Nitrate, nitrite, and N-nitroso compounds in Finnish foods and the estimation of the dietary intakes

An estimate of the dietary intakes of nitrite, nitrate and N-nitroso compounds is presented, based on the analytical data supplied by the Finnish Food Quality Control. Figures on the food consumption of the Finnish population, taken from a national dietary survey, and food consumption of 1768 children and adolescents over a 48-h recall period were used. The mean daily dietary nitrate intakes were estimated to be about 55 mg for the total population and for children and adolescents. The mean nitrite intakes were 1.88 mg for the total population and 1.07 mg for children and adolescents. The intake of N-nitroso compounds (NDMA) was estimated to be 0.08 micrograms for the total population and 0.02 micrograms for children. Nitrates were found to originate mainly from vegetables (80%), nitrites from meat products (97%) and nitrosamines mostly from fish products and beer. A comparison of the estimate of dietary intake of with ADI values indicated that the nitrite intake of the total population was 23% and by children 39% of ADI. The average weight was approximately 60 kg for adults and 20 kg for children. When measured average weight (39 kg) was used, and the nitrite intake was found to be 28% of ADI. Nitrate intakes from food additives were 2.5% and 1.4% of the ADI value, respectively. When the total nitrate intake from various food sources was compared with the ADI (which is given only for food additives), the estimated nitrate intake of the total population was 25% and that of children 28% of the ADI value.     

Daily intakes of nitrate and nitrite in middle-aged men by the duplicate portion method

Daily intakes of nitrate and nitrite of middle-aged men (30-59 years of age, n = 100) in Hiroshima Prefecture were estimated directly by the duplicate portion method. The daily intake of nitrate was 190.8 +/- 128.5 mg. The daily intake of nitrate/kg body weight was 2.87 +/- 2.00 mg, which is about 78% of the acceptable daily intake (ADI). The daily intake of nitrate tended to increase with increasing age. The daily intake of nitrite was 3.837 +/- 3.647 mg. The daily intake of nitrite/kg body weight was 0.057 +/- 0.050 mg, which is about 95% of the ADI. In the case of nitrite, there was no age-related difference. The proportions of men, whose daily intakes of nitrate and nitrite were above the ADI, were 27% and 34%, respectively. The proportion of men above the ADI of both nitrate and nitrite was 10%.     

Survey of the daily intake of nitrate and nitrite in school children by the duplicate portion method

The daily intake of nitrate and nitrite in school children (n = 100) in Hiroshima Prefecture was estimated directly by the duplicate portion method. The daily intake of nitrate was 68.42 +/- 77.49 mg. The daily intake of nitrate/kg body weight was 2.06 +/- 2.24 mg, which is about 56% of the acceptable daily intake (ADI). The daily intake of nitrite was 0.953 +/- 0.869 mg. The daily intake of nitrite/kg body weight was 0.027 +/- 0.021 mg, which is about 45% of the ADI. The daily intake of nitrite/kg body weight was significantly different between the obese group and the non-obese group in boys (p < 0.05, Mann-Whitney U-test). The rates of children whose daily intakes of nitrate and nitrite were above the ADI were 16% and 7%, respectively.     

Average daily nitrate and nitrite intake in the Belgian population older than 15 years

The aim of this study was to assess the dietary intake of nitrate and nitrite in Belgium. The nitrate content of processed vegetables, cheeses and meat products was analysed. These data were completed by data from non-targeted official control and from the literature. In addition, the nitrite content of meat products was measured. Concentration data for nitrate and nitrite were linked to food consumption data of the Belgian Food Consumption Survey. This study included 3245 respondents, aged 15 years and older. Food intakes were estimated by a repeated 24-h recall using EPIC-SOFT. Only respondents with two completed 24-h recalls (n=3083) were included in the analysis. For the intake assessment, average concentration data and individual consumption data were combined. Usual intake of nitrate/nitrite was calculated using the Nusser method. The mean usual daily intake of nitrate was 1.38 mg kg(-1) bodyweight (bw) day(-1) and the usual daily intake at the 97.5 percentile was 2.76 mg kg(-1) bw day(-1). Exposure of the Belgian population to nitrate at a mean intake corresponded to 38% of the ADI (while 76% at the 97.5 percentile). For the average consumer, half of the intake was derived from vegetables (especially lettuce) and 20% from water and water-based drinks. The average daily intake of nitrate and nitrite from cheese and meat products was low (0.2% and 6% of the ADI at average intake, respectively). Scenario analyses with a higher consumption of vegetables or a higher nitrate concentration in tap water showed a significant higher intake of nitrate. Whether this is beneficial or harmful must be further assessed.     

