In jurisdictions where written risk assessments are required for science practical activities, the general understanding is that the person performing the activity is the person responsible for the risk assessment. An example confirming this can be found in the Victorian DEECD documents on Chemical management found at http://www.education.vic.gov.au/school/teachers/management/Pages/chemica...
In particular, see section 6.4.1 in the Chemical Management Procedure: www.education.vic.gov.au/Documents/school/principals/management/chemical...
The requirement for written risk assessments and the technicality of who is deemed “responsible” to perform risk assessments can vary from jurisdictions (i.e., states and territories) and sectors (e.g., Government, Catholic, Independent). The principal of a school has the overall responsibility for the health and safety of people in their school and may delegate specific tasks to anyone in the school who has an appropriate level of competence to carry out the designated role.
In the Code of Practice on “How to manage the risks associated with hazardous chemicals in the workplace”, Section 3 'Assessing Risks' includes the topic 3.1: ‘Decide who should do the assessment'. This speaks of a collaborative approach, depending upon the expertise of the people involved. For complex cases, a number of people may need to be involved.
For example, sometimes a technician may have more knowledge of a chemical than the teacher or vice versa. In the classroom environment, the teacher knows the students in their class best and will need to assess the activity in view of their students' skills and behaviour.
Science ASSIST recommends that the person that has the best knowledge of the particular risks should carry out the risk assessment. Generally, in a classroom, this is the classroom teacher, while in a preparation room, this would be the science technician. However, there may be times when a collaborative approach is most appropriate.
Some other related documents include: