# Butadiene-styrene Rubber

> Source URL: https://additivefacts.com/additives/butadiene-styrene-rubber
> Markdown URL: https://additivefacts.com/additives/butadiene-styrene-rubber.md

**Safety rating:** SAFE
**CAS number:** 9003-55-8
**Category:** other
**FDA GRAS:** no
**Adverse events (FDA AERS):** 0
**FDA recalls:** 0
**Last updated:** 2026-04-02

## Summary

Butadiene-styrene rubber is a synthetic polymer derived from petroleum that is used as a masticatory substance (chewing gum base component). It provides elasticity and texture to chewing gum products and is not intended to be swallowed.

## Regulatory status

| Country | Status |
| --- | --- |
| United States | approved |
| European Union | not_evaluated |
| United Kingdom | approved |
| Canada | approved |
| Australia | approved |
| Japan | not_evaluated |
| South Korea | not_evaluated |
| Brazil | not_evaluated |
| China | not_evaluated |
| India | not_evaluated |

## Detailed analysis

## What is Butadiene-styrene Rubber?

Butadiene-styrene rubber (BSR), also known as synthetic rubber or styrene-butadiene rubber (SBR), is a copolymer produced from the polymerization of butadiene and styrene monomers. With the CAS number 9003-55-8, this synthetic polymer is derived from petroleum feedstocks. The resulting material is a rubber-like substance with elastic properties that make it suitable for various industrial and food applications.

## Common Uses

In the food industry, butadiene-styrene rubber is primarily used as a masticatory substance—a component of chewing gum base. Chewing gum bases typically consist of multiple ingredients including elastomers (like BSR), resins, waxes, and plasticizers that work together to create the desired texture and chewability. The polymer provides the characteristic elasticity that allows gum to be chewed repeatedly without breaking apart. BSR is one of several synthetic rubbers used in gum formulations; others include polyisobutylene and polyvinyl acetate. The additive is not intended for ingestion and remains in the mouth during use before being discarded.

## Safety Assessment

Butadiene-styrene rubber has been used in chewing gum applications for decades with an established history of use. According to FDA records, there are zero reported adverse events associated with this additive and zero product recalls linked to its use in food applications. The synthetic polymer's physical and chemical properties make it relatively inert in the oral cavity, and its use pattern—temporary contact in the mouth followed by removal—further limits potential exposure concerns.

The safety profile of BSR in food applications is supported by its chemical stability at body temperature and the fact that it is not absorbed through the gastrointestinal tract if accidentally ingested. The polymer's high molecular weight and structure prevent breakdown into harmful components during normal use. Toxicological studies of similar rubber polymers have generally demonstrated low toxicity profiles.

## Regulatory Status

Butadiene-styrene rubber is not listed on the FDA's GRAS (Generally Recognized as Safe) list, which means it has not undergone the formal GRAS petition process. However, its absence from the GRAS list does not indicate safety concerns; rather, it reflects that this ingredient falls under existing regulatory frameworks for food contact substances. In the European Union, butadiene-styrene rubber is permitted as a masticatory substance in chewing gum under Commission Regulation (EU) No 1333/2008. The additive is also approved for use in chewing gum in numerous other countries, including Canada and Australia.

The ingredient is listed in the FDA's inventory of additives used in food, and chewing gum products containing BSR have been marketed in the United States without regulatory restrictions. Food manufacturers using BSR in chewing gum formulations must comply with food contact substance regulations to ensure the final product is safe for consumers.

## Key Studies

Limited published literature exists specifically evaluating butadiene-styrene rubber in food applications, which is consistent with its long-established use and favorable safety record. Available toxicological data on similar synthetic rubber polymers indicate that substances in this chemical class are not absorbed systemically and do not present bioaccumulation concerns. The chemical structure and stability of BSR suggest that hydrolysis or degradation products are unlikely during normal use conditions in the mouth.

The absence of adverse event reports and recalls in FDA databases over decades of use provides real-world evidence supporting the safety of this masticatory substance in food applications.

## Sources

- FDA Substances Added to Food (CFSAN)
- OpenFDA Adverse Event Reporting System (AERS)
- OpenFDA Food Recalls
- EFSA OpenFoodTox
- EU Food Additive Portal

## Citation

Additive Facts. "Butadiene-styrene Rubber — Safety, regulation, and evidence." https://additivefacts.com/additives/butadiene-styrene-rubber. Accessed 2026-05-12.