If there was a real duty of care they would ensure that the police officers they employ are 'fit for purpose' - they would not be employing people physically unable to look after themselves. To short, too weak etc. to look after themselves so they need to supply CS gas and tasers to acheive basic defence ..... and then they whinge when that provision goes wrong and the crims get more injuries than a simple tustle would have created.
All their theorising and PC activities, often promoted by political motives, fails to cover the most basic of H&S considerations.