Modified swedes, high in glucosinolates sprayed with toxic chemicals.

Article first appeared in Agrigator - New Zealand Agricultural Views 

New Zealand dairy farmers are starting to get a little bit grumpy. Cows are dying after eating swedes.

Hundreds of cows have died, liver damage appears to be a part of the story, and it is mainly cows that in-calf that are affected. Farmers have fed brassicas to dairy cows for decades, and are well used to managing the transition period. What’s new? The type of brassica (mutagenic – i.e. Not naturally developed) sprayed with a little researched herbicide called Telar (chlorsulfuron).

Science regarding the chemical?

These brassicas are herbicide tolerant to chlorsulfuron. Chlorsulfuron is a known reproductive/developmental toxin. (Also here). However that data is old. There is very little information regarding chlorsulfuron and its risk.

Fact is, it has hardly been studied for toxicity. The studies used by regulatory agencies are over 20 years old (see pages 23 & 24) The chemical companies design and pay for the toxicity studies (known as seller sponsored science) and directly supply them to regulatory agencies for assessment. There are no publicly available (Ie. Published in scientific journals) studies investigating the toxicity of chlorsulfuron. The agrichemical corporations that pay for the studies don’t want them publicly disclosed.

The US EPA’s toxicity data is limited. Occupational (farmer) exposure for chlorsulfuron is based on a NOAEL of 75mg/kg day is based on a 1991 Prenatal Developmental Toxicity Study (rabbit) (1991a).[1] Of course, toxicity has been established at lower levels (page 7), (page 13) but ignored. More information can be found in the US Federal Register. [2]
The only toxicity studies held with the WHO and FAO appear to be thirty years old(p.17-19). Europe’s recent EFSA Scientific Report reviewing Chlorsulfuron in 2008 used ancient, private 1991 studies (MRID 41983101) to provide the maternal (75mg/kg) and developmental (200mg/kg) NOAELs. Europe’s ADI of 0.2 mg/kg bw/day based on an unknown, unpublished 2 year rat study (possibly Wood 1980, as EFSA discussesinterstitial cell tumors).

Europe’s AOEL is 0.43 mg/kg bw/day based on the 1-year dog study for which there is no cited reference. [3]

Dupont’s 2012 safety data sheet lists 3 unpublished studies from 1980 and 1981. [4] New Zealand doesn’t appear to list a NOAEL for Telar/Chlorsulfuron. NZ’s HSNO database reveals little other than chlorsulfuron is very ecotoxic in the soil and aquatic environment. If you dive into the NZ EPA 2005 decision document for chlorsulfuron (link is a downloadable word doc.), which forms the basis of ongoing approval, you will find it contains no information regarding reproductive and developmental toxicity. [5] Since 2005 there has been no consideration of toxicity or recent research investigated of Telar/chlorsulfuronin New Zealand. [5]

Science regarding the combined chemically mutated seed (HT) and the chemicals applied?
Despite producing the HT line of brassicas that are tolerant to Telar – no-one scientifically assessed whether the full formulation which includes chlorsulfuron and its adjuvants on HT brassicas will be toxic to in-calf dairy cows – who are the most affected stock connected to swede deaths. It appears there were no safety trials.

As discussed, no-one has considered the toxicity of chlorsulfuron for over a decade, yet the application rates that are set for chlorsulfuron are based on the established NOAEL – from 20+ years ago. It is the authors opinion that due diligence has not been carried out. If residue tests for chemicals used in production have been carried out all farmers should have access to all the data, in addition to testing methodologies used by the laboratories.

Laboratories may be formally accredited but not follow transparent international testing protocols that extract the chemical properly. This can result in a false negative, not detected by the laboratory though present.

Confidentiality agreements are held between the corporation, select farmers, veterinary associations and Dairy NZ. It would appear that information is suppressed. Dairy cows dealing with transition onto swedes (with glucosinolates) have to deal with the combined toxicity of Telar (chlorsulfuron), but also glyphosate based herbicides, possibly diazinon (which like glyphosate inhibits acetylcholinesterase and is classified as a probable carcinogen), and chlorpyrifos insecticide (associated with birth defects) which are all approved for use over the growing season. Where is the science on cumulative toxicity?

Pregnant animals are always more susceptible to toxins.

Not just chlorsulfuron that may be contributing towards cumulative toxicity.

An integral part of most farmers spray regimes before drilling HT Brassica seed is Roundup. GBH is liberally applied to pasture, silage and forage. Its worrying toxicity, published in respected journals is not discussed in agricultural newspapers. In a study on Danish dairy cows, elevated glyphosate urinary levels were linked to a marked increase in biomarkers indicative of damage to liver and kidney function. Glyphosate has also been found to suppress beneficial gut bacteria. [6] If a cow’s gut is compromised by glyphosate, can it deal with transition onto brassicas? Particularly HT brassicas, chemically changed, with levels of glucosinolates which are toxic to cattle, up to 16 times higher than in an unmodified plant.

