Some considerations with regard to the first results about volatile nitrosamine contents in some Cuban foods.

The volatile nitrosamine contents in some samples of Cuban beer and canned meat products are reported. Only dimethylnitrosamine in very low concentrations was detected. The significance of these results and the relative necessity to extend research works in this field are discussed.

Mutagenicity of N-nitrosomorpholine biosynthesized from morpholine in the presence of nitrate and its inhibition by ascorbic acid.

N-nitrosomorpholine biosynthesis and inhibition in mice treated with nitrate, morpholine and ascorbic acid, was studied by means of the mutagenic activity in urine samples. The preincubation method was used and Salmonella typhimurium TA 1535 was the test strain. The results suggest that N-nitrosomorpholine biosynthesis was carried out when the animals were fed high doses of nitrate, however ascorbic acid was an inhibitor of this process.

Estimation of the daily intake of cadmium which may be consumed by students 12-17 years old in secondary schools in the city of Havana.

In the present article we offer information regarding the estimated amounts of cadmium which may be consumed by 12,000 students 12 to 17 years old, who attend boarding secondary schools. The method of analysis used to determine cadmium is that reported by the Association of Official Analytical Chemists using atomic absorption spectrometry with air-acetylene flame. The estimated quantities of cadmium which these students may consume according to the offered foods are smaller than those recommended as provisional tolerable weekly intake by the Joint FAO/WHO Expert Committee on Food Additives.

Nitrate as a precursor of the in-vivo formation of N-nitrosomorpholine in the stomach of guinea-pigs.

Reduction of nitrates to nitrites and formation of the carcinogen N-nitrosomorpholine (NMOR) was investigated in the stomach of guinea-pigs. A semisynthetic diet with nitrate plus morpholine was administered intragastrically after a 24-h fast; after treatment, the animals were killed and stomach nitrite contents were determined 6, 12, 18, 24 and 30 min after the treatment using a colorimetric method. NMOR content was determined 18 min after treatment with nitrate plus morpholine using gas chromatography-thermal energy analysis. Reduction of nitrates to nitrites in the stomach was observed that was sufficient to synthesize NMOR in guinea-pigs under the conditions of this experiment.

A new method for the determination of saccharin based on thin-layer chromatography and spectrophotometry.

Saccharin is extracted from the acidified liquid food with chloroform. This solvent is evaporated; the residue is dissolved in ethyl acetate and applied on a silica gel GF254 plate. After chromatographic separation, the saccharin band is scraped off and extracted with 1% sodium carbonate solution. After centrifugation, absorbances at 235 and 244 nm are measured, and the difference A235-A244 is obtained. Standards similarly treated permit to get a calibrating plot and calculate the amount of saccharin in the sample. The method has good precision (C.V. 6%) and accuracy (91.2% recovery).

Effect of ascorbic acid on the hepatotoxicity due to the daily intake of nitrate, nitrite and dimethylamine.

It is known that nitrates, nitrites and dimethylamine may react in the gastro-intestinal tract synthesizing the powerful hepatotoxic and carcinogenic dimethylnitrosamine. The purpose of this study was to investigate hepatotoxicity due to the daily intake of nitrates and nitrites administered to rats during 14 weeks together with dimethylamine in drinking water, and to evaluate the protecting effect of ascorbic acid against the hepatotoxicity of the presumably endogenous formed dimethylnitrosamine. The toxicity criteria studied were weight of liver (absolute and relative), free and total bilirubin, alkaline phosphatase and pyruvic glutamic transaminase, all in the form of serum, and histopathologic tests of the liver. The results gave evidence of hepatotoxicity induced by the intake of nitrate, nitrite and dimethylamine all together, and not through the only intake of nitrate or nitrite or of amine. Daily doses of ascorbic acid [(211 +/- 40) and (18 +/- 4) mg/kg] seemed to hinder hepatotoxicity according to the criteria under investigation.

Estimation of the daily intake of nitrates and nitrites which may be consumed by students 12-17 years old in secondary schools in the city of Havana.

In the present article we offer informations regarding the estimated amounts of nitrates and nitrites which may be consumed by 12,000 students 12 to 17 years old, who attend boarding schools. The method of analysis used to determine nitrates and nitrites is that reported by the Joint FAO/WHO Expert Committee using a cadmium reducing column. The estimated quantities of nitrates and nitrites which these students may consume according to their food intake are smaller than those recommended as admissible daily intake by the Joint FAO/WHO Expert Committee on Food Additives.

Tyramine content of some Cuban cheeses.

The tyramine content of 8 types of cheeses made in Cuba were determined. Values obtained ranged from 0-425 micrograms/g. Highest results were found in Camembert-type cheese and lowest ones in Salami (processed type) cheese. It may be concluded that patients taking monoamine-oxidase inhibiting drugs should better not eat cheese, except processed or short-maturing types.

The effect of wheat bran on the excretion of cadmium in rats.

The influence of wheat bran as a source of dietary fibre on the excretion of ingested cadmium from diet was studied. The cadmium contents in the diets, faeces, urine, liver, kidney and spleen were determined, as well as the weight gains, the relative weights of the cited organs, and the levels of alkaline phosphatase in serum. No evidence is provided that an increasing portion of wheat bran in the diets induced an increase in cadmium excretion. Changes in the studied toxicity parameters were not found.

Estimation of the daily intake of nitrates and nitrites which children one to six years old, who attend State Nurseries in the City of Havanna, may consume.

The knowledge of the amounts of nitrates and nitrites consumed by the child population is of great importance due to three fundamental aspects: Reduction of nitrates to nitrites. Relation of these to methemoglobinemia. Carcinogenicity of the N-nitroso compounds, of which nitrites are the precursors. In the present article information is given as to the estimated amounts of nitrates and nitrites, which about 10 000 children between one and six years of age, who attend State Nurseries in the City of Havanna, may consume through the daily intake of food, milk and water offered by the Centralized Kitchen "Cuba-Finland Friendship". The method of analysis used to determine nitrates and nitrites is that reported by the Mixed Committee FAO/OMS in 1976, using a reducing column containing cadmium described by FOLLET et al. in 1963. The statistical method employed is the t-Test of the comparison of media. Estimated quantities of nitrates and nitrites, which these children may consume according to the offer of food, milk and water they receive, are: 25.6 mg of NaNO3 and 1.04 mg of NaNO2 for children one to three years of age, and 36.1 mg of NaNO3 and 1.48 mg of NaNO2 for children four to six. These values lie under those recommended as admissible daily intake reported by the Mixed Committee FAO/OMS. Therefore, there does not seem to exist a risk to health through consumption of nitrates and nitrites by the population under investigation.