Prevention of poisoning. Nitrite in ham and sausage has an acute toxicity, so its content determination is to prevent poisoning, adult poisoning amount of 0.2g-0.5g, lethal amount of 1g ~ 2g. Nitrite in the right conditions can generate nitrite compounds, it is in the body and protein-containing food in the synthesis of secondary amines in the nitrosamines, as a strong carcinogen, the human body has a great harm.