Nitrate - Danger of fertilizer abuse

Using too much fertilizer, especially nitrogen fertilizer in cultivation leads to excess nitrate (NO ₃ ) and endangering consumer health, scientists warn.

Vietnam has about 26 million hectares of agricultural land with an annual demand of about 10 million tons of fertilizer, of which nearly 20% is nitrogenous. In order to improve crop productivity, farmers have increased fertilizer by 2-3 times, even 5-7 times compared to demand, leading to excess nitrate in fruits and vegetables.

Meanwhile, the survey results of the United Nations Food and Agriculture Organization show that plants only use about 40-50% of the fertilizer, the rest are washed away or exist on plant parts. .

According to Dr. Nguyen Kim Van, the Science and Technology Association for Plant Protection, due to wasteful practices and dumping in the use of chemical nitrogen causing excess nitrate and when exceeding the threshold, it will turn into nitrite which is harmful to children. people.

On each pole, farmers are misusing fertilizer to increase production without knowing how harmful it is to their health.(Photo: Nguyen Huan).

Nitrates are one of four factors that make vegetables unsafe , along with heavy metals , pesticides and microorganisms . When the amount of this substance exceeds the safety threshold, they are considered toxic, adversely affecting the health of users, causing many dangerous diseases. Nitrate was first discovered as a residual toxic substance in agricultural products, harming human health in 1945.

"Although nitrate is not toxic to plants, if the plant is used by humans, especially the leaf parts, nitrate reduces the nitrite in the digestive process, becoming a poison. Nitrite is easy to react with amine to form nitrosamin. , a cause of stomach cancer, " said Professor Nguyen Lan Dung, deputy chairman of the Council for Environmental Education Science Advisory of the Vietnam Fatherland Front Central Committee.

Professor said that in the human body nitrate quickly accumulates, losing the ability to transport oxygen in the blood, lowering blood pressure, and in high concentrations can also indirectly affect reproductive health, increase risk of miscarriage.

The maximum allowable limit of nitrate (NO ₃ ) content in some fresh vegetable products (mg / kg) according to Decision No. 867/1998 of the Ministry of Health.

To limit nitrates in crop products, consumers say it cannot be cleaned by washing, peeling or washing, because nitrates have been absorbed into plant cells so there is only a way to detect residuals. the amount exceeding the allowed threshold to not use or reduce the amount to avoid harm to the body.

Dr. Nguyen Kim Van said that the optimal method is that farmers should limit chemical fertilizers but use green manure, properly fertilize the demand for plants. According to the document of safe vegetable growing process of the Research Institute of Vegetables and Fruits, the demand for nitrogen fertilizer of pickles is 0.5 kg / rod, vegetables 0.5-1kg / rod .

According to some other experts, should not choose vegetables with green color, when buying fruits and vegetables to wash, salt soaked.