Odd or Bad Odors Developing from Cosmetics

I keep getting email inquiries regarding this topic, I have replied to on Twitter as well because of their frequency.

Here are my Tweets today on the matter, expanded for this post.

Email reply: Odd odor cosmetics There is no reason a cosmetic should begin to smell odd except if it is going or has gone off, regardless of the expiry claims.

Cosmetic preservatives are supposed to accommodate consumer use, temperature fluctuations, and more. Cosmetics that contain water or infusions can go bad.

An odd or bad odor of any cosmetic can be the last sign something is wrong. Tossing it out is best, or a refund, or get a free replacement.

"When Should I Throw Out a Product?"
http://www.paulaschoice.com/expert-advice/skin-care-basics/_/when-should-i-throw-out-a-product
"And remember: If it smells funky, looks gunky or the texture has changed significantly—definitely toss it out!"

Within a reasonable time reputable cosmetic companies do not excuse, or refuse refunds, or free replacements over such matters.

I have had food well kept go off before a best before expiry date too. I have never had a problem getting a refund, or free replacement. The product was unstable.

2011 "Effective vs. Ineffective Preservation Using Water Activity*"
http://www.cosmeticsandtoiletries.com/formulating/function/preservatives/112901129.html?page=6#.Ur8a-7aiJa4.twitter
"This illustrates the need need to concentrate on controlling and preventing microbial contamination during manufacturing."

The point is that you should be able to count on a cosmetic not to go off well before keeping it too long becomes a hazard.ttp://www.

2013
"Challenges Persist in Working with Green Materials in Beauty Product Development"
http://www.gcimagazine.com/business/rd/ingredients/Challenges-Persist-in-Working-with-Green-Materials-in-Beauty-Product-Development-225967991.html#.Ur8zdyCPq_8.twitter
"Stability also is a major issue, with some green preservative systems leading to discoloration and/or odor changes."

2013
"The preservative wars"
http://www.aocs.org/Membership/FreeCover.cfm?itemnumber=18591
“No single preservative is equally effective against all types of microorganisms” ... Although synthetic preservatives bear the brunt of criticism from anti-preservative groups, natural preservatives are not free from controversy." 

The topic of "all natural" cosmetics and the preservation of cosmetics is not a simple one. What side of the preservative wars am I on? Cosmetics must be safe to use. I am on the side of reputable evidence-based information with history.

Email Reply: Why did I say with history? From http://www.aocs.org/Membership/FreeCover.cfm?itemnumber=18591
See the paragraph starting with "While consumers tend to view" and the one after it under "Going natural has its own challenges" To be clear, I side with the first of the two paragraphs.

Peer-reviewed evidence-based science is used to re-evaluate cosmetic ingredients and levels used in cosmetics as needed, with continuing research.

Note: the 2nd paragraph "some studies have reported adverse effects of natural preservatives, including allergic reactions, early puberty, and cancer".

Ongoing reputable scientific research "in context" is very important!

The 2nd paragraph comments make no sense to me without reputable, peer-reviewed, scientific evidence to support them. And by those same comments,
"The data haven’t been presented to scientific committees and papers haven’t been published"