You are so right, sensible engineers these days put on gloves for replenishments. In fact they use Nitrile or PVC gloves as latex gloves do NOT provide a barrier against organophosphates and mineral and synthetic oils for that matter. Also a certified activated charcoal canister breathin mask should be worn if the system to be replenished or inspected is hot when opened up to avoid breathin the vapours. When I started my apprenticeship in 1979 OH&S was all but non existant and the oil companies etc wre not forthcoming in telling what nasties were in their products and the associated health hazards. Mobil did not come clean that Jet Oil II had TCP in it until 1997, 43 years after it was developed and used. Another not to this is that most modern day herbicides and some pesticides are organophosphates and their effect is accumulative as it sits in the fat tissue and the body cannot break it down.