Where the hazards and risks are very minor then it is sufficient to have considered them with no written assessment being required. For all other activities, and this includes use of VDUs, and most experimental work it is necessary to produce a written risk assessment. This should clearly identify the hazards to other people in the department or even the building as well as anyone immediately involved in the work or working nearby. The assessment must then determine any risks from the hazards and detail the steps which are to be taken to minimise, but ideally eliminate, the risks. The risk assessment can then simply state that the appropriate code of practice will be followed, but I would still recommend that a full risk assessment be carried out to ensure that the code of practice is still adequate.
Some staff get their students to perform the assessment.
This is a good idea as it makes them think about what they are doing, but it is still the academic supervisor who must sign the assessment and take responsibility for the consequences. Remember, in the event of an accident the first thing the Health and Safety Inspector will want to see is your risk assessment and any Code of Practice. If you can't produce them you may well find yourself in court. I do not jest, it has already happened elsewhere. Codes of paractice must be on display in the laboratories concerned.