ZOOL2030 Experimental & Physiological Zoology
Risk Assessment 2001
Activity Title: Cane Toad Osmoregulation
Location: Lab 307, Goddard Building, UQ St Lucia
Description: This practical is split into several different procedures, involving the use of
dissection and biological samples, physiological equipment, and a chemical diagnostic kit to test
for urea concentration.
1.
2.
3.
4.
5.
Dissection of Cane Toad and collection of blood and urine samples.
Measuring haematocrit percentage of blood.
Osmometry
Urea analysis
Electrolyte analysis
For procedures see attached Laboratory Manual – Laboratory 4
1. Dissection of Cane Toad and collection of blood and urine samples.
Students are given full instructions in how to handle the Cane Toads and are supervised closely
at all times. The position of the poison glands are demonstrated and students are given full
warnings about the toxicity of the skin, The wearing of laboratory coats, chemical goggles and
gloves is mandatory for staff and students during this procedure.
An instructional video of correct procedures for the toad dissection is shown to the students at
the beginning of the lab.
Pithing of the toads is carried out by an experienced tutor/laboratory technician wearing the PPE
as mentioned above. The toads are washed thoroughly to ensure that any toxin excreted as a
result of the pithing procedure is removed.
Students are supervised very carefully throughout the whole dissection procedure. An MSDS
obtained for Heparin (lithium salt) states that it is not classified as hazardous according to
Worksafe Australia criteria.
HAZARD – KINETIC & BIOLOGICAL
The main hazard associated with this procedure is a needle stick injury whilst collecting the
blood from the toad’s heart and possible contamination from the toads blood. Due to the
amount of supervision and instruction given, and that the heart is held using a pair of forceps
whilst being punctured, the likelihood of a needle stick injury from this procedure is improbable.
As there is no evidence to show that the Cane toad’s blood is toxic and that it carries any
communicable diseases, the severity of a needle stick injury would be noticeable/first aid
treatment only. As the students only carry out this procedure once under the conditions outlined
above, the risk is not significant.
Probability of injury – Improbable
Severity of Injury – Negligible
RISK – NOT SIGNIFICANT
HAZARD - BIOLOGICAL
Other risks would be biological hazards associated with the toad’s toxic skin.
The use of PPE, as mentioned above, would prevent the students coming in contact with the
toxin. All animal and contaminated pathological waste is disposed of immediately, and washing
facilities are available for the students.
Probability of injury – Improbable
Severity of Injury – Negligible
RISK – NOT SIGNIFICANT
HAZARD – MECHANICAL
A microfuge is used to spin the toad’s blood so that the plasma can be collected. The
centrifuge is in good working order, is situated away from where the students are working and is
operated by an experienced tutor.
Probability of injury – Improbable
Severity of Injury – MINOR
RISK – NOT SIGNIFICANT
2. Measuring haematocrit percentage of blood.
HAZARD – KINETIC & BIOLOGICAL
The risk here is a sharps injury from the haematocrit tube. The tube has to be pressed quite
firmly into plasticine to seal up one end and if pressed too firmly or at the wrong angle there is a
possibility that the tube would break. The biological hazard it toads blood in the tube might
contaminate any wound made by the broken tube. The students are instructed and supervised
very carefully over this procedure.
Probability of injury – Improbable
Severity of Injury – Negligible
RISK – NOT SIGNIFICANT
HAZARD – MECHANICAL
A haematocrit centrifuge is used to spin the blood in the tubes down. The centrifuge is in good
working order, is situated away from where the students are working and is operated by an
experienced tutor.
Probability of injury – Improbable
Severity of Injury – Minor
RISK – NOT SIGNIFICANT
3. Osmometry
The students measure the osmotic pressure of the plasma and urine using a vapour pressure
and/or freezing osmometer. Both pieces of equipment are in good working order and there are
no associated hazards.
4. Urea analysis
The students measure the urea concentration of the plasma and urine using a Sigma Urea
Nitrogen Diagnostic kit.
HAZARD – CHEMICAL
Although some of the chemicals listed are classified as hazardous, the combination of control
measures used and the fact that they are in very dilute concentrations means that the risk is not
significant.
See attached chemical substances risk assessment and MSDS’s
HAZARD – THERMAL
The samples need to be boiled in a water bath for 10 minutes. It is quite possible to get water
and steam burns whilst handling the tubes in and out of the bath. This process is carried out by
an experienced tutor, who uses elbow length heat proof gloves and long tongs. Extreme
caution is used when opening the lid of the water bath to prevent steam burns, and warning
signs have been put on the bath cautioning staff and students about the hazard.
Probability of injury – Remote
Severity of Injury – Major
RISK – LOW
5. Electrolyte analysis
The students Sodium and Potassium Ions using a Flamephotometer. This piece of equipment is
in good working order, the gas cylinder is chained upright to the bench and the regulator has
been checked and tagged. No Hazards are associated with this procedure.
Chloride ions are also measured using a Chloride titrator.
HAZARD – CHEMICAL
Although the chemicals listed in the supporting electrolyte are classified as hazardous, the
combination of control measures used and the fact that they are in very dilute concentrations
means that the risk is not significant. The electrolyte is contain within the titrator and the
students have no contact with it at all. Occasionally the tutor will have to change the solution for
fresh stock.
See attached chemical substances risk assessment and MSDS’s