Do GMO crops promote food allergies?

Post hoc, ergo procter hoc?

Stories that GM crops cause allergies are on the rise again, for instance in a recent annoucement of a new book, Genetic Roulette by Jeffrey Smith. Lets start by stepping back in history to the times of first introductions of GM crops.

Here is a copy of what colleague Wayne Parrott wrote back in 1999 after an article in the London Free Press said soy allergies were on the increase:

Date: Mon, 26 Jul 1999

Basically, the 1999 transgenic soybean crop has not been harvested yet. It also takes about a year between the time the soybean crop is harvested and the time it ends up on the supermarket shelves. Hence, the 1998 crop is just now making it to the supermarkets, so it cannot be blamed for any allergies.

That just leaves the 1997 (and first) soybean transgenic crop. An estimated 12% of the US crop was transgenic that year, and the US accounted for 49% of world production. That means that no more than 6% of the beans available to consumers could possibly have been transgenic, so I am having trouble believing that that is enough to account for a "sharp increase" in soy allergies.

Some further information on soy: The oil is the soyfood most often consumed by humans. Since oil is protein and DNA-free, oil from nontransgenic and from roundup-ready soybeans is identical-- there would be no biological basis for attributing an increase in allergenicity to the oil. That just leaves the meal left over after crushing the soybeans. 97% is fed to animals, and only 3% is used as ingredients for human food.

So, to answer the original question, I do not believe the statement that transgenic soy allergies are increasing due to the availability of transgenic soy. Likewise, the vast majority of the statements in the original London Free Press article are either false, misleading, or distorted through the omission of relevant details.

EPILOGUE-- allergies to soybean and other legumes are on the rise around the world. One hypothesis? Peanuts. Peanuts are highly allergenic. One a human becomes allergic to a peanut protein, they can become allergic to homologous proteins in other legumes.

Thanks to an Italian colleague Piero Morandini, Pundit has tracked down comments by the repected British Medical Journal that are also very relevant to the GMO allergy Issue:
British Medical Association Genetically modified foods and health: a second interim statement, 2004

Conclusions regarding GM foods and health (page 6)

Epidemiological health surveillance will remain impractical while so few of the UK population are exposed to GM foods. In the USA where a much larger proportion of the population has been exposed, food-derived illnesses are on the increase, although any suggestion that this could be linked to GM foods is not supported by scientific evidence. It is noteworthy that hospital admissions for systemic allergic disorders, including food allergy, increased significantly in England between 1990-91 and 2000-01 despite very low levels of exposure to GM foods. However, this debate underlines the need for the UK to take steps now to improve its nutritional and related health surveillance.

The BMA still considers that with several caveats (notably adequate risk assessment procedures, independent and rigorous testing of novel foods, adequate post marketing surveillance and proper regulation), genetically modified food has enormous potential to benefit both the developed and the developing world in the long-term. Continuing sound scientific research will provide the only means of eliminating the uncertainty that still surrounds the environmental and health impact of GM crops.

The full BMA report provided citations to the following paper, giving statistical detail.


Paper Title and Link: Increasing hospital admissions for systemic allergic disorders in England: analysis of national admissions data

BMJ 2003;327:1142-1143 (15 November), doi:10.1136/bmj.327.7424.1142

Ramyani Gupta, Lung and Asthma Information Agency epidemiologist,
Aziz Sheikh, NHS/PPP national primary care post doctoral fellow,
David Strachan, professor of epidemiology,
H Ross Anderson, professor of epidemiology and public health
Department of Community Health Sciences, St George's Hospital Medical School, Cranmer Terrace, London SW17 0RE

In this Gupta 2003 paper (follow link) you can see a nice graph with the increase in food allergies starting well before the advent of Roundup Ready soybeans, whose presence in the food must have been rather insignificant, as pointed out at the start of this post by Wayne Parrot.

With regard to the soybeans and increasing allergy claim, what bothers another colleague , Bruce Chassy most of all, is that it simply isn't a logical scientific conclusion.

The reader may recall from their school or college courses in clear thinking that this is called a post hoc fallacy. Just because an event follows another, it does not prove a causal link. Such observations can only be validly used as a basis for evaluating if the conjecture is merits testing.

This allergy issue does not merit expensive epimemiological testing for a number of reasons. Someone who makes such assertions is either illogical--which can fairly be pointed out--or they are being unethical when they are aware that their argument has zero validity.

Almost all of the anti-GMO arguments are logically flawed in some manner, fail the rules of evidence, and most certainly fail tests of bias and absence of conflict of interest.

...

The link at http://skepdic.com/posthoc.html provides those who skipped clear thinking courses with a discussion of the post hoc fallacy.

Pundit remembers Post hoc, ergo procter hoc from the distant past. It rolls of the tongue quite easily, and he thinks it means if you shut the stable door after the horse is bolted, the horse will come back, or something like that. He wasn't really paying attention that day and he doesn't really read Latin.


Update:

Allergies still on the rise in the EU but GM foods remain largely ON HOLD.

Then there is this, just in, as the best post hoc example yet :

The Organic Menace, via Agbioview

- Bureau Crash, 2006/04/08

In 2004 Crashers went to San Francisco for the Annual Biotech Convention in San Francisco and there were nearly 1,000 protestors in the streets. The following year, 2005, the convention was in Philadelphia and there were half that number of protestors. Today Chicago hosted the Bio convention and maybe 100 people showed up to protest it. Maybe.

There can be only one reason for this – organic food is killing off hippie protestors. I know what you’re thinking – with anecdotal evidence like this who wouldn’t be convinced? The science can’t be denied. While the general, biotech loving, population is growing the organic food crunching population is decreasing… rapidly.

So the question isn’t should the government get involved but how quickly. First, every single piece of organic produce will need a warning label. Second, there needs to be a public education campaign warning people about the dangers of organic food. Third, the Food & Drug Administration will need to research the risks associated with organic food. When the results come back as I expect we will then have the evidence necessary to pull this dangerous food from the market and burn the organic fields. This sounds drastic but we must put the public good before the interest of the organic food industry – or “Big Organic” as I like to call them.

Fast forward to June 2007
Allergy causes explained further by The hygiene hypothesis