Cal. Health & Safety Code § 25400.16

(a) Property contaminated by methamphetamine laboratory activity is safe for human occupancy for purposes of this chapter only if the level of methamphetamine on an indoor surface is less than, or equal to, 1.5 micrograms per 100 square centimeters.
(b) Except as provided in subdivision (c), if property is contaminated by methamphetamine laboratory activity that included the use of lead or mercury compounds, in addition to the requirements of subdivision (a), property is safe for human occupancy for purposes of this chapter only if both of the following standards are met with regard to that property:
1. (1) The total level of lead is less than, or equal to, 20 micrograms per square foot.
2. (2) The level of mercury is less than, or equal to, 50 nanograms per cubic meter in air.
(c) Subdivisions (a) and (b) shall become inoperative on the effective date that a state or federal agency adopts a health-based target remediation standard for methamphetamine to determine when a property contaminated by methamphetamine laboratory activity only is safe for human occupancy, in which case any reference in this chapter to a human-occupancy methamphetamine standard specified in this section shall mean only the health-based target remediation standard for methamphetamine adopted by that state or federal agency.
(d) Property contaminated by fentanyl laboratory activity is safe for human occupancy for purposes of this chapter only if the level of fentanyl on an indoor surface is below the detection level.
(e) Subdivision (d) shall become inoperative on the effective date that a state or federal agency adopts a health-based target remediation standard for fentanyl to determine when a property contaminated by fentanyl laboratory activity only is safe for human occupancy, in which case any reference in this chapter to a human-occupancy fentanyl standard specified in this section shall mean only the health-based target remediation standard for fentanyl adopted by that state or federal agency.
(f) This section does not preclude a state or federal agency from adopting stricter health-based remediation standards than required under this section.