N-nitrozo bileşikleri ve halk sağlığına etkileri

N-Nitrozo bileşikleri, kimya literatüründe 20. yy'ın başından itibaren bilinen, ancak 1956 yılından sonra insan sağlığı üzerine etkileri daha çok dikkat çeken ve araştırılan bileşiklerdir. Deney hayvanları üzerinde yapılan araştırmalar sonucunda toksik, teratojenik, mutajenik ve kanserojenik etkilerinin olduğu belirtilmiştir. İnsanların N-nitrozo bileşiklerine maruz kalması genellikle iki şekilde gerçekleşmektedir. Birincisi, bu bileşikler gıdalarda katkı maddesi ya da doğal olarak bulunan nitrat ve nitritin çeşitli biyolojik aşamalar sonucu metabolize olmasıyla vücutta endojen olarak meydana gelmektedir. İkincisi ise, mikrobiyal dayanıklılığın artırılması amacıyla et ürünleri, balık ve peynirlere ilave edilen nitrit tuzlarının gıdaların içeriğindeki aminlerle tepkimeye girmesi sonucunda alımı şeklinde olmaktadır. N-nitrozo bileşiklerinin oluşumunda; besinlerin pişirilme şekli, pişirme süresi ve uygulanan ısı da etkilidir. Özellikle kızartılarak pişirilen nitritle kürlenmiş etlerde, N-nitrozo bileşiklerinin daha fazla oluştuğu bilinmektedir. Epidemiyolojik çalışmalar, insanlarda görülen kanser olgularının başlıca sebebinin (%60) beslenmeye bağlı olduğunu ortaya koymaktadır. Beslenmeden kaynaklanan kanserlerin azaltılması için potansiyel kanserojen N-nitrozo bileşiklerinin gıdalardaki miktarlarının denetimi titizlikle yapılmalı ve gerekli sınırlamalar uygulanmalıdır. Benzer şekilde, gıdalara koruma amaçlı olarak ilave edilen veya doğal olarak içeriğinde yer aldıkları gıdalar ile vücuda alınan nitrat ve nitrit miktarlarının azaltılması için gerekli çalışılmalar yapılmalıdır. Gıdalarda ve vücutta, N-nitrozo bileşiklerinin oluşumunu önleme özelliği bilinen askorbik asit (C vitamini) ve alfa-tokoferol (E vitamini) gibi antioksidanların katkı maddesi olarak uygun miktarlarda gıdalara eklenmesi veya antioksidan özelliğe sahip bileşiklerin diyetlerde yeterli miktarda alınması konusunda üreticiler ve tüketiciler bilinçlendirilmelidir.

N-nitroso compounds and their effects on public health

N-Nitroso compounds were known in chemical literature since the beginning of the 20th century, but their effect on human health received much attention since 1956. Experiments on animals showed toxic, teratogenic, mutagenic and carcinogenic effects. Human beings are generally exposed to these compounds via two way. Firstly, these compounds can be formed in the body by metabolizing the nitrite and nitrate found naturally or as additive in the food. Secondly, nitrite added to increase the microbiological resistance of meat, fish and cheese, can react with amines found naturally in the food to form nitrosamines. The way the food is cooked is also important for the formation of N-nitroso compounds; applied heat and cooking time are also important. N-nitroso compounds are formed more, when the nitrite cured meats are fried. Based on epidemiological studies, major cause (60 %) for human cancer is ascribed to the diet. In order to reduce the diet related cancers, the amount of N-nitroso compounds in the food should be carefully controlled and reduced. Similarly, the amount of nitrite and nitrates in the food should also be reduced. Awareness of public and manufacturers should be rised about the use of antioxidants like ascorbic acid (vitamin C) and alfa-tocopherol (vitamin E) which are known to inhibit the formation of N-nitroso compounds in the food or body. It should also be recommended to add these antioxidants as additive or consume them in the diet.

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