Anyone who has dropped something into a mucky river or pond... or even a pool of rainwater knows that you cannot reach into that without coming back with at least water on your hand, if not more. The same is true of reaching out to the Abyssal.. to Hell... or to any other realm or plane, really. In order to sense it.. you must send something out to do the sensing. And that bit brings something back with it. If you are not careful, what you bring back will build up, fester, and eventually manifest into something pyschological at first... physical later.

This can be shielded against partially if an intermediary is employed. An intermediary being something or someone of psychic potential who can handle the perception and who has a sufficiently skilled and powerful abilty to ride themselves of the residue. In the past, this is, I believe, the rationale behind sacrifices. Ie, the foretelling of future events through the examination of the innards or by the consumption of something vital of the sacrifice. There is a diminished or filtering effect... albeit it is not 100% effective since there is still contact and interaction with the sacrifice's physical remains and even applied mental sensing.

Unfortunately... there is no such thing as "gloves" or "personal protective equipment" for such activities. Eventually, you and your environment will become progressively saturated with the very elements you are examining.

One method to reduce the effective density of the contamination is through diffusion. Spread it out to as many recepticals as possible. This will effectively slow the progression, but not really stop the progression of potential symptoms.  For that, you need to be cleansed and properly.

Note, it is unethical to perform such a transfer without the recipeints' knowledge as excessive exposure and over time, this can lead to mental and emotional instability and even hallucinations.