pressure. Possible health hazards of pickled vegetables The World Health Organization has listed pickled vegetables as a possible carcinogen, and the British Journal of Cancer released an online 2009 meta-analysis of research on pickles as increasing the risks of esophageal cancer. The report, citing limited data in a statistical meta analysis, indicates a potential two-fold increased risk of oesophageal cancer associated with Asian pickled vegetable consumption. Results from the research are described as having "high heterogeneity" and the study said that further well-designed prospective studies were warranted. However, their results stated "The majority of subgroup analyses showed a statistically significant association between consuming pickled vegetables and Oesophageal Squamous Cell Carcinoma". The 2009 meta-analysis reported heavy infestation of pickled vegetables with fungi. Some common fungi can facilitate the formation of N-nitroso compounds, which are strong oesophageal carcinogens in several animal models. Roussin red methyl ester, a non-alkylating nitroso compound with tumour-promoting effect in vitro, was identified in pickles from Linzhou, Henan (formerly Linxian) in much higher concentrations than in samples from low-incidence areas. Fumonisin mycotoxins have been shown to cause liver and kidney tumours in rodents. A 2017 study in Chinese Journal of Cancer has linked salted vegetables ( common among Chinese cuisine) to a fourfold increase in nasopharynx cancer. The researchers believe possible mechanisms include production of nitrosamines (a type of N-nitroso compound) by fermentation and activation of Epstein–Barr virus by fermentation products. Historically, pickling caused health concerns for reasons associated with copper salts, as explained in the mid-19th century The English and Australian Cookery Book: "The evidence of the Lancet commissioner (Dr. Hassall) and Mr. Blackwell (of the eminent firm of Crosse and Blackwell) went to prove that the pickles sold in the shops are nearly always artificially coloured, and are thus rendered highly unwholesome, if not actually poisonous." Risk reduction Reduction of suspected carcinogens from pickled products is a subject of active research. Fungi are of interest both for spoilage prevention and reduction of mycotoxins. Some pickle cultures are said to contain bacteria producing natural antifungals. Nitrites, responsible for the creation of N-nitroso compounds, is reduced by low pH and/or high temperature. Inclusion of a porcini enzyme (or the whole mushroom) also reduces nitrite content. Gallery See also Curing (food preservation) Smoking (cooking) References External links Fermented Fruits and Vegetables: A Global Perspective—Food and Agriculture Organization of the United Nations National Center for Home Food Preservation: How do