The oral nitrate and nitrite intake in The Netherlands: evaluation of the results obtained by HPIC analysis of duplicate 24-hour diet samples collected in 1994.

In spring and autumn of 1994 duplicates of 24-h diets were collected from 123 respondents. One of the goals of this study was to determine the amount of nitrite and nitrate in the duplicates of 24-h diets to establish the oral daily intake of these analytes. For this purpose an HPIC/UV method for the determination of nitrate and nitrite in duplicate diets was developed and validated. The sample preparation procedure was derived from the in-house method used for the determination of nitrate and nitrite in human blood plasma. The sample is diluted with water, deproteinized with Carrez reagent, followed by chromatographic clean-up on an SPE C18-column. Both the nitrate and the nitrite results are quantitative. The recovery for nitrite was on average 104% (n = 21, spiking levels: 0.84-95 mg/kg) and for nitrate on average 103% (N = 21, spiking levels: 1.8-404 mg/kg). Samples of duplicates of 24-h diets were analysed according to the method developed. The median intake of nitrite calculated from the samples collected in spring 1994 was 0.6 mg/person day (range < 0.1-6.1 mg/person/day). For the samples collected in autumn 1994 these figures were < 0.2 mg/person/day (range < 0.1-16 mg/person/day). The mean intake of nitrate was 73 mg/person/day (range 7-322 mg/person/day) in spring 1994 and 87 mg/person/day (range 1-310 mg/person/day) in autumn 1994. The overall mean intake of nitrate in 1994 was 80 mg/person/day. The daily intake for nitrate was higher than that found in the duplicate diet study carried out in 1984/1985, when an average daily intake of 52 mg/person was measured. The intake of nitrite was also higher than found in the duplicate diets collected in 1984/1985. The findings of the study are discussed in the context of the ADI for nitrate and nitrite as well as the outcome of other recent European intake studies.     

Estimated dietary intake of nitrite and nitrate in Swedish children

This study examines the intake of nitrate and nitrite in Swedish children. Daily intake estimates were based on a nationwide food consumption survey (4-day food diary) and nitrite/nitrate content in various foodstuffs. The mean intake of nitrite from cured meat among 2259 children studied was 0.013, 0.010 and 0.007 mg kg(-1) body weight day(-1) in age groups 4, 8-9 and 11-12 years, respectively. Among these age groups, three individuals (0.1% of the studied children) exceeded the acceptable daily intake (ADI) of 0.07 mg nitrite kg(-1) body weight day(-1). The mean intake of nitrate from vegetables, fruit, cured meat and water was 0.84, 0.68 and 0.45 mg kg(-1) body weight day(-1) for children aged 4, 8-9 and 11-12 years, respectively. No individual exceeded the ADI of 3.7 mg nitrate kg(-1) body weight day(-1). However, when the total nitrite intake was estimated, including an estimated 5% endogenous conversion of nitrate to nitrite, approximately 12% of the 4-year-old children exceeded the nitrite ADI. Thus, the intake of nitrite in Swedish children may be a concern for young age groups when endogenous nitrite conversion is included in the intake estimates.     