No science on that one. (Interestingly, glyphosate based herbicides like Roundup now have a quantity of published science advising of its reproductive, developmental, endocrine and carcinogenic toxicity and how it’s bad for the gut (and therefore immune system) and reproductive performance – but glyphosate is used a lot more so subject to more investigation. Chlorsulfuron has passed under the radar.)

When chlorsulfuron was assessed for toxicity it definitely wasn’t assessed as part of a modified stock feed that had undergone chemical mutagenesis.

Definitely not a GMO – but risky all the same.

New Zealand mainstream agricultural media also appear reluctant to consider possible toxicity of the Herbicide Tolerant (HT) swedes. They are not transgenic, instead, produced through chemical mutagenesis using chemical Ethylmethane Sulfonate (EMS). [7] These brassicas are as a result, genetically different from standard swedes, otherwise there would not be a patent held on them.

The WHO definition of a genetically modified organism is one where the genetic material (DNA) has been altered in a way that does not occur naturally by mating and/or natural recombination’ [8]

Chemical mutagenesis is certainly not natural, so why is it evading regulation? Perhaps Dairy NZ and farmers should be questioning why there are no released stock feeding trials where cows are eating the brassica plant, but also trials including dosages of the full formulation of herbicides contained in the spray regime recommended to partner the brassica product?
The non-GMO status of these brassicas does result in less risk assessment. Many scientists consider breeding via chemical mutagenesis as risky and unpredictableYet these HT brassicas follow similar procedure with GMO seed crops overseas.

Farmers who purchase HT seed are given a product endorsement to sign – no seed is delivered unless this is signed. PGG Wrightson’s Seed Manager David Green advised in October last year that this endorsement would be changed to state that pregnant dairy cows should not be fed the product. Therefore if more in-calf cows die, farmers can’t sue. … if liability was established.

Doesn’t an altered endorsement reflect an understanding that this product is in all likelihood, toxic to pregnant dairy cows?

Published studies have confirmed that genetically modified feed can compromise fertility, but also the uterus and gut of animals. [9] Most ruminants fed genetically modified feed are slaughtered within two years, unlike the longer lifetime of our dairy cows. But again, though the genes are altered chemically, this is not a GMO product, we simply have to assume safety.
It is important to recognise that the growth in patented seed product overseas has resulted in variety decline in existing, naturally bred seed stock. Seed prices in the US for (usually GMO) patented seed have increased along with less market choice and the patented product in the hands of a small amount of companies.

With these facts in mind, it is imperative that standard, safer, non-chemically altered brassica seed is kept in ample quantities for New Zealand farmers. Noting PGG Wrightson control 85% of New Zealand’s brassica seed supply.

Media coverage and Dairy NZ since September last year has shown a remarkable disinclination to discuss the potential systemic toxicity of the chemically mutated swedes in combination with the chemical regime they are associated with.

Much of mainstream media and Dairy NZ are quite content to discuss high levels of glucosinolates though.


It appears that:

1. Toxicity studies for chlorsulfuron are ancient, unpublished and private.
2. PGG Wrightson have amended the endorsement ‘not for pregnant dairy cows.’
3. It’s not just transitioning to a different feed type – there is more to the story.
4. The glucosinalate levels were off the chart – still classed as safe.
5. Where are the feeding trials of a plant modified by chemical mutagenesis with the dosages to mimic the recommended full formulation chemical regime?
6. No apparent analysis and testing or investigation of the chemicals used in the brassica crop may have interacted to contribute to systemic toxicity of in-calf cows.

Thorough transparent analysis is expensive. So are dairy cows. It is all about the science.


References and information:

[1] US EPA NOAEL: Alvarez, L. 1991a. Teratogenicity Study of DPX–W4189 (Chlorsulfuron) in Rabbits. E.I. du Pont de Nemours & Company, HaskellLaboratory for Toxicology and Industrial Medicine, Newark, DE, Laboratory Project ID:306–390, August 12, 1991. Unpublished

[2] Details of toxicity studies (only provided by the chemical company, in this case DuPont) appear most clearly in the US EPA Federal Register. 

