Fish, mutagenic activity

Epidemiologic studies in Japan indicate an increased risk of stomach cancer owing to consumption of broiled fish and meats (116). In the United States, stomach cancer incidence has steadily declined since the 1940s, whereas consumption of broiled food has increased (108). In addition, the average human intake of PAHs is only 0.002 of that required to produce cancer in half of animals fed. Test results are often contradictory (117) and many components of food, such as vitamin A, unsaturated fatty acids, thiols, nitrites, and even saUva itself, tend to inhibit the mutagenic activity of PAHs (118—120). Therefore, the significance of PAHs in the human diet remains unknown (121,109). 

The mutagenic activity of the extracts was assayed using Salmonella typhimurium strain TA 1535, as described by McCann et al. (58). Ten ul of fish extract were spot-tested without addition of an S9-enzyme preparation (57). MNNG (20 ug/plate) was used as a positive control. 

No mutagenic activity could be detected in the bile of bream from the Meuse River, which contains little activity in the water itself. Seasonal changes in the level of Rhine water mutagenicity roughly coincide with similar changes in the activity of bile from Rhine fish (see Figure 8). 

Figure 8. Variations in mutagenic activity of fish bile extracts of the Rhine...

The first intimation that mutagens could be formed from natural food substances came from the laboratory of Sugimura, where it was found that mutagenic activity was found in smoke condensates or in DMSO extracts of the charred surface of fish and meat. This activity could not be accounted for by the amounts of BaP and PAH known to be present. Extracts of pyrolysates of various proteins and amino acids were also mutagenic (14). 

Mutagenic activity is also present in broiled herring, mackerel and sardine (11,12,22). In part, these mutagens were later identified as Trp-P-1 and Trp-P-2 (12) and IQ and 2-amino-3,4-dimethylimidazo [4,5-fJquinoline (Me-IQ)(13). In addition, Bjeldanes e t a. (23) have also reported mutagen formation in pan-fried fish, such as rock cod, sole, halibut, trout, salmon and red snapper. However, the mutagenic activity is low compared to that in beef. 

As would be expected from the results of studies on model systems, it has been found that foods with a high starch or sugar content may form genotoxic substances, but at a much lower level than meats or fish. Spingarn et al (65) showed that several common foods, in addition to beef, contained mutagens active for TA98 in the presence of S9 (Table V) Pariza et al. (66) found mutagenic activity in basic fractions of chicken broth, beef broth, rice cereal, bread crust, crackers, corn flakes, toast and cookies. 

Bisphenol A (BPA), an endociine-disrupting chemical, is commonly found in food packaging and can coatings. Nitrate is found in vegetables, fish, and in potable water as a pollutant. Bisphenol A alone did not exhibit mutagenicity toward Salmonella typhimurium strains TA 98 and TA 100 after incubation at pH 3.0 to simulate human stomach conditions. When nitrate was added to bisphenol A, however, the mixture showed strong mutagenic activity [107]. 

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