(1)  If an injury is a disease which is of such a nature as to be contracted by a gradual process—

(a)  the injury shall, for the purposes of this Act, be deemed to have happened—

(i)  at the time of the worker’s death or incapacity, or

(ii)  if death or incapacity has not resulted from the injury—at the time the worker makes a claim for compensation with respect to the injury, and

(b)  compensation is payable by the employer who last employed the worker in employment to the nature of which the disease was due.

(2)  Any employers who, during the 12 months preceding a worker’s death or incapacity or the date of the claim (as the case requires), employed the worker in any employment to the nature of which the disease was due shall be liable to make to the employer by whom compensation is payable such contributions as, in default of agreement, may be determined by the Commission.

(2A)  The Commission is to determine the contributions that a particular employer is liable to make on the basis of the following formula, or on such other basis as the Commission considers just and equitable in the special circumstances of the case—

 
where—

C is the contribution to be calculated for the particular employer concerned.

T is the amount of compensation to which the employer is required to contribute.

A is the total period of employment of the worker with the employer during the 12 month period concerned, in employment to the nature of which the injury was due.

B is the total period of employment of the worker with all employers during the 12 month period concerned, in employment to the nature of which the injury was due.

(3)  Total or partial loss of sight which is of gradual onset shall for the purposes of subsection (1) be deemed to be a disease and to be of such nature as to be contracted by gradual process.

(4)  In this section, a reference to an injury includes a reference to a permanent impairment for which compensation is payable under Division 4 of Part 3.

(4A)  In this section, a reference to employment to the nature of which a disease was due includes a reference to employment the nature of which was a contributing factor to the disease.

(5)  This section does not apply to an injury to which section 17 applies.