Assessment of dietary exposure of nitrate and nitrite in France

The aim of this study was to assess the dietary exposure of nitrate and nitrite in France. A total of 13, 657 concentration levels of nitrate and nitrite measured in food, representing 138 and 109 food items, respectively, and coming from French monitoring programmes between 2000 and 2006, were used. Depending on the non-detected and non-quantified analysis treatment, lower and upper concentration mean estimates were calculated for each food item. These were combined with consumption data derived from 1474 adults and 1018 children from the French national individual consumption survey (INCA1), conducted in 1999 and based on a 7-day food record diary. A total of 18% of spinaches, 6% of salads, 10% of cheeses, 8% of meat products and 6% of industrial meat products exceeded the European nitrate maximum level or maximum residual level. A total of 0.4% of industrial meat products and 0.2% of meat products exceeded their European nitrite maximum level or maximum residual level. Nitrate dietary exposure averaged 40% of the acceptable daily intake (ADI; 3.7 mg kg(-1) body weight day(-1)) for adults and 51 - 54% of the ADI for children with the major contributors being, for adults and children, respectively, vegetables (24 and 27% of ADI), potatoes (5 and 11% of ADI), and water (5 and 5% of ADI). The individual nitrate dietary intake of 1.4% (confidence interval (CI(95th)) [0.8; 2.0]) to 1.5% (CI(95th) [0.9; 2.1]) of adults and 7.9% (CI(95th) [6.2; 9.6]) to 8.4% (CI(95th) [6.7; 10.1]) of children were higher than the ADI. Nitrite dietary exposure averaged 33-67% of the ADI (0.06 mg kg(-1) body weight day(-1)) for adults and 67-133% of the ADI for children, with contributions of additive food vectors at 33% of ADI for adults and 50-67% of ADI for children. The individual nitrite dietary intake of 0.7% (CI(95th) [0.3; 1.1]) to 16.4% (CI(95th) [14.5; 18.3]) of adults and 10.5% (CI(95th) [8.6; 12.4]) to 66.2% (CI(95th) [63.3; 69.1]) of children were higher than the ADI.     

Assessment of dietary exposure of nitrate and nitrite in France.

The aim of this study was to assess the dietary exposure of nitrate and nitrite in France. A total of 13, 657 concentration levels of nitrate and nitrite measured in food, representing 138 and 109 food items, respectively, and coming from French monitoring programmes between 2000 and 2006, were used. Depending on the non-detected and non-quantified analysis treatment, lower and upper concentration mean estimates were calculated for each food item. These were combined with consumption data derived from 1474 adults and 1018 children from the French national individual consumption survey (INCA1), conducted in 1999 and based on a 7-day food record diary. A total of 18% of spinaches, 6% of salads, 10% of cheeses, 8% of meat products and 6% of industrial meat products exceeded the European nitrate maximum level or maximum residual level. A total of 0.4% of industrial meat products and 0.2% of meat products exceeded their European nitrite maximum level or maximum residual level. Nitrate dietary exposure averaged 40% of the acceptable daily intake (ADI; 3.7 mg kg(-1) body weight day(-1)) for adults and 51 - 54% of the ADI for children with the major contributors being, for adults and children, respectively, vegetables (24 and 27% of ADI), potatoes (5 and 11% of ADI), and water (5 and 5% of ADI). The individual nitrate dietary intake of 1.4% (confidence interval (CI(95th)) [0.8; 2.0]) to 1.5% (CI(95th) [0.9; 2.1]) of adults and 7.9% (CI(95th) [6.2; 9.6]) to 8.4% (CI(95th) [6.7; 10.1]) of children were higher than the ADI. Nitrite dietary exposure averaged 33-67% of the ADI (0.06 mg kg(-1) body weight day(-1)) for adults and 67-133% of the ADI for children, with contributions of additive food vectors at 33% of ADI for adults and 50-67% of ADI for children. The individual nitrite dietary intake of 0.7% (CI(95th) [0.3; 1.1]) to 16.4% (CI(95th) [14.5; 18.3]) of adults and 10.5% (CI(95th) [8.6; 12.4]) to 66.2% (CI(95th) [63.3; 69.1]) of children were higher than the ADI.     

Nitrate, nitrite, and N-nitroso compounds in Finnish foods and the estimation of the dietary intakes

Summary An estimate of the dietary intakes of nitrite, nitrate andN-nitroso compounds is presented, based on the analytical data supplied by the Finnish Food Quality Control. Figures on the food consumption of the Finnish population, taken from a national dietary survey, and food consumption of 1768 children and adolescents over a 48-h recall period were used. The mean daily dietary nitrate intakes were estimated to be about 55 mg for the total population and for children and adolescents. The mean nitrite intakes were 1.88 mg for the total population and 1.07 mg for children and adolescents. The intake ofN-nitroso compounds (NDMA) was estimated to be 0.08 g for the total population and 0.02 g for children. Nitrates were found to originate mainly from vegetables (80%), nitrites from meat products (97%) and nitrosamines mostly from fish products and beer. A comparison of the estimate of dietary intake of nitrite with ADI values indicated that the nitrite intake of the total population was 23% and by children 39% of ADI. The average weight was approximately 60 kg for adults and 20 kg for children. When measured average weight (39 kg) was used, and the nitrite intake was found to be 28% of ADI. Nitrate intakes from food additives were 2.5% and 1.4% of the ADI value, respectively. When the total nitrate intake from various food sources was compared with the ADI (which is given only for food additives), the estimated nitrate intake of the total population was 25% and that of children 28% of the ADI value.

