Thursday, February 15, 2007

Fear & Genotoxins

There has been a lot of positive press lately about the purported food safety benefits of irradiated foods. Very little attention has been given to skeptics, at least few have been allowed to flesh out their arguments with cold, hard facts. As a result, I feel I need to share with you the work of a prominent toxicologist from the Univeristy of Texas, William Au, who present a well-informed voice of dissent.

Forgive me for lengthily quoting from a court document, wherein he presents expert testimony against the construction of a fruit irradiation facility in Hawaii, but I felt this was highly relevant to the recent interest in irradiating produce. I have attempted to bold-face information I find particularly informative, for those of you who would prefer to skim through it.

  1. The use of radiation to treat produce destined for human consumption for fruit flies and other agricultural pests should be evaluated for health concerns very carefully. Radiolytic products are formed during the irradiation of food (Schubert, 1969). Some radiolytic products are unique to the food irradiation process, and there are scientific data indicating their potential health hazards. More research is needed on the products that are unique to the irradiation process.
  2. A recently-discovered unique class of radiolytic products that are generated from the irradiation of fat-containing food is 2-alkylcyclobutanone (2-ACB) with saturated and monounsaturated alkyl side chain: 2-decyl-, 2-dodecyl-, 2-dodecenyl-, 2-tetradecyl- and 2-tetradecenyl-cyclobutanone (Miesch et al., 2002). Studies have confirmed the presence of 2-ACBs in irradiated mango and papaya, two types of fruit proposed for processing at the Pa’ina Hawaii facility, should it be approved (Ndiaye et al. 1999; Stewart et al., 200).
  3. Since 1998, concern regarding health hazards from the consumption of irradiated food has been focused on the toxicity of 2-ACB. Using in vitro assays, 2-ACB has been shown to be genotoxic and mutagenic (Delincee and Pool-Zobel, 1998; Delincee et al., 1998; Delincee et al., 2002; Burnouf et al., 2002). 2-ACB has also been tested in experimental animals. In one report (Horvatovich et al., 2002), laboratory rats were fed a very low concentration of 2-ACB in drinking water, and the absorption and excretion of the chemical were monitored. The study showed that less than 1% of the administered chemical was excreted in feces. A portion of the chemical crossed the intestinal barrier, entered the blood stream and accumulated in the adipose tissues of the animal. It follows that consumption of irradiated food for a long time can cause accumulation of toxic 2-ACB in the adipose tissues of human consumers.
  4. The recent findings by Raul et al. (2002) raises a high level of concern. In the study, Wistar rats received a daily solution of 2-tetradecylcyclobutanone or 2-(tetradec-5’-enyl)-cyclobutanone and a known colon carcinogen (azoxymethane [AOM]). Observations were made at two distinct intervals. At three months after initiation of the exposure, no significant changes in the number of pre-neoplastic colonic lesions were observed among the rats (all were exposed to AOM). At six months, however, the total number and the overall size of tumors were markedly increased in the 2-ACB-AOM treated rats as compared to the ethanol-AOM control rats. This demonstrates that compounds found exclusively in irradiated dietary fats may promote colon carcinogenesis in animals treated with a known carcinogen and identifies a new area of toxicity that neither the U.S. Food and Drug Administration nor the World Health Organization has yet examined.
  5. A promoting agent does not usually cause cancer by itself but alters cellular functions (Zheng et al., 2002; Yamagata et al., 2002). The unique concern with promoters is that they can significantly enhance the carcinogenic effects of known carcinogens (Hecker et al., 1980; Slaga, 1983; Langenbach et al., 1986). Experimental animals that are treated with both promoters and carcinogens develop tumors much earlier and have more tumor nodules than animals treated with the carcinogens alone. Animals treated with the promoters alone would not develop tumors more often than the untreated animals.
  6. Colon cancer (as was discovered in the rat study on 2-ACBs) is a serious health problem in humans, causing approximately 60,000 deaths per year in the United States. Consumption of improper diet is a major cause for colon cancer: foods that are high in fat especially from animal sources, meat cooked with high heat, charred meat, and food with high content of aromatic/heterocyclic amines (Colon cancer folder in the American Cancer Society website – http://www.cancer.org/; Lang et al., 1986; Vineis and McMichael, 1996). Consumption of the improper diet together with food that contains 2-ACB, which acts as a tumor promoter, can increase the risk for the development of colon cancer. Under this scenario, individuals who would normally outlive the risk for colon cancer might develop the cancer.
  7. Numerous other peer-reviewed published reports have long indicated the mutagenic activities of irradiated foods fed to mammals (Anderson et al., 1980; Bhaskaram and Sadasivan, 1975; Bugyaki et al., 1968; Maier et al., 1993; Moutschen-Dahmen, et al., 1970; Vijayalaxmi, 1975, 1976, 1978; Vijayalaxmi and Rao, 1976; Vijayalaxmi and Sadasivan, 1975). While the health concerns for consumption of irradiated food simply cannot be considered to have been resolved conclusively (Louria, 2001), the data indicate that consumption of irradiated food can cause genotoxic effects and therefore health hazards in the population. Moreover, there may be subpopulations, such as children, who are most susceptible to toxic effects of irradiated food. Strong reasons exist for considering children generally to be especially susceptible to toxic materials (Au 2002).
  8. In the final analysis, the only thing certain about the impacts on human health associated with the consumption of irradiated food, including the papayas, mangos, and other produce proposed to be processed at the Pa’ina Hawaii facility, is that it is the subject of considerable scientific debate. A recent article I co-authored summarizing the controversy over this issue (Ashley et al., 2004) is attached hereto as Exhibit “C” and incorporated herein by reference.

