Electrical safety hazard: vortex mixer

This hazard alert is a warning to all operators of vortex mixers and other aged, small laboratory electrical appliances.

Incident

An electronics technician was conducting electrical testing of laboratory appliances and discovered that a vortex mixer had burnt out its earth circuit during the test process. The vortex mixer was an earthed appliance and this requires any touchable metal surface of the appliance to be safely earthed.

The vortex mixer was found to have wiring that didn't conform to Australian Standards because the appliance's earth wire was connected to the appliance body via a conducting track on the internal printed circuit board (PCB). A PCB track is not capable of carrying the high amperage current in a fault situation, would burn out, and would leave the casing of the appliance live.

Preventive Measures

It is important that all small laboratory electrical appliances be treated as portable appliances for the purposes of the University's Electrical Safety Procedure and be electrically tested annually. This is particularly so with aged appliances because, as has been documented in other hazard alerts (OHS-Hazard Alerts index), the design standards of appliances with respect to electrical safety have improved significantly over the past decade.

All untested vortex mixers should be taken out of service, switched off and unplugged, and Budget Unit management notified. Testing, in accordance with ANU electrical safety policy, should be organised and successfully completed before the appliance is brought back into service.

For further information email: OHS Officer

Injury from changing a cracked glass pipette on a vacuum device

Cuts / puncture wounds in laboratories are hazardous not only from the damage caused to the body, but also due to their potential to transfer toxic, infectious or genetically manipulated material through the broken skin into the body. Broken skin can carry a high risk of biological infection.

Hand manipulation of fragile glass objects, for example Pasteur pipettes, can exacerbate the risks from this issue, and where possible should be replaced by fracture resistant plastics.

A technician was injured while trying to disconnect a cracked glass pipette from a piece of rubber tubing. The glass of the cracked pipette crushed between the technicians fingers and caused cuts to the finger and thumb through a glove. This caused a potential exposure through the skin barrier to bacteria and other products that had been sucked through the glass pipette.

The use of glass and sharps in a PC2 / microbiological / GM laboratory should be avoided wherever possible. In this situation the glass pipette can be easily substituted with a plastic pipette that will perform the same function.

Laboratory managers should look at their laboratory procedures where glass pipettes are involved, and assess whether it is practical to change to plastic pipettes.

For further information email: OHS Officer

Danger from ignition sources in laboratories/workshops - mobile phones

A research or teaching laboratory has many potential health and safety hazards. Some of these are obvious and some not so. Ignition sources are a potential concern when flammable liquids or gases are used or stored in a laboratory or workshop. It only requires a fuel source, ignition source and air to create a potential fire or explosion with devastating results.

Common sources of ignition include

• Flames, such as from Bunsen burners, loop flamers, glass sealing torches, gas welding
• Electrical equipment with sparking components (motor, thermostats, relays, switches etc)
• Very hot surfaces (which can cause ignition when hotter than a substances auto ignition point. For example; oven elements, hot plates, radio frequency coils)

Equipment in the laboratory should ideally be intrinsically safe (i.e. they do have any of the sources of ignition indicated above). Additional information can be found in Australian Standard 2381, electrical equipment for explosive atmospheres, or the Workshop or Flammable liquid safety course notes

It should be notes that personal mobile phones may act as a source of ignition, as they are not intrinsically safe. Mobile phones should therefore not be kept on personnel or in the hazardous areas of laboratories, workshops, chemical storerooms or other places flammable gases or liquids may be stored or used.

For further information email: OHS Officer

Electric shock from changing a fuse in an electrical appliance

A technician received an electric shock recently when removing a main power fuse from an electrical appliance in a research laboratory in The Faculties. The fuse holder cap did not extract the fuse (as it should have done), the fuse had not blown, the power to the appliance was on, and the electric shock occurred when the technician touched the in situ exposed fuse.

The following standard practices should always be in place when such a task is undertaken:

• the appliance is unplugged from the electricity supply before attempting to change a fuse,
• if a fuse holder cap is found to have lost its fuse-retaining function, then the fuse holder is replaced.

It should be noted that the University's Electrical Safety Procedure requires that persons working on electrical appliances must be approved to do so by the responsible Budget Unit and such persons must have completed the University's Electrical Safety course.

