4.—(1) Subject to the following paragraphs, no person may use a dangerous substance or preparation in the treatment of wood.
(2) A dangerous substance or preparation to which paragraph (3) applies may be used—
(a)for wood treatment in industrial installations; and
(b)for in situ retreatment of wood for industrial or professional use by professionals covered by European Community legislation on the protection of workers.
(3) This paragraph applies to a dangerous substance or preparation which contains—
(i)benzo[a]pyrene at a concentration of less than 0.005 per cent by mass; and
(ii)water extractable phenols at a concentration of less than 3 per cent by mass.