What are the disadvantages of eating salted fish, and what are the disadvantages to health?

Eating too much salted fish and bacon is quite harmful. These foods are rich in protein, which can't be completely prevented from deteriorating during curing and after storage, and will produce carcinogenic nitrite. Due to the custom of eating salted fish and bacon, the incidence of nasopharyngeal carcinoma is still high in southeast coastal provinces including Guangdong and Fujian. The incidence of nasopharyngeal carcinoma in Guangdong ranks first in the country, so it is also called "Guangdong cancer". Cancer can be asymptomatic. When patients realize that there is obvious lymphadenopathy, most of them have reached the middle and late stage, and it only takes 3 to 6 months from canceration to middle and late stage. Traditionally, Guangdong residents like to eat salted fish and bacon. The content of nitrite in these foods is extremely high, and nitrite and its compounds have been proved to be an important factor in carcinogenesis. In addition, the imbalance of intake of some trace elements caused by local natural environment, such as high nickel and low selenium, has also been confirmed by experimental animals to induce nasopharyngeal carcinoma. The investigation found that the content of nickel in soil, water and rice in areas with high incidence of nasopharyngeal gas in Guangdong was higher than that in other areas. The occurrence of nasopharyngeal carcinoma is also related to consanguinity and heredity.