(a) The following shall constitute employers who shall be subject to the provisions of this chapter:
(1) Every person, partnership firm, association, trust, profit or nonprofit organization, corporation or legal representatives thereof, that has one or more employees in this State and is engaged in activities which involve the use or presence of ionizing radiation. Provided, however, that any employer who employs less than three employees may, at his option, elect not to be subject to the provisions of this chapter.
(2) The State, or any agency thereof, and each political subdivision of the State, or any agency thereof, or public or quasipublic corporation that has one or more employees and is engaged in activities which involve the use or presence of ionizing radiation.
(b) The following shall constitute employees who shall be subject to the provisions of this chapter:
(1) Every person, including a minor, whether lawfully or unlawfully employed, in the service of an employer subject to this chapter under any contract of hire or apprenticeship, express or implied, and all helpers and assistants of employees whether paid by the employer or employee, if employed with the knowledge, actual or constructive, of the employer.
(2) Every person performing service in the course of the trade, business, profession or occupation of an employer at the time of injury or disability, provided such person in relation to this service does not maintain a separate business, does not hold himself out to and render service to the public and is not himself an employer subject to this chapter.