Thursday, September 27, 2012

Incidents involving Hazardous Chemicals in Research Laboratories

26 Sep 2012

Recently, there were three serious laboratory incidents involving hazardous chemicals occurred in research laboratories of local institutes of higher learning (IHL) – one involved mixing of incompatible chemicals resulting in an explosion, another involved a highly flammable organic solvent causing a fire and the third was spillages of chemical from a ruptured container.

Explosion from Incompatible Chemical Reactions

The first case involved an explosion of a glass bottle containing chemical waste in a cargo lift of a laboratory building. There were two passengers in the lift when the accident happened. One of them, a research assistant, suffered from acid burns to his thighs, arms and eyes, and cuts from the shattered glass pieces. The other passenger, a senior research scientist, suffered from eyes and skin irritation. Investigation revealed that the research assistant had mixed unknown chemical wastes in one of the waste chemical bottles prior to transporting them to the basement storage room via the cargo lift. The incident was a result of incompatible chemicals being mixed causing pressure to build up in the bottle and resulting in an explosion.

Flash Fire from a Flammable Chemical
The second case involved a flash fire occurred in a science laboratory of an IHL. A research assistant suffered second degree burns on one of his hands and minor burns on his cheek. The incident occurred when the research assistant was in the midst of quenching the apparatus used for preparing a strong oxidising agent in a fume cupboard. The fire occurred when he was adding a highly flammable isopropyl alcohol (IPA) into the apparatus without cooling it in an ice bath. The incident was likely caused by the exothermic reaction between the oxidising agent and IPA which ignited the flammable vapour in the apparatus.

Chemical Spill from a Ruptured Waste Container
The third case involved a chemical spilt from a ruptured carboy in a clean room of a research institute. The chemicals were discharged from the wet scrubber system of a Metalorganic Chemical Vapor Deposition unit into 20L-carboys in preparation for the relocation of the unit. During the transfer of the filled carboys to the holding area by the waste collector, a breach in one of the carboys occurred, resulting in a spill and release of pungent gases. All staffs were evacuated and no person was injured . The incident was likely caused by the poor integrity of the carboy (due to wear and tear) and / or reaction of the chemicals (collected from the scrubber system) with the residual chemical in the carboy resulting in gas released in the carboy.

Other findings of the above cases include:

1) Inadequate labeling of chemical waste bottles
2) Insufficient training and supervision provided for persons carrying out the work
3) A risk assessment was not conducted before the start of the work
4) Safe work procedures were not implemented
5) Personal protective appliances were not worn during work

Recommendations*

Stakeholders performing similar work activity can undertake control measures such as the following to prevent a recurrence:

Risk assessment

1. Prior to work, conduct a proper risk assessment to identify all hazards and the risks involved. Control measures and safe work procedures must be established and implemented.

2. Safe work procedures and precautions have to be strictly adhered to when handling hazardous substances such as flammable or corrosive chemicals and oxidising agents.
Hazard communication and work practices

3. Ensure all chemical containers and waste bottles are properly labelled, stating clearly the identity of the content, hazards nature and precautionary measures whenever possible.

4. Incompatible chemicals like acid and strong oxidisers should not be mixed. Refer to the safety data sheets for any incompatible reactions.

5. Reusing of chemical containers should be avoided as far as possible. However, if containers are reused, they should be cleaned adequately before used to minimize contaminations and undesirable reactions.

6. Stakeholders should maintain good housekeeping in the laboratories. Workbenches and fume hoods should not be cluttered. Aisles and exits should be free from obstructions.


Training and Education

7. All persons involved in the work must be adequately trained and informed of the risks involved and the safety precautions to take.

8. All persons who are not involved in the work should not be allowed near areas where the work is carried out.
Personal protection and supervision.

9. Suitable personal protection equipment should be provided and worn at all time when performing the work.

10. Adequate supervision should be provided to ensure the work is carried out in a safe manner. Supervisors should be responsible to ensure safe work procedures are adhered to.
Engineering Control11. Fume hoods should be used when working with volatile chemicals or when airborne contaminants are generated. Guidelines on the proper usage of fume hoods should be developed and make available to all fume hoods users.
Figure 1: Photograph taken after flash fire in the fume hood.

Figure 2: Photograph of the ruptured carboy.

Useful Resources
1. Laboratory Safety Guidance, Occupational Safety and Health Administration (OSHA), please click HERE.
2. Laboratory Safety Chemical Fume Hoods, Occupational Safety and Health Administration(OSHA), please click HERE.

3. Workplace Safety and Health Act (Chapter 354A), please click
HERE.

4. Workplace Safety and Health (Risk Management) Regulations, please click
HERE.

5. WSH Guidelines on Management of Hazardous Chemicals Programme, please click
HERE.

6. School science laboratory safety regulations : for all primary and secondary schools, junior colleges and centralised institutes in Singapore / Science Unit, Curriculum Planning and Development Division, Ministry of Education.

Courtesy from WSH Council. For more info, pleas visit http://www.wshc.sg

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