5.—(1) An authorisation–
(a)granted under regulation 4(1)(a), shall not so relax the provisions of Part II as to give rise to a risk to public health which the Secretary of State or, as the case may be, the local authority considers unacceptable;
(b)granted under regulation 4(1)(b) or (c), shall not relax the provisions of that Part so far as they relate to parameters mentioned in Table B or C or item 7 of Table D, or so as to give rise to a public health hazard;
(c)granted under regulation 4(1)(d), shall not relax the provisions of that Part so as to affect the fitness for human consumption of food or drink in its finished form.
(2) An authorisation shall specify the extent to which the prescribed concentration or value for any parameter is authorised to be contravened.
(3) An authorisation granted under regulation 4(1)(a) or (b) shall specify the date on which it ceases to have effect and an authorisation granted under regulation 4(1)(c) or (d) may specify such a date.