Exposure of children and adults to nitrites and nitrates

Evira assessed the extent of risks from exposures of Finnish children and adults to nitrates and nitrites originating from natural sources and via the use of additives. The investigation was aimed at providing new information on the extent of exposure of the population in Finland to these compounds.

Another aim of the project was to define the contents of nitrates and nitrites in vegetables (from natural sources), charcuteries and cheeses (use of additives) commonly consumed in Finland. In assessing these risks, actual food consumption data (from FinDIET 2007 and DIPP projects) and concentration results from laboratory analyses were used.

Long-term exposure of Finns to nitrates and nitrites was estimated probabilistically using the Monte Carlo method, based on levels measured in foods and on individual food consumption data of children of 1, 3 and 6 years as well as that of adults of 25 to 74 years.

Most of the intake of nitrates (NO3- or nitrate ion) comes from natural sources such as vegetables, fruit and water. The intake is highest for those who favour vegetables with a high nitrate content, such as salads, rocket, spinach and red beet. People who eat a lot of vegetables with a high nitrate content may exceed the acceptable daily intake (ADI) for nitrates, which is 3.7 mg of nitrate ions per kg of body weight per day. Temporarily exceeding the ADI does not in itself translate into a health risk, because ADIs are determined using wide safety margins.

Preparation of vegetables – washing and peeling – lowers nitrate content, as does cooking in most cases. Nitrate levels depend on the type of fruit or vegetable and the climate conditions in the place of cultivation. It is possible to reduce levels slightly through good agricultural practice.

It is generally considered that the nutrition benefits of eating fruit and vegetables exceed any disadvantages that may be caused by nitrates. In 2008, the European Food Safety Authority (EFSA) estimated that if one eats fruit and vegetables according to the recommendations, the health benefits will be greater than any adverse impact possibly caused by exceeding the ADI for nitrates on a temporary basis.

Nitrate levels in household water are generally low, but locally higher levels may occasionally occur. Nitrates used as additives in meat products, cheeses and pickled herring contribute only a very small part of the total exposure.

The most important source of nitrite exposure (NO2- or nitrite ion) for Finns is sausages, particularly cooking sausages, because they are used often and in large quantities. Nitrates and nitrites are used as food additives to prevent the growth of bacteria that cause food poisoning. The heat treatments usually used in the preparation of Finnish processed meat products are not sufficient to destroy the spores of the Clostridium botulinum bacteria that cause botulism.

Nitrite use is necessary to ensure consumer safety especially in products with a low salt content and a long shelf life. If nitrite levels were to be reduced from the present, hygiene requirements and cold chain management would have to be tightened. Nitrites also affect the colour and taste of sausages. The use of additives is governed by decree, specifying maximum levels and products in which they may be used.

The level of nitrites in household water is governed by the Household Water Decree. However, household water contributes substantially less to consumers’ exposure to nitrites than food additives.

In the study, nitrite levels were measured at the probable average time of consumption, about one week before the sell-by date. It was estimated that exposure to nitrites from food additives for children aged 1 remained below the ADI, which is 0.07 mg of nitrite ions per kg of body weight per day.

However, in the research material it was found that exposure to nitrites from food additives and household water exceeded the ADI for about 0.2% of adults, about 14% of children aged 3 and 11% of children aged 6 in Finland. Long-term exposure consistently exceeding the ADI translates into a potential health risk, the likelihood of which increases as the exposure increases.

High levels of nitrates and nitrites may inhibit oxygen transfer in the body. Exposure to nitrites is also suspected of elevating the risk of diabetes, coronary disease and cancer, but the research findings so far have been contradictory, and no causal link between exposure to nitrites and these conditions has been proven. In the risk assessment conducted by Evira, the risk was assessed on the basis of acceptable daily intake (ADI), regarding the values of which there is a general scientific consensus. The safety and ADI of nitrates and nitrites used as food additives will be re-evaluated in the EU by the end of 2015.

Key words

Nitrate, nitrite, risk assessment, food, exposure, intake, ADI, vegetables, sausage, food additives

Project publications

Suomi, J., Ranta, J., Tuominen, P., Putkonen, T., Bäckman, C., Ovaskainen, M.-L. Suvi M. Virtanen, Savela, K. Quantitative risk assessment on the dietary exposure of Finnish children and adults to nitrite. Food Additives & Contaminants: Part A, 33:1, 41–53.

Time schedule

2009 - 2013

Project funding

Evira

Further information

Johanna Suomi
johanna.suomi@foodauthority.fi