When informed by the occupational physician that a biological limit value has been exceeded, under the conditions set out in Article R. 4412-51-1, the employer:
1° Carries out a risk assessment in accordance with sub-section 2;
2° Implements the preventive measures and means provided for in Articles R. 4412-67 to R. 4412-73 ;
3° Carries out the checks on occupational exposure limit values provided for in sub-section 4;
4° Stops work at the workstations concerned until measures have been implemented to ensure the protection of workers.