; and (3) by adding at the end the following new paragraph: (9) provides that in determining whether a violation is repeated, the State shall consider the employer’s violations within the State, in conjunction with the employer’s history of violations under other States’ occupational safety and health plans approved by the Secretary and the employer’s history of violations in those States where the Secretary has jurisdiction under this Act, in a manner that is at least as effective as provided under section 17. . V National Institute for Occupational Safety and Health 501. Health hazard evaluations by the National Institute for Occupational Safety and Health Section 20(a)(6) ( 29 U.S.C. 669(a)(6) ) is amended by striking the second sentence and inserting the following: The Secretary shall determine following a written request by any employer, authorized representative of current or former employees, physician, other Federal agency, or State or local health department, specifying with reasonable particularity the grounds on which the request is made, whether any substance normally found in the place of employment has potentially toxic effects in such concentrations as used or found, or whether any physical agents, equipment, or working condition found or used has potentially hazardous effects. The Secretary shall submit such determination both to employers and affected employees as soon as possible. . VI Effective date 601. Effective date (a) General Rule Except as provided for in subsection (b), this Act and the amendments made by this Act shall take effect not later than 90 days after the date of the enactment of this Act. (b) Exception for States and political subdivisions The following are exceptions to the effective date described in subsection (a): (1) A State that has a State plan approved under section 18 of the Occupational Safety and Health Act of 1970 ( 29 U.S.C. 667 ) shall amend its State plan to conform with the requirements of this Act and the amendments made by this Act not later than 12 months