Monitoring of lead, nitrate, and nitrite concentrations in the raw milk; a case of study (livestock of the Lenjan region, Isfahan Province)

Milk and dairy products, due to their high nutritional value and consumption by all ages, are an important part of the human diet in many parts of the world. Nitrate and heavy metals contamination of milk is a danger to humans that is much more common in childhood. The Lenjan county in the southwest of Isfahan province and different industries, such as Esfahan Steel Company and Mobarakeh Steel Company, are located around the region. In addition, because of the intensive agricultural activities in this region, dairy products, including raw milk, could be exposed to nitrate and heavy metals pollution. The objective of this study is to investigate the concentration of lead, nitrate, and nitrite in the raw milk of livestock in the Lenjan region. Raw milk sampling was performed in polyethylene containers from 30 farms including industrial, semi-industrial, and traditional units situated in the different parts of the county. Furthermore, eight samples of raw and pasteurized milk from a dairy processing company in the region were collected in four different working days. The vanadium trichloride reduction and graphite furnace atomic absorption methods were used to measure the nitrate and lead concentrations of the samples, respectively. The results demonstrated that the concentration range of nitrate was 0-12.6 with a mean of 1.41 mg/kg; nitrite was 0-3.3 with a mean of 0.11 mg/kg; and lead was 0.006-0.387 with a mean of 0.03 mg/kg. Nitrite and nitrate levels of the samples were less than the standard of Codex (1 and 10 mg/kg, respectively). Moreover, the amount of lead in 16.7% of the samples was higher than the world standard (0.002 mg/kg). The risk assessment of lead and nitrate for humans through the consumption of raw milk was in the safety range. Risk factors (THQ) for lead, nitrate, and nitrite were 0.14, 0.01, and 0.0, respectively. However, monitoring of various contaminants in dairy products in the areas, which are at high risk of contamination, seems to be necessary.