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Nitrat, Nitrit und N-nitroso-Verbindungen in der finnischen Nahrung

Zusammenfassung Die Einnahme von Nitrat, Nitrit undN-Nitroso-Verbindungen stützt sich auf die analytischen Werte der finnischen Lebensmittelkontrolle. Für die Schätzung der Nahrungsaufnahme der finnischen Bevölkerung benutzte man Resultate einer nationalen Nahrungsforschung und eines 48-Stunden-Befundes für 1768 Kinder und Jugendliche. Die durchschnittliche tägliche Einnahme von Nitrat schätzte man auf ungefähr 55 mg für die ganze Bevölkerung. Die durchschnittliche Einnahme von Nitrit betrug 1,88 mg für die ganze Bevölkerung und 1,07 mg für Kinder und Jugendliche. Die Einnahme vonN-Nitroso-Verbindungen (NDMA) schätzte man auf 0,08 g für die ganze Bevölkerung und 0,02 g für Kinder. Die hauptsächliche Nahrungsquelle der Nitrate war Gemüse (80%) und bei den Nitriten die Fleischwaren (97%). Nitrosamine stammten hauptsächlich aus Fischwaren und aus Bier. Als man die geschätzte Einnahme von Nitrit mit den ADI-Werten verglich, ergab sich, daß die Einnahme von Nitrit 23% (ganze Bevölkerung) und 39% (Kinder) des ADI-Wertes war. Als durchschnittliches Körpergewicht nahm man 60 kg für Erwachsene und 20 kg für Kinder an. Wenn man den Wert des gemessenen durchschnittlichen Körpergewichts (39 kg) für Kinder benutzte, war die Einnahme von Nitrit 28% des ADI-Wertes. Die Einnahme von Nitrat in Zusatzstoffen war 2,5% und entsprechend 1,4% des ADI-Wertes. Die Einnahme von Nitrat in der Nahrung schätzte man auf 25% (ganze Bevölkerung) und auf 28% (Kinder) des ADI-Wertes (gegeben nur für Nitrat als Zusatzstoffe).

     

Estimation of inorganic food additive (nitrite,nitrate and sulfur dioxide), antioxidant (BHA and BHT), processing agent (propylene glycol) and sweetener (sodium saccharin) concentrations in foods and their daily intake based on official inspection results in Japan in fiscal year 1998

The mean concentration and daily intake of inorganic food additives (nitrite, nitrate, and sulfur dioxide), antioxidants (BHA and BHT), a processing agent (propylene glycol), and a sweetener (sodium saccharin) were estimated based on the results of an analysis of 34,489 food samples obtained in official inspections by 106 local governments in Japan in fiscal year 1998. The ratios of mean concentrations of these seven food additives to each allowable limit were 20.0%, 53.9%, 15.5%, 6.2%, 0.4%, 18.5%, and 5.7%, respectively. The daily intakes of these food additives estimated from their concentrations in foods and the daily consumption of foods were 0.205, 0.532, 4.31, 0.119, 0.109, 77.5, and 7.27 mg per person, respectively. These amounts were 6.8%, 0.3%, 12.3%, 0.5%, 0.7%, 6.2%, and 2.6% of the acceptable daily intake (ADI), respectively, when body weight was assumed to be 50 kg. No remarkable differences in the daily intakes of these seven food additives or the ratios to the ADI were observed compared with the results based on the official inspections in fiscal years 1994 and 1996.     

Estimated dietary intake of nitrite and nitrate in Swedish children

This study examines the intake of nitrate and nitrite in Swedish children. Daily intake estimates were based on a nationwide food consumption survey (4-day food diary) and nitrite/nitrate content in various foodstuffs. The mean intake of nitrite from cured meat among 2259 children studied was 0.013, 0.010 and 0.007?mg?kg^?1?body?weight?day^?1 in age groups 4, 8–9 and 11–12 years, respectively. Among these age groups, three individuals (0.1% of the studied children) exceeded the acceptable daily intake (ADI) of 0.07?mg?nitrite?kg^?1 body weight?day^?1. The mean intake of nitrate from vegetables, fruit, cured meat and water was 0.84, 0.68 and 0.45?mg?kg^?1 body weight?day^?1 for children aged 4, 8–9 and 11–12 years, respectively. No individual exceeded the ADI of 3.7?mg?nitrate?kg^?1 body weight?day^?1. However, when the total nitrite intake was estimated, including an estimated 5% endogenous conversion of nitrate to nitrite, approximately 12% of the 4-year-old children exceeded the nitrite ADI. Thus, the intake of nitrite in Swedish children may be a concern for young age groups when endogenous nitrite conversion is included in the intake estimates.     

