The following is a summary of the latest safety analysis of butylene glycol:

March 2005

Current Safety Assessments of Butylene Glycol

Butylene glycol (BG) (1,3-Butanediol, CAS No. 107-88-0) is a common humectant and solubilizer used in cosmetic and food preparations. Its safety and usage has been well documented and approved by such agencies as the US FDA, the US EPA, and the CTFA (see below). Studies have even shown that when ingested by mammals, BG metabolizes into b-hydroxybutyraldehyde which is then converted through a process of intermediates into acetyl CoA, an intermediate of the citric acid cycle, which supplies energy to the body in the form of ATP.[1]

The following statements come from the United States Environmental Protection Agency High Production Volume Challenge Program Submission 2003: "Acute toxicity is minimal by the oral and inhalation routes, and repeated-dose administration of high doses to experimental animals and humans does not produce adverse effects until the amount ingested becomes a significant contributor to the individual’s caloric requirement. Even then, the observed effects are limited to minor reduction in body weight gains…resulting from the metabolism of 1,3-Butanediol as a nutrient."1 The EPA reviewed this statement and found that "Adequate data were provided for the acute, repeated-dose, and developmental toxicity endpoints for the purposes of the HPV Challenge Program." The data of this study also showed that BG had no multigenerational nor developmental toxicity. It also showed that chronic studies did not show any carcinogenic activity.

The US FDA has also verified the safety of BG even as an ingestible. The FDA approved BG as a direct food additive as a flavor solubilizer. It has also been granted several indirect additive approvals.[2]

The use of butylene glycol in cosmetics has been reviewed by the Cosmetic Ingredient Review of the Cosmetic, Toiletry and Fragrance Association (CTFA). That report concluded that BG was safe as presently used in cosmetics.[3]

[1] www.epa.gov

[2] www.fda.gov; Federal Register, Vol. 62, No. 92, May 13, 1997; Part 172.

[3] Cosmetic Ingredient Review. Final Report on the Safety Assessment of Butylene Glycol, Hexylene Glycol, Ethoxydiglycol, and Dipropylene Glycol. J. Am. Coll. Toxicol. 5:223-248.

Butylene glycol is the safest of a class of chemicals called solubilizers

Butylene Glycol:

Background: Glycol’s have extremely wide variations in toxicity that match their many applications in a variety of consumer products. Ethylene glycol is very well known as automobile anti-freeze. It is toxic upon ingestion, causing direct toxicity to erythrocytes [red blood cells]. Ethylene glycol is also teratogenic and a possible bone marrow depressant. The very similar propylene glycol has none of the same toxicity associated with ethylene glycol. In huge oral doses, propylene glycol can cause liver and kidney toxicity... Propylene glycol is both a skin irritant and a sensitizer.

Butylene glycol (1,4-butanediol) has none of the above toxicities. In fact there has been no documented organ-specific toxicity associated with 1,3-butanediol. Butanediol is also not a carcinogen.2 It is not a skin sensitizer, and is not considered a skin irritant.1 In undiluted form butylene glycol may irritate the eye and lining of the respiratory tract.

Some Consumer Advocates call butylene glycol an anti-freeze, and imply it is toxic because of its characterization as a glycol. Just about anything added to water is an anti-freeze. It is ludicrous then to label all anti-freeze formulations as toxic. Glycol’s can prevent water from freezing at 0 degrees Celsius. This fact does not make all glycol’s toxic, especially in the same manner and at the same levels of toxicity. Butylene glycol is present in several Neways products.

Safety concerns: Butylene glycol is rapidly absorbed through any tissue, including the skin. It is rapidly metabolized to gamma-hydroxybutyric acid in animals and humans. Gamma-hydroxybutyric acid is a naturally occurring chemical found in the brain and peripheral tissues of humans. Gamma-hydroxybutyric acid is also rapidly metabolized into succinate through the tricarboxylic acid cycle within the body. Given in high doses, a neuromodulator effect can be seen.4 However, in the small doses used as a solvent in pharmaceuticals and nutritionals, there are no known side effects. In water-based products, a concentration of 0.5% butylene glycol, as a solvent, would be safe for topical use.

Safety profile: Butylene glycol in concentrations of 0.5% or less in a topically applied product scores at least 9 out of 10, with a score of 10 being perfectly safe.

Funk JO, et al. Contact Dermatitis 1994;31:236-41. Propylene glycol dermatitis: re-evaluation of an old problem.

Irwin RD. National Toxicology Program, Toxicity Report Series no.54, NIH, US Dept of Health and Human Services, NIH Publication #96-3932, 41 pages, 80 references.

BASF Technical Data Sheet. 1997 Jan. http://www.basf.com

NTIS Publication #PB97-108161. 1996 May. http://ntp-server.niehs.nih.gov/htdocs/ST-studies/TOX054.html

Anon. J Am Coll Toxicol 1985;4(5):223-48. Final report on the safety assessment of butylene glycol.

When comparing small dialcohol (glycol) molecules, molecular weight makes a huge difference in effect and toxicity. Butylene glycol is a better humectant (skin moisturizer) and less toxic than propylene glycol. As an alternative to the harmful ingredients propylene glycol, and ethylene glycol,These studies have come from very conservative ingredient safety review groups such as the well respected CTFA. In general, the CTFA seems to confirm Neways suspicions regarding many other harmful ingredients. Nevertheless, butylene glycol is an ingredient that has been confirmed to be safe as a topical ingredient and even as an ingestible.

It has been examined by researchers and found to be as safe as many other natural ingredients.  It is not a known carcinogen.