Assessing the Environmental Safety of Cosmetic Ingredients


This page covers the below sections:

  1. What is Risk Assessment
  2. Predicting the environmental concentration
  3. Determining the risk
  4. Resources
  5. Practical Tips
  6. Prioritising Ingredients for Risk Assessment

  7. Case Studies – Refined Exposure Modelling

See the Contents for all available Sustainability Hub pages.

Safety is the number one priority of the cosmetics industry.  Safety doesn’t only mean human health, it also means ensuring that our products are safe for the environment after use.

From the brief developed by marketing, through the formulation process, to the use and disposal by the consumer, environmental fate matters.  The way that products are formulated and used determines what goes down the drain.  The individual properties of an ingredient in combination with its presence in the environment is the basis for estimating environmental risk.

What is Risk Assessment?

Hazard x Exposure = Risk

Hazard is a substance’s intrinsic potential to cause harm.  For example, taking a walk through the countryside and coming across a bull is a hazardous situation.  Naturally-occurring radioactive radon gas is a hazardous substance.  Chemicals used in everyday products and situations can also have hazardous properties.

However, hazardous substances do not necessarily pose a risk of harm.  The risk must be assessed by taking exposure into account.  For example, if the bull is in the next field behind a fence, it poses a very low risk.  Taking action to reduce exposure to radon significantly reduces the risk of adverse health effects.  Properly managing any hazardous properties of chemicals in terms of the way the chemical is used, where it ends up, and at what level is vital to ensure that the potential to cause harm does not translate into likelihood of causing harm.

Principles of Environmental Risk Assessment

The principles of environmental risk assessment involve data gathering, hazard identification, exposure estimates and finally, a comparison of environmental exposure to known safe levels.:

  • The chemical
  • The environment
  • The living organisms in the environment

The purpose of environmental risk assessment is to make sure that the concentration of the chemical in the environment is lower than the concentration which would have a negative effect on the environment and the life it supports.

How do cosmetic ingredients enter the environment?

Many cosmetic products are disposed down the drain after use.  Considerations are made as to whether the water is treated by wastewater treatments plants or directly into the aquatic environment.

Evaporation and release to air must also be considered for certain volatile products .

Predicting the environmental concentration

How can the concentration of a cosmetic ingredient in the environment be measured or predicted?  Different pieces of information are required which take into account the amount going down the drain and what happens to the ingredient in the environment; for example, whether it biodegrades, what happens to it in water treatment plants and which locations it travels to. 

  • Volume information – how much product is used and released by consumers?
  • The physchem properties of the ingredient - how it deposits between soil, sediment, water and the atmosphere.
  • An understanding of what happens to the ingredient in the environment – data from internationally standardised tests demonstrating that it biodegrades under appropriate conditions.
  • Specially developed computer models are available which take into account a large number of variables to estimate the environmental concentration of chemicals

Predicted environmental concentrations are usually used rather than actual measurements of how much of the chemical is in the environment.  A measurement only provides one snapshot in time whereas a prediction based on a model is cheaper and covers different scenarios, locations and conditions.  

Predicting the no-effect concentration

Ecotoxicity testing is used to understand the level of a substance in the environment which will not cause adverse effects for different species.

One of the fundamental ways in which environmental risk assessment differs from human health risk assessment is that in the environment, many more species are involved and the risk assessment is looking at protecting a population rather than an individual. 

Historically, in vivo tests were relied on to derive the predicted no effect concentration.  However, non-animal alternative tests are now available for many endpoints, and more are in development.

If it isn’t possible to derive a predicted no-effect concentration, the EcoTTC concept may be used.  TTC stands for Threshold of Toxicological Concern and it is a generic, very low concentration value based on historical data, below which there would be no appreciable ecotoxicity risk for the majority of chemicals.  There are different TTC values for cationic and non-cationic chemicals based on the different hazards presented by these two classes.

The TTC concept is intended to be used for screening purposes and rapid decision making and the ecoTTC has been developed specifically for the home and personal care sectors.  Further information can be found at Gutsell et al (2015).


Determining the risk

When information is available on the environmental concentration of an ingredient, and the concentration at which the substance will not cause harm in the environment, it is possible to determine the risk.  The risk is basically the ratio between the real-life environmental concentration and the concentration which is safe for the environment.

If this ratio is less than one, the substance is safe and the risk assessment is complete.

If this ratio is more than one, further investigations must be conducted, such as a refined risk assessment or an alternative ingredient.

Tiered approaches

Risk assessments often follow a ‘tiered approach’.  Level one, or the most basic tier, requires the least data and the least sophisticated methods, but is also the most conservative and could therefore overestimate the risk.  Higher tiers use more refined models and require a better quantity and quality of data, but the output will be more realistic.

If an ingredient fails a lower tier risk assessment, it is usually then assessed through a higher tier risk assessment using additional, more refined data.  This higher tier risk assessment will give a less conservative and more realistic result.

Example of considerations that might change in a tiered model for exposure assessment:


Practical Tips

  • A hazardous substance will not necessarily always pose an environmental risk.
  • It may be advisable to seek help from an external expert.
  • Running exposure modelling software requires a certain level of knowledge and understanding to be able to interpret the results and ensure accurate information is input into the model.
  • Ensure you have good quality, and sufficient, data on emissions, fate and ecotoxicology.
  • Exposure based high throughput screening method can maximize limited resources & large chemical data sets can be prioritized for further review. 

Prioritising Ingredients for Risk Assessment

Douziech et al (2019) suggest some tools for dealing with uncertainty in assessing the ecotoxicological impact of down-the-drain products.  The paper includes a case study, looking at the ecotoxicological impact of shampoo.  Part of the approach which was taken grouped together ingredients in shampoo products based on their function, in order to understand the relative contribution to the predicted environmental impact based on ingredient function. 

Therefore, this can be a possible approach to prioritising ingredients for environmental risk assessment, based on their function and therefore relative predicted environmental impact.

Douziech et al 2019

Another approach to prioritisation can be to conduct a high throughput screening of the ingredient portfolio, using a basic low tier risk assessment to estimate exposure and hazard; for example, using the ecoTTC approach to hazard.  Many chemicals will pass the most conservative risk assessment, and can be deprioritised for further work.  A smaller number of chemicals will require further, higher tier, assessment.

Gouin et al (2012) applied an environmental fate modelling tool as part of a prioritisation process for the environmental risk assessment of cosmetic ingredients used in China.

Example of prioritization approach to risk assessment using tiered risk assessments:


Case Studies – Refined Exposure Modelling

Price et al (2010) investigated how to improve emission estimates for home and personal care products by linking together EU population density data and country-specific usage data.  The paper estimates that the highest usage estimates for hypothetical regions are located in southern England and a transboundary area in Europe containing Belgium, the Netherlands, and Germany.

Examples of voluntary initiatives, case studies, innovations and technologies