Given the task definition and input, reply with output. Given an abstract, indicate which of the provided candidate titles (Option1 and Option2) best describes it (respond with the text of the title, not option1/2).

Abstract: The impact of occlusion and the role of the counter ion on the permeation of nickel ions through skin have been examined using excised human skin. A highly sensitive electrochemical method was used to quantify the amount of nickel permeating the skin. The investigations show that nickel ions are capable of permeating the skin barrier when applied under occlusion. The process is slow, having a lag time of approximately 50 h. The permeation rate, and thus the physical amount being bioavailable, is considerably increased when aqueous nickel chloride is used in comparison with aqueous nickel sulphate. With respect to nickel permeation of the skin, we conclude that the choice of salt is an important consideration in patch testing.
Which is the apt title for the abstract? option1: Permeation of nickel salts through human skin in vitro. option2: The investigation of alleged insecticide toxicity: a case involving chlordane exposure, multiple sclerosis, and peripheral neuropathy.
Permeation of nickel salts through human skin in vitro.