I'm an avid smoker of Cannabis myself, i have a decade plus of experience of smoking. I've gone from smoking growers cash crops, to the lowest grade of quality, moving onto growing my own with putting next to no additives to the soil and it being a natural process.
Plant growth hormones used to regulate the growth of cultivated plants, weeds, and in vitro-grown plants and plant cells; these manmade compounds are called Plant Growth Regulators or PGRs for short. Some side effects from long term explosure can include,
Carcinogenicity--ability to produce cancer or to assist carcinogenic chemicals.
Mutagenicity--ability to cause genetic changes.
Teratogenicity--ability to cause birth defects.
Oncogenicity--ability to induce tumor growth (not necessarily cancers).
Liver damage--death of liver cells, jaundice (yellowing of the skin), fibrosis and cirrhosis.
Reproductive disorders--such as reduced sperm count, sterility, and miscarriage.
Nerve damage--including accumulative effects on cholinesterase depression associated with organophosphate insecticides.
Allergenic sensitization--development of allergies to pesticides or chemicals used in formulation of pesticides.
Here's an article for signs & symptoms of toxicity overload in the body
http://psep.cce.cornell.edu/Tutorials/core-tutorial/module09/index.aspx
Cannabis can find it hard to break down herbicide and pesticides meaning we end up smoking the molucule in the plant.
When it comes down to it, no one knows truly what is going into commercial or other peoples grows, i think this is a serious issue in today when weed is so hyped around legislation meditation etc,
Thanks for reading! Take care