Margin of Safety
The Margin of Safety is used when scientists want to make sure a chemical / ingredient is safe in products like cosmetics or food additives; they need to compare two important things:
1. The amount that caused no harmful effects in animal studies (called the NOAEL*)
2. The amount that people would actually be exposed to in real life (called the SED*)
They divide the safe animal study amount by the real-life exposure amount to get something called the “margin of safety.” This margin needs to be at least 100 to consider the chemical safe for use in products. Why 100?
Because scientists build in two important safety buffers:
First, they know that humans and animals can react differently to chemicals
Second, they know that different people (like children, elderly, or people with health conditions) may be more sensitive than others
To figure out the real-life exposure, scientists consider:
- How much of the product people typically use
- How strong the chemical is in the product
- How much gets absorbed into the body
- A person’s body weight
Think of it like having a 100-foot buffer zone between a playground and a busy road. The extra space helps ensure children’s safety, just like the margin of safety helps ensure chemical safety for everyone.
This is done for every individual ingredient.
Sometimes the NOAEL is not from an animal study but from information taken from use in the general population for example a foodstuff that is widely eaten by all members of the population, including children, elderly, or people with health conditions. In this case the buffer doesn’t need to be 100, and we use a margin of exposure (MOE) where the margin has to be greater than 1.
*NOAEL = No Observed Adverse Effect Level – the level at which no adverse effects were seen.
*SED = Systemic Exposure Dose – the level at which the body (internal / systemic) is exposed to by the ingredient in question.
I hope this provides some explanation of the calculations you see in the CPSRs provided by General Cosmetic Safety.