Indiana Code Title 22. Labor and Safety § 22-3-7-33

Sec. 33. (a) An employee shall be conclusively deemed to have been exposed to the hazards of an occupational disease when for any length of time, however short, he is employed in an occupation or process in which the hazard of the disease exists.  The employer liable for the compensation provided for in this chapter shall be the employer in whose employment the employee was last exposed to the hazards of the occupational disease claimed upon regardless of the length of time of the last exposure.  In cases involving silicosis or asbestos, the only employer liable shall be the last employer in whose employment the employee was last exposed during the period of sixty (60) days or more to the hazard of the occupational disease.  In cases involving silicosis or asbestos, an exposure during a period of less than sixty (60) days shall not be considered a last exposure.  The insurance carrier liable shall be the carrier whose policy was in effect covering the employer liable on the last day of the exposure rendering the employer liable, in accordance with the provisions of this chapter.

(b) Whenever any employee for whose disability or death compensation is payable under this chapter shall, at the time of the last exposure, be exposed in the joint service of two (2) or more employers subject to the compensation provisions of this chapter, the employers shall contribute to the payment of the compensation in proportion to their wage liability to the employees.  Nothing in this section shall prevent any reasonable arrangements between employers for a different distribution between themselves of the ultimate burden of compensation.