Assessment of dietary exposure of nitrate and nitrite in France

The aim of this study was to assess the dietary exposure of nitrate and nitrite in France. A total of 13, 657 concentration levels of nitrate and nitrite measured in food, representing 138 and 109 food items, respectively, and coming from French monitoring programmes between 2000 and 2006, were used. Depending on the non-detected and non-quantified analysis treatment, lower and upper concentration mean estimates were calculated for each food item. These were combined with consumption data derived from 1474 adults and 1018 children from the French national individual consumption survey (INCA1), conducted in 1999 and based on a 7-day food record diary. A total of 18% of spinaches, 6% of salads, 10% of cheeses, 8% of meat products and 6% of industrial meat products exceeded the European nitrate maximum level or maximum residual level. A total of 0.4% of industrial meat products and 0.2% of meat products exceeded their European nitrite maximum level or maximum residual level. Nitrate dietary exposure averaged 40% of the acceptable daily intake (ADI; 3.7 mg kg^?1 body weight day^?1) for adults and 51???54% of the ADI for children with the major contributors being, for adults and children, respectively, vegetables (24 and 27% of ADI), potatoes (5 and 11% of ADI), and water (5 and 5% of ADI). The individual nitrate dietary intake of 1.4% (confidence interval (CI_95th) [0.8; 2.0]) to 1.5% (CI_95th [0.9; 2.1]) of adults and 7.9% (CI_95th [6.2; 9.6]) to 8.4% (CI_95th [6.7; 10.1]) of children were higher than the ADI. Nitrite dietary exposure averaged 33–67% of the ADI (0.06 mg kg^?1 body weight day^?1) for adults and 67–133% of the ADI for children, with contributions of additive food vectors at 33% of ADI for adults and 50–67% of ADI for children. The individual nitrite dietary intake of 0.7% (CI_95th [0.3; 1.1]) to 16.4% (CI_95th [14.5; 18.3]) of adults and 10.5% (CI_95th [8.6; 12.4]) to 66.2% (CI_95th [63.3; 69.1]) of children were higher than the ADI.     

Determination of dietary nitrite in patients with esophageal pre-cancerous lesion and normal people: a duplicate diet study

ABSTRACT

The goal of this study was to find the relationship between dietary nitrite and risk of esophageal cancer, and determine the amount of nitrite intake to establish the oral highest daily intake to prevent the occurrence of esophageal cancer. Duplicate portions of three-consecutive-day diets were collected from 100 patients with esophageal precancerous lesions and 100 controls. The average nitrite daily intakes for esophageal precancerous lesions and normal people were 15.72 mg/d and 11.11 mg/d. The median nitrite daily intakes for cases and controls were 8.76 mg/d and 5.33 mg/d. Positive association was observed between the risk of esophageal precancerous lesions and dietary nitrite intake (p = 0.035). An increased risk of esophageal precancerous lesions was observed for cases or controls in the highest intake quartile of nitrite (highest vs. lowest quartile odds ratio (OR) = 2.256, 95% confidence interval (CI): 1.012–5.026). These results suggest that dietary nitrite intake may influence the risk of esophageal cancer; populations with high incidence of esophageal cancer should take control of nitrite intake as one of the measures to prevent esophageal cancer.     

Exposure assessment of food preservatives (sulphites, benzoic and sorbic acid) in Austria

