The authors of a study published in the journal Food and Chemical Toxicology said that the environmental impact of chewing gum litter and the economic costs associated with removing it are significant.
Chewing gum is a multibillion-dollar industry, with US consumers chewing as much as 2.5 kg of gum per capita annually, which is equivalent to approximately 6.9 g per person, or a little over 3.5 average sticks of gum per day.
According to the authors, the novel polymer Rev 7 offers an alternative gum base for manufacturers that is non-adhesive.
The article explains that the polymer, produced by UK-based Revolymer, is a synthetic one that contains a hydrophilic component, which renders it non-adhesive to surfaces often littered with gum such as pavements, clothing, carpets and furniture.
The authors said that in order to establish a safety profile for the synthetic polymer, Rev 7 was screened for a battery of compounds that could theoretically contaminate the product during the manufacturing process including monomers, solvents, metals, and other potential by-products.
In addition to this screening, several genetic and oral toxicology tests were performed, they said, including the bacterial reverse mutation assay (AMES), the mouse lymphoma thymidine kinase gene mutation assay, the mammalian erythrocyte micronucleus test and a 28-day repeated oral toxicity study in rats.
Finally, in order to determine the possible risk of Rev 7 in terms of skin sensitization reactions, a murine local lymph node assay was performed on the ingredient, said the authors.
The results of the safety assessment, they noted, showed that analytical testing for heavy metals, monomers, solvents and additives present in the tested batches of Rev 7 were all within safe limits, and it was non-mutagenic in an AMES assay, added the authors.
“The highest concentration tested in a mouse lymphoma thymidine kinase locus gene mutation assay induced a slight but biologically relevant increase in mutations under non-metabolic activation conditions after 24 hours.
“Because of this finding, a mouse micronucleus assay was performed, and the test article was found to be negative for inducing chromosomal damage,” states the article.
According to the article, a 28-day 30 repeated oral toxicity study resulted in a NOAEL (No Observed Adverse Effect Level) of 80,000 ppm; the highest concentration tested. And the authors also reported that Rev 7 did not demonstrate skin-sensitizing properties.
In terms of its use in gum, the authors suggest that Rev 7 should consist a maximum of 15 per cent of the total gum weight (Patent WO/2006/016179), resulting in consumption of up to 1.04 g per day. As an extra precaution this level was doubled to 2 grams for calculating concentrations of metals and monomers.
Source: Food and Chemical Toxicology
Published online ahead of print: doi:10.1016/j.fct.2009.12.017
Title: Safety assessment of a novel ingredient for removable chewing gum
Authors: T.M. Farber, A.E. Clewell, J.R. Endres, J. Hauswirth, M. Van Gemert, A.G. Schauss, C.A. Sheane