Rapeseed (syn. Canola) Revisited.

For a few weeks at about this time of year, parts of England’s ‘green and pleasant land’ turns into a nauseous Day-Glo yellow vista, as farmers submit us hapless country-lovers not only to hideous horizon-wide visual onslaught, but also to our annual toxic gassing of unpleasant volatiles from rapeseed flowers (Brassica napus spp. oleifera) coupled with a seasonal overload of rapeseed pollen.

Uses - bio-diesel & cosmetics.
When the UK crop matures, some of the fixed oil produced is sold for bio-diesel, mainly to Germany, according to an illustrated article in a recent Guardian supplement (Blythman 2007). Elsewhere, it is quoted that some 40-60% of European rapeseed production goes to bio-diesel production (Mudeva 2006); Apart from France, Poland is also among top rapeseed-oil producing countries, its’ output being quoted as 1.49 million tons in 2004  (Krukowska 2004), although UK production is expected to top 2 million tons in 2008 (Blythman 2007).  DEFRA have previously pointed out that 1 ton of rapeseed gives 0.38 tons of rape methyl ester (one possible bio-fuel, besides rape ethyl ester etc.). In other parts of the world, opposition to bio-fuels, especially bio-ethanol, has been vigorous (see Larouchepac 2006), but it hasn’t stopped the Canadian Agriculture minister in 2006 announcing $11 million in funding initiatives for Canadian farmers in biofuels opportunities (N.B. already 40% of the rapeseed grown in Canada is GM, according to Teitel 2001).

Supplementing diesel is apparently in line with the EU commitment to increasing the share of bio-fuelled transport to 10% (Kroeger, 2007), although this has bought criticism from many environmental NGO’s who say the policy will do more harm than good (Anon 2007). Some of these criticisms have been aired in the UK national press, such as the fact that land, which should be primarily set aside for food production, is being raffled off to appease the modern great God: the motor car. In a slightly different area, George Monbiot has criticized the UK government for not disqualifying palm-oil (which he maintains will actually worsen greenhouse gas discharges) from EU-driven bio-fuel targets (Monbiot 2006). True, a public consultation exercise on the bio-fuels policy topic was conducted by the EC (EC 2006), but as usual, the EC was more concerned with policy than practicality, and failed to ask views on the pertinent issues. 

A small amount of rapeseed oil is used in cosmetics, especially in soap-making, as a carrier for fragrances in 100% ‘natural’ perfumes, and as a diluent for candle fragrances, in lamp oils etc.  However considering rapeseed oil’s negative eco-associations above (nitrate leaching, crop spraying requirements etc.) this fragrance diluent usage stops at ‘natural’ perfumes and for obvious reasons does not extend to claims for ‘organic’ perfumes.

Rapeseed oil production – the negative aspects.

Committing a large area of agricultural land to growing rapeseed has a downside. Some of the issues here include:

1. The increased use of harmful crop sprays. Rapeseed is prone to widespread attack from a variety of insect & microbiological predators. An average crop might receive the following sprayings: 3 of herbicides, 2 of fungicides & 2 of insecticides per growing season (Office of National Statistics through Blythman 2007). Insecticides commonly used include glufosinate ammonium & the hormone disruptor vinclozolin.

2. Possible eco-damage. Rapeseed crop production is associated with higher demands for nitrogen & sulphur-based fertiliser application, and excessive nitrate leaching into water sources is associated with rapeseed cultivation, causing localised environmental problems. In addition, decaying rapeseed vegetation (in common with other Brassica spp.) is known to put thiocyanate into the soil (Brown & Morra 1993), & soils treated with defatted rapeseed meal were determined to yield 6µg/g of thiocyanate (Brown et al 1991), although please note that a determined chemical value for thiocyanate, & and its total bioavailability, may differ. Microbiological degradation over several days will offer the principle detoxification route for thiocyanate (Brown & Morra 1993).

However the Canadian Canola Board indicate that breeders of Canola varieties have reduced the glucosinolate contents in rapeseed meal (where the bitter taste of glucosinolates acts as a feeding deterrent). Already they claim Canadian Canola meal has only an average 16µg/mol total glucosinolates (and some years it has been lower than this), compared with traditional meal which contains 120-160µg/mol. Judging by the nitrile & isothiocyanate volatiles coming from flowering rapeseed fields in the UK, this sort of technology hasn’t yet spared UK citizens from their annual gassing. 

