Methyl bromide (MeBr) is a chemically reactive compound that has found use as a fire retardant and fumigant used for wood, soil, fruits and grains. Its use is banned in many countries because of its ozone-depleting properties. Despite this ban, the use of MeBr persists in some parts of the world (e.g. New Zealand) due to its important role in maintaining strict biosecurity of exported and imported products. Its high chemical reactivity leads to a broad toxicological profile ranging from acute respiratory toxicity following inhalation exposure, through carcinogenicity to neurotoxicty. In this article, we discuss the chemistry of MeBr in the context of its mechanisms of toxicity. The chemical reactivity of MeBr clearly underlies its toxicity. Bromine (Br) is electronegative and a good leaving group; the δ+ carbon thus facilitates electrophilic methylation of biological molecules including glutathione (GSH) via its δ− sulphur atom, leading to downstream effects due to GSH depletion. DNA alkylation, either directly by MeBr or indirectly due to reduction in GSH-mediated detoxification of reactive alkylating chemical species, might explain the carcinogenicity of MeBr. The neurotoxicity of MeBr is much more difficult to understand, but we speculate that methyl phosphates formed in cells might contribute to its neurone-specific toxicity via cholinesterase inhibition. Finally, evidence reviewed shows that it is unlikely for Br− liberated by the metabolism of MeBr to have any toxicological effect because the Br− dose is very low.

Aims: To investigate the ability of baker's yeast (Saccharomyces cerevisiae) to degrade the herbicide glyphosate during the fermentation cycle of the breadmaking process. Methods and Results: Aqueous glyphosate was added to bread ingredients and kneaded by commercially available breadmaking equipment into dough cultures. Cultures were incubated in the breadmaker throughout the fermentation cycle. The recovery of glyphosate levels following fermentation was determined, thus allowing an estimation of glyphosate degradation by yeast. Conclusions: It was shown, for the first time, that S. cerevisiae plays a role in metabolizing glyphosate during the fermentation stages of breadmaking. Approximately 21% was degraded within 1 h. Significance and Impact of the Study: As a result of projected increases in the glyphosate use on wheat and the role of bread as a dietary staple, this may contribute to more informed decisions being made relating to the use of glyphosate on glyphosate-resistant wheat, from a public health/regulatory perspective.

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There is worldwide controversy about the effects of surgical mesh; particularly following adverse events associated with its use for repair of pelvic organ prolapse in women. 1 This led to the USA Food and Drug Administration (USFDA) issuing a Public Health Notification in 2008. 2 These and similar actions in other jurisdictions began a debate on risk versus benefit of surgical procedures using surgical mesh as opposed to traditional suture-based repairs. Interest has focused on urogyecological procedures where there is a large body of data showing the problems associated with mesh use, including erosion through the vaginal epithelium and vaginal scarring. 3,4 The formation of scar tissue involves the deposition of collagen from fibroblasts which are stimulated to divide by transforming growth factor (TGF)-b 2 in response to tissue damage and the resulting inflammatory response. 5 The reported side effect of surgical mesh use are predominantly medium-term (i.e. 1-5 y); these follow up studies focused on quality of life, pain, return of symptoms, dysparuria, etc. and thus are not relevant to tumorigenesis. 6,7 Indeed, it is very unlikely that tumours would manifest in a 5-year timescale. Few data are available to facilitate robust assessment of long-term (>10 y) risks, and for other surgical procedures utilising surgical mesh, including abdominal hernia repair (for which surgical mesh was first used in the 1950s). 2 Long-term hernia repair follow-up studies focused on hernia recurrence, scar pain and cosmetic effects and concluded that mesh was superior to conventional suture-based surgical procedures based on these risk factors. 8,9 A 17-year follow-up study involved palpation to check for 'signs of erosion, extrusion, fistulation and other tissue reactions' after tension-free vaginal tape (TVT) procedures did not report any tumours. 10 However, it is likely that the palpation method would not detect small tumours, and the authors make the point that the amount of mesh implanted when TVT is used is much less than is used for prolapse surgery. 10