A chemical is a chemical regardless if it is naturally sourced or synthetic. A chemical itself isn't dangerous, it is the dosage. Your body Contains formaldehyde, arsenic, Mercury, aluminum etc. although the amounts are at a low enough dosage that it isn't toxic.
My point being that some organic growers I've come across make these claims about chemicals being bad all because they want to appeal to this nature fallacy.
Chemicals also affect reactions and phenomenon such as plant nutrient\mineral uptake. Synthetic fertilizers, especially of the hydroponic variety contain synthetic chelating agents. Most commonly EDTA or DTPA. These types of substances increase the availability of certain plant nutrients. They a high affinity for divalent cations, which can be released and absorbed by plants. EDTA itself is not well absorbed. So then the EDTA molecule goes looking for another cation to scavenge; e.g. calcium, magnesium or even lead and other heavy metals. The concentration of these within plant tissues at harvest very well could affect taste/aroma.
EDTA doesn't occur naturally whatsoever. If you knew much about chemistry you'd realize that these synthetic chelates
increase the uptake of heavy metals and minerals which can make Cannabis harsh, potentially affecting it's flavor and aroma. Not to mention that heavy metals are toxic to humans, and plants themselves. When an EDTA molecule goes scavenging for mineral cations it doesn't much care where they come from, and thus can rip them right out of a cell membrane/plant tissues. Hence potentially not great for the plant either.
BTW a more strict definition of a "chemical" is a
refined or
prepared substance. Some organic growers simply can't explain why such chemicals are 'bad', to what/whom and to what extent. EDTA is not a great chemical to have persisting in our environment because it affects [increases] the bioavailability of heavy metals in plants and other organisms. These synthetic chelates are employed to replace the role of natural chelating agents (such as humic, fulvic, amino acids) and the role of symbiotic microorganisms which benefit plants in nature. Then there are synthetic plant growth hormones and the potential or as yet unknown consequences of their consumption by people and plants; as well as their persistence in and affect on other organisms within the biosphere.
Then you have chemical (refined sources) of nitrates which can accumulate in soil and plants. These artificial sources of nitrate replace the roles of nitrogen-fixing and nitrifying bacteria. Nitrate is an anion and as such it is prone to leaching and contaminating ground water. N-fixing and nitrifying bacteria, on the other hand, are virtually incapable of producing "too much" nitrate for plants. However, when we apply chemical (refined) nitrates (as well as phosphates and ammonium) to soil they
can accumulate in plants as well as contaminate waterways leading to increased algae growth.
So what happens when plants with accumulated nitrates are consumed by animals? Here's what the Colorado agricultural extension service has to say about it:
Nitrates consumed by ruminants are normally reduced to ammonia, absorbed and excreted. Nitrite, an intermediate product is the culprit in nitrate poisoning. As some of the nitrate is absorbed into the blood it converts the blood hemoglobin to methemoglobin. The conversion of hemoglobin to methemoglobin reduces the oxygen carrying ability of the animal. The oxygen carrying capacity of the blood is severely reduced. Younger ruminants are more susceptible than older animals.
Interesting isn't it? If you honestly want to understand any of this, you have to realize it isn't even about "chemicals being chemicals" and that it matters more than you could know where exactly such chemicals come from. Natures chemists tend to know a thing or two about balance and how to keep it. To realize this you have to have some understanding of not only the fundamentals of chemistry, but biology and ecology as well. Most people aren't quite that interested in actually gaining such an understanding. I would kindly suggest such people quit thinking that they have the slightest clue what they are talking about.