An exposure assessment was performed to estimate the potential intake of preservatives in the Austrian population. Food consumption data of different population groups, such as preschool children aged 3-6 years, female and male adults aged 19-65 years were used for calculation. Levels of the preservatives in food were derived from analyses conducted from January 2007 to August 2010. Dietary intakes of the preservatives were estimated and compared to the respective acceptable daily intakes (ADIs). In the average-intake scenario, assuming that consumers randomly consume food products that do or do not contain food additives, estimated dietary intakes of all studied preservatives are well below the ADI for all population groups. Sulphite exposure accounted for 34%, 84% and 89% of the ADI in preschool children, females and males, respectively. The mean estimated daily intake of benzoic acid was 32% (preschool children), 31% (males) and 36% (females) of the ADI. Sorbic acid intakes correspond to 7% of the ADI in preschool children and 6% of the ADI in adults. In the high-intake scenario assuming that consumers always consume food products that contain additives and considering a kind of brand loyalty of consumers, the ADI is exceeded for sulphites among adults (119 and 124%, respectively). Major contributors to the total intake of sulphites were wine and dried fruits for adults. Mean estimated dietary intakes of benzoic acid exceeded the ADI in all population groups, 135% in preschool children, 124% in females and 118% of the ADI in males, respectively. Dietary intakes of sorbic acid are well below the ADI, accounting for a maximum of 30% of the ADI in preschool children. The highest contributors to benzoic and sorbic acid exposure were fish and fish products mainly caused by high consumption data of this large food group, including also mayonnaise-containing fish salads. Other important sources of sorbic acid were bread, buns and toast bread and fruit and vegetable juices.     

Assessment of estimated daily intakes of benzoates for average and high consumers in Korea.

A study was performed to evaluate the estimated daily intakes (EDI) of benzoates for the average and high (90th percentile) consumers by age and sex categories in Korea. The estimation of daily intakes of benzoates was based on individual dietary intake data from the National Health and Nutrition Survey in 1998 and on the determination of benzoates in eight food categories. The EDI of benzoates for average consumers of different age groups ranged from 0.009 to 0.025 mg kg(-1) bw day(-1). For high consumers, the range of EDI of benzoates was 0.195-1.878 mg kg(-1) bw day(-1). The intakes represented 0.18-0.50% of the acceptable daily intake (ADI) of benzoates for average consumers and 3.9-37.6% of the ADI for high consumers. Foods that contributed most to the daily intakes of benzoates were mixed beverages and soy sauce in Korea.     

Dietary exposure of Hong Kong adults to nitrate and nitrite from vegetable intake

The aim of this study was to assess the dietary exposure of adults in Hong Kong to nitrate and nitrite from vegetables. If all vegetables consumed were raw, the dietary exposure to nitrate for average consumers was estimated to be 4.4?mg?kg^?1 body weight (bw)?day^?1 and, for high consumers, was estimated to be 13?mg?kg^?1?bw?day^?1, which is about 120 and 350% of acceptable daily intake (ADI), respectively. If all vegetables consumed were cooked, the dietary exposure to nitrate from vegetables for the average adult consumer was estimated to be 3.5?mg?kg^?1?bw?day^?1 and, for high consumer, was estimated to be 10?mg?kg^?1?bw?day^?1, which is about 95 and 270% of ADI, respectively. On the other hand, the dietary exposure to nitrite from vegetables for average and high consumers were well below the ADI.     

Nitrite and nitrate content in meat products and estimated intake in Denmark from 1998 to 2006

The content of nitrite and nitrate in cured meat products has been monitored in Denmark seven times between 1995 and 2006. The maximum permitted added amounts of sodium nitrite in Denmark (60 mg kg(-1) for most products up to 150 mg kg(-1) for special products) have not been exceeded, except for a few samples back in 2002. The intake, mean and intake distribution of sodium nitrite have been calculated from 1998 to 2006 with data from the Danish dietary survey conducted in 2000-02 on Danes from four to 75 years of age. The amounts used by industry have been relatively stable through the whole period with levels varying between 6 and 20 mg sodium nitrite kg(-1) with sausages, meat for open sandwiches and salami-type sausages being the greatest contributors. The mean intake of sodium nitrate was around 1 mg day(-1), which is very low compared with the total intake of 61 mg day(-1). The mean intake of sodium nitrite was 0.017 and 0.014, 0.009 and 0.008, and 0.007 and 0.003 mg kg(-1) body weight day(-1) for men and women in the age groups 4-5, 6-14 and 15-75 years, respectively, which was much lower than the acceptable daily intake (ADI) of 0.09 mg kg(-1) body weight day(-1). The 99th percentile for the group of 4-year-olds was 0.107 and 0.123 mg kg(-1) body weight day(-1) for boys and girls, respectively, and the 95th percentile was 0.057 and 0.073 mg kg(-1) body weight day(-1) for boys and girls, respectively, highest for the girls. With fewer than 100 boys and girls in the 4-5-year age group, only very few persons were responsible for the high intake. The conversion of nitrate to nitrite in the saliva and the degradation of nitrite during production and storage must also be considered when evaluating the intake of nitrite.     

