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.
- 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.
- 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).
- 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.
- 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.
- 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.
- 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.
- 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).
- 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.”
This man is truly worth his weight in gold (Au). ;)
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.
Labels: food safety