Dietary intakes of nitrate, nitrite and NDMA in the Finnish Mobile Clinic Health Examination Survey.

Concern about potential health hazards of nitrate, nitrite and N-nitroso compounds necessitates calculations of exposures to these compounds and their distribution in normal populations. This study describes dietary intake of nitrate (NO3-), nitrite (NO2-) and N-nitrosodimethylamine (NDMA) among 5304 adult men and 4750 women, who participated in the Finnish Mobile Clinic Health Examination Survey in 1967-72. Food consumption data for each individual over the preceding year were collected by a dietary history interview. Intakes of nitrate, nitrite and NDMA from vegetables, fruits, cheese, meat and fish products were calculated using available values mainly derived from Finland and other countries in northern Europe. Nitrate and nitrite from drinking water were not included in the study. Mean daily dietary intake of nitrate was 77 mg, of nitrite 5.3 mg, and of NDMA 0.05 microgram respectively. Intake of NDMA from beer, estimated in a part of the study population, was 0.07 microgram per day. More than 90% of dietary nitrate was derived from vegetables, including potatoes. Nitrite was mainly provided by cured meat products. Cured meat products and smoked and salted fish were important food sources of NDMA. The total daily intake of nitrate was similar in men and women, whereas intakes of nitrite and NDMA were higher in men than in women. The diet of farmers was characterized by lower amounts of nitrate, nitrite and NDMA, whereas white collar workers and those employed in industry had higher intakes. Current smokers were exposed to higher dietary intakes of nitrate, nitrite and NDMA than non-smokers. Intakes of dietary nitrate, nitrite and NDMA estimated on an individual level are suggested to be useful in evaluating the health effects of these compounds in epidemiological studies.