3. The GM issue. Monsanto has been amongst those companies producing transgenic rapeseed varieties, modified to be resistant to RoundUp (known in Australia as RoundUp Ready canola). You may remember Monsanto previously hit the headlines when it prosecuted a Canadian farmer, who, it was claimed had allegedly infringed their property rights (wind-blown (?) GM rapeseed plants had appeared on his land). The judge, to the outrage of GM protesters, found for Monsanto (Teitel 2001), and although the case was later reviewed, the court still found for Monsanto (BBC 2004). The EC halted new approvals for GMO’s in 1998 due to intense consumer opposition, but the US filed a complaint at the WTO in 2003, supported by Argentina & Canada. The US action has been widely seen by EU consumers as bullying, and since the FDA has been involved in international GMO promotion, Cropwatch now sees this organization not as a reliable independent health authority, but as an authority hopelessly tainted by political influence.

In 2004 the EU introduced labeling & traceability procedures for GMO’s, but meanwhile the US has proved to be the leading source of global GM contamination. For example between 2001 & 2004 hundreds of tons of maize contaminated with Sygenta’s unapproved transgenic variety Bt10 were distributed world-wide and entered the global food chain, without the US authorities noticing for these  four years…

The EC, in a totally undemocratic move, authorised Monsanto in August 2005 to be allowed to grow the GM rapeseed variety GT73 in Europe for 10 years, going against the wishes of the EU member states, 13 out of 25 of whom had voted against the proposal. The EU Commissioners seem, for unknown reasons, keen to promote GM technology throughout Europe, and are out of touch with the opinions of the majority of EU citizens who maintain a strong anti-GM stance. A more recent evaluation of the safety of GM canola, including the explaining away of increase in liver weights of rats fed GT73 canola, is to be found at FD Govt Au (2007). 

The European Commission just recently authorized the Bayer Chemical Company to be allowed grow three GM rapeseed varieties in Europe for the next 10 years, modified to resist glufosinate ammonium.

And so it goes on….

4. Allergic Reactions
According to my unscientifically-based observations (i.e. talking to some UK GP’s), rapeseed pollen causes untold seasonal respiratory misery for a proportion of the (rural?) UK population, but this fact is apparently disputed by oilseed organizations. The scientific press shows little clear direction on the issue either – just a handful of articles, both for (e.g. Focke et al. 1998; Hemmer et al. 1997) and against (e.g. Guylling 2006) an allergic association. Previously Parrat et al. (1995) had shown in a Scottish study that allergic reactions were not directly related to airborne pollen levels, although Welch et al. (2000) ruled out cross-reactivity with grass pollen. Soutar et al. (1994) investigating 1000 people from the Aberdeen area had suggested the prevalence of symptoms was small and could be caused by chemicals from the crop chemicals. Similarly Murphy (1999) had concluded that rapeseed allergenicity only had a minimal impact on health. An article by Butcher et al. (1994) looked for possible aeroallergens/irritants & identified 22 volatiles from rapeseed flowers.

More recent studies paint a more illuminating picture, however. Children with IgE-mediated allergy to foods often show reactions to rape seeds in skin prick tests (pathways unknown). Puumalaein et al. (2005) have shown that 2S albumins (seed storage proteins) may be responsible for the rapeseed food allergy, and investigations characterising these proteins being investigated by Palomeres et. al. (2002).  More recently, Fiorina et al. (2003) employed an in situ aerobiologic test to detect the presence of a rapeseed allergen, where routine tests had failed, and Hermanides et al. (2006) describe cases of occupational allergy to Brassica pollens.

It seems that science has yet to catch up with UK people’s anecdotal experiences of eye & upper respiratory irritation from rapeseed volatiles or pollen and offer some explanations. Or is there a conspiracy of silence?  An excellent thread from 1996 on the Gentech archive (Gentech 1996) shows examples of academic unawareness (failing to find what published studies there are), UK ministerial indifference (no evidence, but revealed to be simply because of a lack of authoritative studies) and a surprising dearth of North American & Canadian anecdotal symptom reporting, in contrast to the UK experience. The Gentech article also provides 14 references related to allergenicity of rapeseed/rapeseed products – which had proved so hard for some authorities to find (err, no change there then!).

The persistence of public belief that rapeseed cultivation causes widespread seasonal respiratory distress has been remarked upon by Blythman (2007), who maintains (paraphrasing his words) that in the absence of a clear case of  causation, maybe we should own up to the fact that in the UK, we simply don’t like the stuff.

I, for one, am quite willing to own up to that fact.

Refs.
Anon (2007) “Brussels biofuels push met with skepticism.” – see http://www.euractiv.com/en/environment/brussels-biofuels-push-met-scepticism/article-160789

BBC (2004) see http://news.bbc.co.uk/1/hi/business/3736591.stm

Blythman J. (2007) “Seeds of Discontent.” The Guardian G2 19.04.07 pp4-8.  See also http://environment.guardian.co.uk/energy/story/0,,2060538,00.html?gusrc=rss&feed=1

Brown P.D., Morra M.J., McCaffrey J.R., Auld D.L. & Williams III L. (1991) "Allelochemicals produced during glucosinolate degradation in soil." J. Chem. Ecology 17(10), 2021-2034.

