Well, this is terrifying. Especially note the bolded part. Wow! From the Guardian:
Antibiotics and herbicides, as it turns out, don’t mix. At least that’s the conclusion of a study published today in mBio, the peer-reviewed journal of the American Society for Microbiology, which found that if someone is exposed to both herbicides and antibiotics at the same time, higher doses of antibiotics will likely be needed to kill the offending bacteria.
…The study comes a week after glyphosate, an agricultural herbicide produced by Monsanto and more commonly known as RoundUp, was deemed “probably carcinogenic” by the World Health Organization.
The level of herbicide exposure tested in the mBio research was higher than what would generally be found as residue on food, but lower than application standards for commercially available herbicides. The level is compatible with the amount that people in rural areas can be exposed to from herbicide drift – the wind distributing chemicals sprayed in one field across many other plots of land – and what urban dwellers might be exposed to from using herbicides in their own or their neighbors’ gardens.
“The exposure pathways that we identified as possibly being the most relevant for future study generally arose from the use of the herbicide by others – for example, in the urban setting” Heinemann said. “Therefore, it may take communities talking to each other to find ways to reduce unintended exposures.”
Heinemann and his fellow researchers tested various combinations of three of the most commonly used herbicides: dicamba (sold commercially under the name Kamba); 2,4-dichlorophenoxyacetic acid; and glyphosate (RoundUp). They also studied five different classes of antibiotics: ampicillin, ciprofloxacin, chloramphenicol, kanamycin, and tetracycline.
In some cases, certain combinations of herbicide and antibiotic either improved the performance of the antibiotic or had no effect on the antibiotic at all. But in the majority of cases, the herbicide made the antibiotic less effective.
More research, though, is needed, and agrichemical producer Monsanto is in agreement with Heinemann over what needs to be studied next: whether or not it’s the active ingredient of these herbicides that affects antibiotics.
“It is difficult to separate the effect of surfactants, which are known to have an impact on cultured microbes, from the active ingredients,” said Charla Lord, a spokesperson for Monsanto.