Administrative Control (AC) Levels for chemical substances are occupational standards with legal binding. They are established and updated by a national expert meeting convened ad hoc when deemed necessary by the Japanese Ministry of Health, Labour and Welfare in response to new scientific knowledge.
As a general rule, the expert meeting organised by the Ministry discusses:
It then determines values of its own.
Takahashi, K. and Higashi, T: The development and regulation of occupational exposure limits in Japan. Regul Toxicol Pharmacol 46 (2006), pp 120-125
Sakurai H: Brief introduction to occupational exposure limits in Japan. J Occup Health 39 (1997), pp 246-260