For further information email: OHS Officer

Needle-stick awareness: collection, first aid, notification

Needle / Syringe found On Campus

If a needle/syringe is discovered on campus, phone Security, 6125 2249 (ext 52249 on internal phone system). Security staff are trained in safe needle collection procedures, have the equipment to collect and dispose of the needle, and will do so as a high priority.

Needle-stick Injury

If a needle-stick occurs, the following first aid is recommended:

• encourage the wound to bleed by squeezing gently,
• wash the affected area with water if available,
• cover the wound, with a band-aid if available,
• ESSENTIAL: go to University Health Service, or your doctor, or a hospital as soon as possible,
• have the location of the needle/syringe reported to University Security [phone 6125 2249 (ext 52249 on internal phone system)] for safe pick-up,
• report the incident to your supervisor.

University Health Service

The University Health Service (North Rd, building 18, phone 6125 3598) provides the currently defined medical services for a potential needle-stick injury, including vaccination for tetanus / hepatitis A / hepatitis B; blood sampling for pathology evaluation; and safe storage of the needle prior to subsequent disposal.

Notification of a needle-stick injury

For every injury, exposure or dangerous occurrence that occurs, supervisors must ensure that the web-based OHS Incident Notification form is completed and submitted to the OHS Unit as soon as possible.

For further information email: OHS Officer

Self-indicating (blue) Silica Gel

Self-indicating (blue) silica gel has been a common desiccant in laboratories for many years. The indicator is cobalt (II) chloride, present in a concentration of 0.5 to 1% weight for weight on the amorphous silica gel. The moisture sensitive material changes from blue to pink as it absorbs moisture. Heating can regenerate the desiccant.

The common laboratory routes of exposure to self-indicating (blue) silica gel are via contact with the skin and inhalation of dust. The material is generally granular since it is makes a better desiccant. Dust can be created from the desiccant by crushing, abrasion, rubbing or otherwise powdering the material. It is the cobalt (II) chloride in the desiccant that is of a health concern.

The dust is capable of drying the skin and may cause irritation and dermatitis. Allergic inflammation may occur following exposure to cobalt, usually exhibited as red patches. If contact occurs to un-gloved hands, wash with soap and water. A moisturising cream may be of benefit to re-hydrate the skin.

Inhalation of the dust is slightly discomforting/irritating to the upper respiratory tract. Inhalation of dust may aggravate a pre-existing respiratory condition (asthma, emphysema, bronchitis etc). Respiratory sensitisation may result in allergic/asthma like responses; from coughing and minor breathing difficulties to bronchitis with wheezing and chest tightness. Cobalt (II) chloride has been revealed to be a confirmed animal carcinogen at relatively high doses. A European Commission Directive (98/98/EC) reclassified cobalt chloride as a potential carcinogen by inhalation. The International Agency for Research on Cancer (IARC) indicates there is limited evidence for carcinogenicity of cobalt (II) chloride in experimental animals, and has assigned cobalt and cobalt compounds as possibly carcinogenic to humans (group 2B).

It needs to be remembered that the EC directive was for the pure chemical, whereas the silica gel contains 1% w/w and is within the gel material. The health risk associated with self-indicating (blue) silica gel therefore only exists when handling the material and exposure to the dust.

It is recommended that -

• Alternative to the self-indicating (blue) silica gel are available and should be purchased/used when possible. An appropriate replacement desiccant is the self-indicating (orange) silica gel available from most laboratory chemical suppliers.
• Self-indicating (blue) silica gel should be handled in the fume cupboard whenever there is a risk of generating dust. For example, pouring into desiccator jars, heating vessels. The risk of exposure to a small dust cloud that may result when a desiccant jar is opened is considered insignificant. If there are concerns regarding the desiccant or chemicals in the jar, the jar should be opened in the fume cupboard.
• Dusty self-indicating (blue) silica gel should be gradually removed from service. Material should be placed in a tough plastic bag and sealed. Disposable is via the appropriate waste contractor.
• Material should not be powdered/crushed or handled in any way likely to cause significant dust exposure.

For further information email: OHS Officer

Reference:

1. CHEMWATCH Material Safety Data Sheets - Cobalt (II) chloride and self-indicating (blue) silica gel.
2. Various commercial web sites related to silica gel.
3. IARC agents and summary evaluations