I find it interesting that Exhibit “C” was not, in fact, to be found attached, even while Exhibit “B” was clearly included, but after a little sleuthing, I found the abstract for the document, titled “Health concerns regarding consumption of irradiated food.”

Food irradiation is being promoted as a simple process that can be used to effectively and significantly reduce food-borne illnesses around the world. However, a thorough review of the literature reveals a paucity of adequate research conducted to specifically address health concerns that may directly result from the consumption of irradiated food. . . . As a result of this review, the authors conclude that current evidence does not exist to substantiate the support or unconditional endorsement of irradiation of food for consumption. In addition, consumers are entitled to their right of choice in the consumption of irradiated versus un-irradiated food.

This man is truly worth his weight in gold (Au). ;)

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6 Comments:

At February 15, 2007 4:52 PM, Blogger arved.deecke said...

You might want to add that Ndiaye et al. traced 2ACB's eclusively in the seedlings of mango and papaya where sufficient lipids for 2ACB formations can be found. Seeds of such fruit are not usually consumed and thus suggesting a health risk associated with consumption of irradiated tropical fruit based on this research is misleading. Please also consider referencing the Sommers, C.H. 2005 publication Toxicology Testing Of The Unique Radiolytic Product 2-Dodecylcyclobutanone were no 2-DCB induced mutagenesis was observed in any of the test systems, both with and without exogenous metabolic activation.

 
At February 16, 2007 9:04 AM, Blogger Jade said...

While it might be true that no one eats mango seeds, many people eat avocados -- a high fat fruit. If fruit fats are equally susceptible to forming 2ACBs, I find that relevant to this discussion. Would regulatory authorities make the distinction between irradiating spinach and irradiating avocados?

I guess I felt it was important to plant a seed of doubt regarding irradiated foods, since I am of the mind that unless something is proven COMPLETELY safe, I don't feel it is an improvement to our existing foodstuffs. When weighing the risk of immediate acute illness and long-term chronic illness, I would prefer to take the risk of immediate acute illness. Perhaps others would prefer to suffer through years of chemotherapy. It should be an informed choice that each person makes regarding their own health. Irradiation is an extreme "safeguard," which in my opinion requires numerous studies showing harmlessness.

I will look into the Sommers 2005 paper. But again, an extreme change to the food system requires the burden of proof of its safety. Not just one scientific paper showing no harm. ANY doubt should put the brakes on using such a draconian technology.

 
At February 16, 2007 9:33 AM, Blogger Jade said...

Dear Readers,

In the interest of full disclosure, I would like to inform you that arved.deecke may very well be the same -- Arved Deecke CEO of PHYTOSAN S.A. de C.V, Guadalajara, Mexico. You can find his company's website here. In my opinion, his bias is clear.

Dear Arved Deecke

I appreciate that you presented your argument using available scientific data. I understand why you chose to defend this technology, however I believe more than anything that people have the right to make informed decisions regarding their own health. When safety isn't 100% clear, people need to know the risks they take. My bias is obvious here, yours was not as easily discernable to the general public. I felt it was my duty to my readers to clarify your bias. My readership is composed of people who are concerned about healthy eating, which is a small segment of the population. While you are certainly welcome to add your perspective, please understand that I will be defensive of mine.

 
At February 16, 2007 10:25 AM, Blogger Jade said...

Re: Sommers 2005 -- any results pointing to lack of harm from 2-DCBs, does not negate the findings of harm due to 2-ACBs. 2-DCBs are formed from one class of fat -- palmitic. 2-ACBs would still be present from other classes of fats present in meats or other foods. The finding of no harm from 2-DCBs was reported by a USDA scientist. Some might argue this presents a bias. This is not independently funded research we are discussing.

 
At February 16, 2007 12:02 PM, Blogger PeakEngineer said...

Dang, you're posting faster than I can keep up with! :) I honestly had no idea there was legitimate concern with irradiated food -- it always seemed to me that the concern was more with the name that the actual process. Something else to add to my understanding of the nature of what we eat...

 
At February 16, 2007 2:26 PM, Blogger Jade said...

Thanks, Peak Engineer, I'll remember to restrain myself in the future. :)

I think you speak for the masses, PE. I also think there is a general perception that health-conscious consumers are over-reactive at times. I personally get a little concerned whenever foodstuffs are chemically altered, because our bodies evolved to specifically process certain natural chemical arrangements, but not altered or synthetic ones. That isn't to say all synthetic chemicals are bad for the human body, but that some could have unforseen consequences.

 

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