As used in this subchapter:
(1) “Environmental law” means any federal, state, or local law, rule, regulation, or ordinance relating to protection of the environment or human health;
(2) “Estate” means the estate of the decedent if by reference thereto a provision has been made applicable to the executor or executors of a will and means the trust estate if by reference thereto a provision has been made applicable to the trustee or trustees of such an estate;
(3) “Fiduciary”, and the masculine singular form of the pronoun referring to the fiduciary, means the one (1) or more executors, whether male, female, or corporate, of the estate of a decedent, or the one (1) or more trustees, whether male, female, or corporate, of a testamentary or inter vivos trust estate, whichever in a particular case shall be appropriate; and
(4) “Hazardous substance” means any substance defined as hazardous or toxic or otherwise regulated by any environmental law.