We have covered a lot of ground on this topic and have discussed “gray areas” that require our personal judgment be exercised. Here is one more for you to consider.
More and more people expect that any “smell experience” that they might have encountered should be able to be reprised. We get into areas where simply identifying the chemistries that define the smell and then re-assembling them may not be prudent. A recent blog, seen here and not authored by me, addressed the smell of a rain storm and is a case in point. Many classes of compounds that are created when a rain storm arrives were categorized. All in all, thousands if not many, many times that number were bundled into three categories: ozone (and effects); petrichor (natural and not natural origin ingredients found on the ground and on pavement, etc.); and geosmin (mostly natural-origin materials deriving from flora and fauna directly or indirectly and associated with “dirt” = earth). However, the collateral chemisties that were not specifically identified are significant; many are known toxins. As we have addressed, toxicity is a function of dosage – i.e. “the dose makes the poison.” When we smell the smells of an arriving rainstorm we are problably smelling chemistries that are present in concentrations of parts per billion and even parts per trillion – extremely low but still great enough to create a personal “olfactory record” of a rain storm. And, at those levels they are probably not toxic; in more concentrated form they might be toxic; but, in liquefied form in a bottle they are probably too toxic to even be considered. So what are we to do?
One answer is to develop the best mimics that we can using safe ingredients to replace any odor-critical-but-too-toxic-to-use ingredients and to adjust and fine tune the composition until the odor experience is as close to real as possible. This is a tall task and very, very difficult. When we can get no closer we don’t forget to include all of the other sensory cues that we possibly can in order to “validate” the experience – if it is part of a video game adding thunder and lightning in generous proportions just may tip the balance.