Research that links Fonterra’s botulism scare with GM feed and herbicides is questioned

Science blogger Siouxsie Wiles has looked (here) at whether the Fonterra botulism scare can be attributed to herbicide use and GM crops. She finds the idea “highly questionable”.

She has cited an article at Stuff which reports Matamata veterinarian Frank Rowson, who says the contamination of Fonterra’s whey powder with the toxin-producing bacterium Clostridium botulinum is linked to contamination of the food chain by glyphosate weed killers.

Glyphosate is better known as the Monsanto product Round Up. The company developed genetically resistant crops so that farmers could use glyphosate to kill weeds without killing their crops.

Frank Rowson is quoted as saying he has research showing that:

“GM feeds and the use of increased amounts of glyphosate herbicides increases the prevalence of this disease in pigs, poultry and dairy cattle, and the neuro toxin that causes the disease will pass through the food chain into milk.”

Wiles notes, firstly, that Fonterra and the Ministry for Primary Industries have made clear it was not the toxin but the bacterial spores that contaminated the whey powder.

So if we put that aside for the moment, what is the possibility of the spores passing into the food chain through milk?

Rowson seems to be referring to this paper by Krüger et al in the journal Anaerobe earlier this year (h/t to Thomas Lumley) [1]. Alas, the article is not open access so I haven’t been able to read it this evening but according to the abstract the normal intestinal microflora is critical in preventing C. botulinum from colonising the intestine, by producing toxins which inhibit the bacterium. The authors report that glyphosate is toxic to the most prevalent species of Enterococcus in the gastrointestinal tract and suggest that ingestion of herbicide could therefore lead to the colonisation of cattle by C. botulinum.

According to the Irish Department Agriculture, Food and the Marine, the C. botulinum toxin types that cause disease in cattle are C and D, which do not cause disease in humans.

Fonterra still hasn’t released information on the type of C. botulinum which contaminated its whey powder.

But given the recall, Wiles says, we can assume it was either A, B, E or F, the types which cause botulism in humans.

From this, she concludes, it would seem that Rowson’s claim that the source of the Clostridial contamination is linked to glyphosate usage and cattle is highly questionable.

The reference she provides is:

Krüger M, Shehata AA, Schrödl W, Rodloff A. 2013. Glyphosate suppresses the antagonistic effect of Enterococcus spp. on Clostridium botulinum. Anaerobe. 20:74-8. doi: 10.1016/j.anaerobe.2013.01.005. Epub 2013 Feb 6.

A media statement from the Soil and Health Association can be found here.

It is headed GE feed the cause of contaminated milk?

It notes that New Zealand dairy cattle are eating more and more GE stockfeed, increasing the likelihood of botulism from milk products.

It, too, cites Frank Rowson.

In May this year, it says, Soil & Health’s magazine Organic NZ published an article by Matamata vet Frank Rowson, warning that glyphosate-based herbicides (found in many GE crops) cause increases in the virulence of pathogens, leading to more botulism and salmonella.

”We stand by our demand made in December last year and call for an immediate ban on all imported GE stockfeed until its role in milk contamination has been investigated fully,” says Swanwick.

Most of the soy in New Zealand stockfeed is now genetically engineered, she maintain,s but some retailers have or are intending to change suppliers and buy from India and South America to produce GE free lines.

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