Brown P.D.  &  Morra M.J. (1993) "Fate of Ionic thiocyanate (SCN-) in Soil" J. Agric. Food Chem. 1003, 41, 978-982.

Butcher R.D., MacFarlane-Smith W., Robertson G.W., Griffiths D.W. (1994) "The identification of potential aeroallergen/irritant(s) from oilseed rape (Brassica napus spp. oleifera): volatile organic compounds emitted during flowering progression." Clin Exp Allergy. 24(12), 1105-14.

EC (2006) http://ec.europa.eu/energy/res/legislation/biofuels_consultation_en.htm
FD Govt Au - see “GM Canola safety assessment” at http://www.foodstandards.gov.au/newsroom/factsheets/factsheets2004/gmcanolasafetyassess2498.cfm

Fiorina A., Scordamaglia A., Guerra L. & Passalacqua G.(2003) "Aerobiologic diagnosis of brassicaceae-induced asthma" Allergy 58 (8), 829–830.

Focke M., Hemmer W., Hayek B., Gotz M. & Jarisch R. (1998) "Identification of allergens in oilseed rape (Brassica napus) pollen." Int Arch Allergy Immunol. 117(2), 105-12

Gentech (1996): see archive at http://www.gene.ch/gentech/1999/May-Jun/msg00001.html

Gylling H. (2006) "Rapeseed oil does not cause allergic reactions." Allergy 61(7), 895.

Hemmer W., Focke M., Wantke F., Jager S., Gotz M. & Jarisch R. (1997) "Oilseed rape pollen is a potentially relevant allergen." Clin Exp Allergy 27(2), 156-61.

Hermanides H.K., Lahey-de Boer A.M., Zuidmeer L., Guikers C., van Ree R., & Knulst A.C. (2006) "Brassica oleracea pollen, a new source of occupational allergens." Allergy 61(4), 498-502.

Kroeger A. (2007) “Denmark Seeks bio-fuel solutions.”  http://news.bbc.co.uk/2/hi/europe/6539379.stm

Krukowska E. (ed) (2004) “Polish bio-diesel output seen surging on law change.” – see http://www.planetark.org/dailynewsstory.cfm/newsid/35623/newsDate/14-Mar-2006/story.htm

Larouchepac (2006) – see http://www.state.sd.us/puc/commission/dockets/electric/2005/el05-022/hearing/pubicmeetingexhbitneson2.pdf

McEwan M., Macfarlane Smith W.H. “Identification of volatile organic compounds emitted in the field by oilseed rape (Brassica napus ssp. oleifera) over the growing season."  Clinical Exptl Allergy 28(3), 332.   

Monbiot G. (2006) – see http://www.monbiot.com/archives/2005/12/06/worse-than-fossil-fuel

Mudeva A. (2006) “Food Industry calls for bio-diesel alternatives.” – see
http://www.planetark.com/dailynewsstory.cfm?newsid=35885&newsdate=04-Apr-2006

Murphy D.J. (1999) "Is rapeseed really an allergenic plant? Popular myths versus scientific realities." Immunology Today 20 (11), 511-514.

Palomares O., Monsalve R.I., Rodríguez R. & Villalba M. (2002) "Recombinant pronapin precursor produced in Pichia pastoris displays structural and immunologic equivalent properties to its mature product isolated from rapeseed." Eur. J. Biochem. 269, 2538-2545. 

Parratt D., Macfarlane Smith W.H., Thomson G., Cameron L.A. & Butcher R.D. (1995) "Evidence that oilseed rape (Brassica napus ssp. oleifera) causes respiratory illness in rural dwellers." Scott Med J.  40(3), 74-6.

Puumalainen T.J., Poikonen S., Kotovuori A., Vaali K., Kalkkinen N., Reunala T., Turjanmaa K, Timo Palosuo T. "Napins, 2S albumins, are major allergens in oilseed rape and turnip rape." Journal of Allergy and Clinical Immunology 117(2),426-432.

Teitel M. (2001).  “There you go again, Monsanto.” – see http://www.gene-watch.org/genewatch/articles/14-4monsanto.html

Welch J., Jones M.G., Cullinan P., Coates O.A., & Newman Taylor A.J. (2000) "Sensitization to oilseed rape is not due to cross-reactivity with grass pollen." Clin Exp Allergy. 30(3), 370-5.