New ways for preservatives

COSSMA: Preservatives are designed to extend the shelf-life of cosmetic products and protect them from contamination. Have the tasks changed in recent years? 

Barbara Olioso¹: Preservatives’ function is indeed to make cosmetics microbiologically safe. Because most cosmetics are water based and with a long shelf life, they require a preservative system. Their task has not changed as such, however their safety evaluation has evolved over the years as the industry has grown and with it the exposure to preservatives.

For example, when parabens got restricted, many manufacturers switched to MI and MCI increasing their exposure and with that skin reactions. It was not intentional, it just happened and as soon as this became apparent the regulators restricted their use to rinse off only. Annex V is constantly reviewed in view of stringent safety; however, it is very unlikely new materials will be added to the list given the high costs – and the smaller the list gets, the higher the exposure. In my opinion the industry needs to work towards a more strategic approach based on Good Manufacturing Practise (GMP), packaging that minimises microbial contamination and keeping preservatives levels to a minimum, yet still complying with the regulations. Cosmetics safety is very much a balancing act between microbial safety and dermatological tolerance and the skin is still a great unfolding mystery which we are learning about as we go along.

Did the coronavirus pandemic affect the selection and development of cosmetic preservatives?

Even if there has been a great focus on hygiene and microbial safety controversial preservatives are still avoided by many consumers. If you do a Google trends search with a global setting for the last five years entering the keyword “paraben free” you will see that the trend is still growing. On top of this, many people have had skin reactions, possibly connected to the pandemic affecting the skin or the higher use of alcohol-based sanitisers, so I have seen mildness as a key criterion added to formulations briefs. This means paying extra attention in the selection of the preservative system and possibly avoiding fragrance.

In which types of packaging are preservatives particularly in demand?

Packaging can be a great ally to preservation by mini-mising the risk of contamination. However, there are cases, for example jars, where packaging is a great ally of contamination, so the preservative system has to work 
much harder to keep the product microbiologically safe, and the testing passing criteria needs to reflect the higher workload of the preservative system.

Are there other preservatives used here than, for example, with airless systems?

Packaging design is essential to minimise contamination and therefore the use of preservatives. However, an airless design might still allow contamination at the dispensing point, so depending on the type of airless you might still have potential for contamination. In my opinion, it is always important to check all the parameters affecting the product microbial safety, including, GMP and ingredients microbial quality. In fact, even with a well-designed airless container you still need to make sure the product is manufactured in hygienic conditions and that the ingredients used are not harbouring bacteria or moulds.

To what extent have the composition or also the raw materials of preservatives changed?

I have seen lots of blends of green chemistry multifunctionals, as the suppliers provide easy to use solutions to formulators. Some blends are preservatives blended with multifunctionals, some are broad spectrum and preservative free. There are also a lot of boosters coming to market.

What solutions can consumers with sensitive skin hope for?

In my opinion, people with sensitive skin are better off using fragrance free multifunctional products so that they expose their skin to less substances. It would be also good to watch out for dermatologically tested products on sensitive skin. It is not a guarantee they will not get issues, because every skin is different and changeable, but it helps to reduce their chances of a skin reaction.

“Free from preservatives” is a claim that many consumer feel safe about. What are the advantages and what are the risks?

The “free from” claim was born as a shortcut to avoid green wash as consumers do not have the technical knowledge to navigate the technical complexity of an INCI listing. The advantage of this claim is its simplicity for the consumers to navigate the marketplace and choose accordingly. However, the legal requirement for cosmetics to be safe still applies, so “preservative free” products still need to pass the relevant tests and safety evaluation to prove regulatory compliance and safety.

Many green brands have been doing this by using green chemistry multifunctionals, usually isolates or standardised materials with additional antimicrobial protection. They have a good track record and safety data coming from alternative sources, so toxicologists have approved formulations with preservative systems based on green chemistry multifunctionals for many years now.

What does “free from preservatives” mean for the manufacturer or formulator?

Formulators have to formulate in compliance with the Cosmetics Directive (Council Directive 76/768/EEC, European Union law) which define preservatives substances from Annex V. However, consumers level of trust towards these substances is low so formulators and brands have been left with the conundrum of formulating microbiologically safe products with consumers acceptance.

The solution has been using green chemistry multifunctionals with additional antimicrobial properties, either as a blend for full protection or in combination with preservatives to reduce their level of u

Since the environmental aspect is playing an increasingly important role, industry is more talking about refill systems. What are the challenges in terms of preservatives?

This is a great challenge. A major UK cosmetic products chain pioneered and tested this concept years ago with in store refills scheme but ended up abandoning it as it caused a few microbial issues. Now, with plastic pollution being such a great consumers concern, there have been many brands re-exploring this concept. I think the safest models are the ones like a return refill repeat scheme where the refill is taken care by the brand itself rather than the consumer.

In my opinion, this is the best model to apply the refill scheme safely. Pouches and in store refills are not ideal for the preservative system which might get overwhelmed if the reused container is contaminated.

What will be the greatest challenges in the development and use of preservatives in the future?

I believe green chemistry multifunctionals will become more common in preservative systems, the challenge will be the higher cost and the complexity associated with them. However, the more we use these materials the cheaper they will get and the more familiar we will become. Multifunctionals can also help keep preservatives exposure low and avoid high exposure scenarios we saw in the past, and also deliver additional skin or formulation benefits.

References

¹ Author of the Green Chemist’s handbook for cosmetic preservation, 2021