[3] EU study – unclear as no reference provided – possibly:

Wood, C.K., Wollenberg, E.J., Turner, D.T., et al. 1981a. Long-Term Feeding Study with 2-chloro-N-6(4-methoxy-6-methyl-1,3,5- triazin-2- yl)aminocarbonylbenzenesulfonamide (INW– 4189) in Rats. E.I. du Pont de Nemours & Company, Haskell Laboratory Report No. 557–81, November 13, 1981. MRID 0086003. Unpublished. (interstitial cell tumors present)

NOTE: The Wood study was repeated and replaced by the following study (with no tumors):

Mylchreest, E. (2005b) Chlorsulfuron (DPX-W4189) Technical: Multigeneration Reproduction Study in Rats. Laboratory Project ID: DuPont-13475. E.I. du Pont de Nemours and Company, Wilmington, Delaware 19898, U. S. A.

 [4] Dupont Telar Herbicide Safety Data Sheet refers to 3 animal studies:

Schneider, P.W., Jr., Smith, L.W., Barnes, J.R., et al. 1980. Six-Month Feeding Study in Dogs with 2-Chloro-N-o(4-methoxy-6-methy-1,3,5-triazin–2yl)amino carbonyl benzenesulfonamide (INW–4189): Report No. 108–80. Final rept. (Unpublished study including pathology report no. 53–79, received Jun 16, 1980 under 352–EX–105; submitted by E.I. du Pont de Nemours & Co., Wilmington, DE; CDL:099461–A).  (4 female 4 male dogs were studied)

Wood, C.K., Wollenberg, E.J., Turner,D.T., et al. 1981a. Long-Term Feeding Study with 2-chloro-N-6(4-methoxy-6-methyl-1,3,5-triazin-2-yl)aminocarbonylbenzenesulfonamide (INW–4189) in Rats. E.I. du Pont de Nemours &Company, Haskell Laboratory Report No.557–81, November 13, 1981. MRID 0086003. Unpublished.  (80 rats were studied)

Wood, C.K., Wollenberg, E.J., Turner, D.T., et al. 1981b. Long-Term Feeding Study with INW–4189 in Mice. E.I. du Pont de Nemours & Company, Haskell Laboratory Report No. 836–81, December 28, 1981. MRID 0090030. Unpublished.

LD50: Content only available in Russian. Not possible to verify. Rakitsky, V.N. and Beloyedova, N.S. 2009. Toxicity and Hazardousness of Sulfonylurea Herbicides. Toxicology Herald.

[5]  The NZ application was for Agronica Chlorsulfuron Herbicide, a water dispersible granule containing 750 g/kg chlorsulfuron. ‘The substance will be used for the control of broadleaf weeds in wheat, barley and oats’. To be diluted before application to a concentration of 20 g in a minimum of 60 litres of water per hectare with a non-ionic surfactant. The application rate was set at 15 g ai /ha in cereals, once per season.

[6] a. Glyphosate suppresses the antagonistic effect of Enterococcus spp. on Clostridium botulinum. Krüger M1, Shehata AA, Schrödl W, Rodloff A. Anaerobe. 2013 Apr;20:74-8. doi: 10.1016/j.anaerobe.2013.01.005. Epub 2013 Feb 6.

b. Krüger M, et al. (2013) Field Investigations of Glyphosate in Urine of Danish Dairy Cows. J Environ Anal Toxicol 3: 186.

[7] Cleancrop™ Brassica System: The development of herbicide resistant brassica crops for New Zealand farming systems A. DUMBLETON1 , S. GOWERS2 , A. CONNER3 , M. CHRISTIE4 , P. KENNY1 , H. MULCOCK1 , and B. CHARTERIS1 1 PGG Wrightson Seeds Limited, PO Box 175, Lincoln 2 The New Zealand Institute for Plant and Food Research Limited, Private Bag 4704, Christchurch 3 AgResearch Ltd, Grasslands Research Centre, Private Bag 11008, Palmerston North

[8] WHO classification: Genetically modified organisms (GMOs) can be defined as organisms (i.e. plants, animals or microorganisms) in which the genetic material (DNA) has been altered in a way that does not occur naturally by mating and/or natural recombination. The technology is often called “modern biotechnology” or “gene technology”, sometimes also “recombinant DNA technology” or “genetic engineering”.

European Commission: In recent times, it has become possible to modify the genetic make-up of living cells and organisms using techniques of modern biotechnology called gene technology. The genetic material is modified artificially to give it a new property (e.g. a plant's resistance to a disease, insect or drought, a plant's tolerance to a herbicide, improving a food's quality or nutritional value, increased yield).

Such organisms are called "genetically modified organisms" (GMOs). Food and feed which contain or consist of such GMOs, or are produced from GMOs, are called "genetically modified (GM) food or feed".

[9] A long-term toxicology study on pigs fed a mixed GM diet. Adverse effects of GM crops found. By Dr. Judy Carman 11 June 2013