This is ALL bullshit. 1.2 ppm of H2S is NOT harmful by any mechanism. Its one characteristic at the level is that it smells bad. Benzene is "slightly" carcinogenic. To develop the very rare cancer involved takes years-long exposure. And "methaline chloride" (correct spelling is "methylene chloride") is not found in oil at all. So if anyone says it is, they are lying in their eye teeth.
I have some methylene chloride. It is safe to use. I use it on occasion to ‘weld’ acrylic (Plexiglas). It welds by putting a thin film on each part into solution, then when the methylene chloride vaporizes the parts are ‘welded’ together - a very strong bond.