Propylene glycol intake limits and uncertainty factors
What it found
The authors propose raising the acceptable daily intake of propylene glycol from 25 to 62.5 mg per kg of body weight per day, for both children and adults.
This is based on a mode of action involving blood changes seen in toxicology studies and human data.
What they found
Animal and lab studies
Mode of action
The proposed mode of action involves an increase in serum propylene glycol concentrations after metabolic saturation. This leads to serum hyperosmolarity, which can ultimately cause hemolytic changes and red blood cell damage.
Studies in people and animals
Species similarities
Available toxicology studies and human data indicate species similarities in toxicodynamic response for this critical effect. This supports a chemical-specific adjustment factor of 1 for interspecies toxicodynamic differences.
Other findings
Current intake limit
The current acceptable daily intake for propylene glycol is 25 mg/kg bw-day. This applies a cumulative uncertainty factor of 100, with factors of 10 for both interspecies and intraspecies differences.
Exposure estimates
Some estimates of dietary exposure to propylene glycol approach or exceed the acceptable daily intake of 25 mg/kg bw-day.
Proposed new limit
The authors propose increasing the acceptable daily intake from 25 to 62.5 mg/kg bw-day. This would apply to both children and adults.
What the authors conclude
“Therefore, the species similarities in toxicodynamic response for this critical effect could support increasing the ADI from 25 to 62.5 mg/kg bw-day, applicable to both children and adults.”
Also in their conclusions
- They propose that the acceptable daily intake for propylene glycol could be increased from 25 to 62.5 mg/kg bw-day.
- They state that this new limit would be applicable to both children and adults.
- They suggest that species similarities in toxicodynamic response for this critical effect support reducing the total uncertainty factor from 100 to 40.
How it was done
Some estimates of dietary exposure to propylene glycol approach or exceed the current acceptable daily intake of 25 mg/kg bw-day. The authors wanted to see if a chemical-specific adjustment factor could replace the default uncertainty factor.
What it can’t tell you
- We summarised it from the abstract only.
- This paper does not present new experiments in people or animals. It is an analysis of existing toxicology studies and human data.
- The proposed higher intake limit is based on a mode of action that involves blood changes. It does not show what happens at the current or proposed intake levels in real life.
Who paid
- Conflicts
- Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Ari Lewis, Steven Boomhower and Charlotte Marsh are employed by Gradient, a private environmental consulting firm. Maia Jack is Chief Science and Regulatory Officer at the American Beverage Association. The work reported in this paper was conducted during the normal course of employment. This work was funded by the American Beverage Association and the International Organization of the Flavor Industry. The authors have the sole responsibility for the writing, content, and conclusions of this article.
- Authors work at
- Harvard University, USA
The paper
- Title
- Considerations for deriving a safe intake of propylene glycol
- Type
- Study
- Evidence
- Studies in people · animals · lab
- Summarised from
- Abstract only
- Cite
- Lewis AS, Boomhower SR, Marsh CM, Jack MM (2024). Considerations for deriving a safe intake of propylene glycol. Food and chemical toxicology. doi:10.1016/j.fct.2024.114460PubMed 38325632DOI
Summary written 26 Sep 2026. Check it against the paper before it changes what you eat. How we summarise papers · Report an error