Intake and risk assessment of nitrate and nitrite from New Zealand foods and drinking water

Exposure to excess nitrite is a potential health risk for humans. One hundred meat and processed foods and 100 vegetable samples purchased from New Zealand retail outlets were prepared as for consumption and analysed for nitrite and nitrate concentration using a standard, validated methodology. Nitrate concentrations ranged from less than the limit of detection (LOD = 5 mg kg^-1) in cheddar cheese and cream cheese-based dips to 3420 mg kg^-1 in lettuce. Nitrite was detected in half the processed foods and meats analysed (levels up to 119 mg kg^-1), but detected in only one vegetable sample above the LOD (broccoli at 27 mg kg^-1 nitrite). Concentration data were combined with 24 h dietary recall information to generate 4398 individual adult daily exposure scenarios for exogenous nitrite and nitrate including a contribution from water assessed from 1021 drinking water samples. The mean adult daily intake of exogenous nitrate and nitrite from food and water combined was 16 and 13% of the Acceptable Daily Intake (ADI), respectively, and therefore should not pose a health risk for the average consumer. A maximally exposed New Zealand adult is estimated to have an intake of up to seven times the ADI for nitrate. When the endogenous conversion of nitrate to nitrite is taken into account, approximately 10% of people with an average rate of conversion and half of all people with a high rate of conversion are estimated to exceed the ADI. Either the ADI is inappropriate and needs to be re-evaluated, or those individuals who have a high rate of conversion of nitrate to nitrite are at risk to adverse effects of nitrite exposure.     

Nitrates, nitrites and N-nitrosocompounds: a review of the occurrence in food and diet and the toxicological implications

Data on occurrence of nitrate, nitrite and N-nitrosocompounds in food and drinking water, and on total dietary intakes are reviewed. Metabolic, toxicological and epidemiological studies are surveyed and the implications with respect to safety evaluation are addressed. It is concluded that, on the basis of recent long-term animal studies and of clinical experience in man, the current Acceptable Daily Intake (ADI) allocated to nitrate by the Joint FAO/WHO Expert Committee on Food Additives of 0-5 mg/kg body weight/day (expressed as sodium nitrate) might be increased to 0-25 mg/kg body weight/day. Based on similar criteria, the ADI for nitrite would be 0-0.1 mg/kg body weight/day (expressed as sodium nitrite). In view of the known carcinogenicity of N-nitrosocompounds, exposure to these compounds in food should be minimized by appropriate technological means, such as lowering the nitrite concentration in preserved foods to the minimum required to ensure microbiological safety and use of inhibitors of nitrosation like alpha-tocopherol or ascorbic acid. Further work is needed to define the minimal levels of nitrite in foods needed to inhibit outgrowth of Clostridium botulinum and toxin production.     

Heavy metals in vegetables grown in The Netherlands and in domestic and imported fruits

The contents of cadmium, lead mercury, copper, manganese and zinc in 242 samples of 37 different species of domestic and imported fruits have been determined. Also contents of the same heavy metals, except mercury, have been determined in 205 samples of 7 species of domestic vegetables (lettuce, spinach, endive, beetroots, onions, celeriac and Swedish turnips). The median contents (in mg/kg fresh mass of the edible part) found for fruits are: Cd 0.002; Pb 0.017; Hg 0.002; Cu 0.61; Mn 0.52 and Zn 0.99. In the vegetables median levels have been found (mg/kg) of 0.009-0.073 for Cd, 0.01-0.03 for Pb, less than 0.2-0.3 for Cu, 0.69-1.41 for Mn and 0.95-5.5 for Zn. The contribution of fruits to the tolerable daily intakes of Cd, Pb and Hg is, for an average consumption pattern, less than 1%. On the other hand, the contribution to the recommended amounts of the essential elements Cu, Mn, and Zn is no more than 1%-3%. From the vegetables an average portion of spinach contains 19% and 2.6% of the tolerable daily amounts of Cd and Pb, respectively. For the other species of vegetables these figures are less than 5% for Cd (except for endive, 6.8%) and for lead less than 1%. Spinach contributes considerably to the need for Cu, Mn and Zn, in general more than 10% of the recommended daily amounts. The other species of vegetables contribute only from less than 1% to less than few percents.