure, and pass the SDS to the doctor or emergency medical staff for specific treatment.

Process safety versus personnel safety

While the aim of hazard communication, personal protection and emergency planning is to protect workers from harm, it is important to note that the emphasis of the above measures is on personnel safety. Personnel safety focuses on things that may cause injury or harm to an individual.

From a broader perspective it is equally important, if not more important, to look into matters pertaining to process safety.

Process safety focuses on the prevention of incidents involving leaks, spills, fires or explosions, by making sure that facilities are well designed, safely operated and properly maintained. Process safety is the result of a range of technical, management and operational systems working together to achieve the desired safety outcome.When the desired outcome is not achieved, a process safety incident occurs which may lead to worker injury.

To protect workers against the hazards posed by chemical substances, it is therefore also critical to pay attention to the management of process safety as this can help lower the probability of dangerous incidents.With fewer process safety incidents, the chance for workers coming into contact with a hazardous chemical will be reduced.

Case study

In this case study, liquefied propane – containing traces of hydrofluoric (HF) acid – was passed through a pressurised tank for treatment.The tank contained solid potassium hydroxide, which needed replacing as it had been consumed during the reaction.

During one such replacement a process technician isolated and depressurised the tank, after which he connected a rubber hose from the nitrogen gas supply valve to the utility connector valve of the tank, so as to initiate nitrogen purging.

Without confirming that the tank had been fully depressurised, he then opened the utility connector valve. The rubber hose burst, and the contents of the tank gushed out.The technician suffered chemical burns and later died from his injuries.

Causes and contributing factors:

• Opening the valves to depressurise the tank caused sludge to choke the bottom pipeline, hindering depressurisation
• The worker failed to ensure complete depressurisation of the tank
• The worker selected and wore a lower class HF suit
• Safe work procedures specifically for tank decommissioning were not available
• Management had no system in place to ensure that workers wore the appropriate PPE

Recommendations and learning points

Hazard communication:

• Deliver sufficient training in hazard communication and conduct safety briefings
• Install signage to remind workers of the hazards present
• Make the relevant SDS for each chemical easily available
• Develop a written safe work procedure specifying the correct PPE to be used

Personal protection:
• Provide workers with protective suits of the correct level of protection
• Superviseworkers,especiallythosenew to the job and those at risk of coming into contact with corrosive substances, to ensure proper use of PPE and familiarity with the safe work procedure

Emergency response:
• Install an emergency shower and eyewash station in the vicinity of the tank decommissioning operation, so that an injured worker may be able to access it within ten seconds of contact with the chemical

• Include the appropriate first aid treatment guidelines in the safe work procedure and make readily available the correct antidote for accidental skin contact with corrosive substances; for example, calcium gluconate gel for dermal exposure to HF acid

• Provide SDS to the doctor and/or medical professional attending to the worker exposed to the hazardous chemical so that the correct treatment can be promptly identified and administered

• Put in place appropriate spill control measures such as the use of secondary containment and availability of suitable absorbents for immediate response to chemical spillages

Process safety:
• Install a non-return valve on the tank utility connector line to prevent backflow of tank contents

• Ensure that flexible hoses are compatible with both the contents being conveyed and the system temperature and pressure. Equipment used for storing or handling corrosive substances, such as the flexible hoses and their couplings in this case, must be placed on a preventative maintenance and replacement programme to ensure they remain fit for use

• Replace weaker flexible hoses with stronger fixed piping where possible

• Document in the safe work procedure the importance of checking the tank pressure prior to connecting hoses for nitrogen purging operations

• Install suitable devices, such as pressure indicators and alarm/interlock systems, to facilitate onsite checks that the tank condition is safe before performing other works

• Conduct periodic risk assessment and safety reviews for high risk activities


For those encountering hazardous chemicals in the workplace, it is important to realise that protection from chemicals is more than just the use of personal protective equipment. Protection begins when an organisation decides if the use of chemicals is fundamentally necessary. If elimination or substitution of the chemical is not possible, then risk reduction can be achieved through the use of engineering and administrative control measures, with PPE used as the last line of defence.

For a comprehensive and holistic approach to protecting workers from chemical hazards, companies may consider the implementation of a Management of Hazardous Chemicals Programme (MHCP).Three aspects of a MHCP highlighted in this article are hazard communication, personal protection and emergency planning.

From a broader perspective, companies are advised to look into matters pertaining to process safety, as this can help lower the possibility of dangerous incidents involving chemicals.With fewer incidents, the chance of workers coming into contact with hazardous chemicals will be reduced.The prevention of process safety incidents is therefore key to protecting workers from unexpected contact with hazardous chemicals.

Published: 04th Jul 2013 in OSA Magazine


Edison J Loh

Edison J Loh, Senior Manager (WSH Practices)

About the WSH Council

The Workplace Safety and Health (WSH) Council was established on April 1, 2008, with one mission: to lead industry efforts in strengthening capabilities and building a progressive culture in WSH. The Council comprises leaders from the major industry sectors, the government, unions, and professionals from the legal, insurance and academic fields.

With a vision of a safe and healthy workplace for everyone, the Council works closely with the Ministry of Manpower and other government agencies, industry, unions and professional associations to develop strategies to raise WSH standards in Singapore, and to realise the national WSH 2018 strategy.

The Council’s main functions are to build industry capabilities to better manage WSH, promote safety and health at work, recognise companies with good WSH records and set acceptable WSH practises


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