Ingredients that may contain, release, or break down into formaldehyde: 2-bromo-2-nitropropane-1, 3-diol, Bronopol, Diazolidinyl urea, DMDM hydrantoin, Imidazolidinyl urea, Quaternium-7, 15, 31, 60, etc. This list is far from comprehensive because of the various ingredients that can break down to form contaminants, and the various use of scientific names--many ingredients go by different names or alphanumerals. As well, the "natural" ingredient may be on the bottle (e.g., "coconut oil") but it may have been chemically altered to produce the needed ingredient. Do not be deceived by the use of the unscientific terms "non-toxic" or "from natural ingredients" Some of the various names: Mineral oil--paraffin, paraffin oil, paraffinum liquidum Formaldehyde--Quaternium-15, DMDM hydanoin, MDM hydantoin, Methanal Urea-Imidazolidinyl urea (Germal 11), Diazolidinyl urea (Germal 115) BNPD-2-bromo-2-nitropropane-1,3-diol (or Bronopol) FD&C Blue No. 1--(Cl 42090) FD&C Green No. 3-- FD&C Yellow No. 5--(Cl 19140) FD&C Yellow No. 6--(Cl 15985) FD&C Red No. 33--(Cl 17200) DEA--Diethanolamine TEA--Triethanolamine (also listed occasionally as "Tea") Sodium laureth sulfate--Sodium lauryl ether sulfate Padimate-0--Octyl dimethyl PABA Kathon GC--Methylisothiazolinone, methylchloroisothiazolinone BHA--Butylated hydroxyanisole Fluoride--Sodium monofluorophosphate, sodium fluoride IN ADDITION, to make it EVEN more complicated, SOME of these ingredients are fine, if the product has been appropriately processed--ie. PEG; Polyethylene; Polyethylene Glycol; Polyoxyethylene; "-eth"ingredients; Oxynol; Polysorbate 60; Polysorbate 80 may create 1,4 dioxane; however, if the product has been vacuum stripped, it is safe (most companies do NOT vacuum strip, it is very costly). AND 2-bromo-2-nitropropane-1, 3-diol, Bronopol, Diazolidinyl urea, DMDM hydrantoin, Imidazolidinyl urea, Quaternium-7, 15, 31, 60, may break down into, or be contaminated with formaldehyde. However, this can be avoided in the processing as well. If your products contain any of these ingredients, make sure the products themselves have been tested by a 3rd party to ascertain that there are NO contaminants. Don't try to become your own scientist, unless you have adequate scientific background....just make sure you buy from a company who has had their products (not their ingredients) tested by 3rd party scientists. For products without any of the above chemicals