Bengt-Göran Österdahl

Volatile nitrosamines in foods on the Swedish market and estimation of their daily intake

Foods on the Swedish market in 1980–1986 were analysed for volatile N‐nitrosamines using gas chromatography‐thermal energy analysis. Detectable levels were found in 474 of the 764 samples analysed. The average daily intake of volatile N‐nitrosamines was estimated to be 0.29 μg per person. Over 93% of the intake comes from meat and malt products.

Oxytetracycline residues in rainbow trout analysed by a rapid HPLC method

A rapid and sensitive HPLC method was developed for the determination of oxytetracycline in fish tissues (muscle and liver) based on a clean-up and concentration procedure on Sep-Pak C18. At a coastal fishfarm rainbow trout (Salmo gairdneri) suffering from Vibrio anguillarum were treated with 75 mg oxytetracycline per kg fish and day for ten days. Oxytetracycline residues above the limit of determination (0.005 micrograms/g) were found in fish 82 days after treatment. The recoveries from spiked tissues were about 60% and 70% for muscle and liver, respectively.

Pressurised fluid extraction (PFE) as an alternative general method for the determination of pesticide residues in rape seed.

A pressurised fluid extraction (PFE) multi-method has been developed for the determination of pesticide residues in rape seed. The method was validated for 25 different pesticides and metabolites. The reliability and efficiency of PFE for extracting pesticide residues from rape seed was investigated. The traditional extraction solvent, hexane saturated with acetonitrile, was used at elevated temperature and pressure. With increased temperature, the extraction kinetics were improved but at the same time more co-extractives were obtained in the form of lipids. When 1 g of rape seed was extracted at temperatures from 60 degrees C to 150 degrees C, the lipid content extracted was found to be as high as 17-26%. An additional clean-up step was therefore required and lipid co-extractives were effectively removed by gel permeation chromatography. The interpretation of the chromatograms and the quantification of the results were satisfactorily improved by the removal of interfering lipids. The developed method was used to extract vinclozolin and iprodione from incurred samples, resulting in a concentration in accordance with the results using conventional liquid-liquid extraction (LLE) between hexane and acetonitrile and also supercritical fluid extraction (SFE) using carbon dioxide. The results of the present study suggest that PEE is a good alternative extraction technique for the determination of pesticide residues in oil seed. Despite the necessity for a lipid-removal clean-up step, the PFE technique facilitated the extraction process by faster extractions and the possibility of automated analysis.

Tobacco‐specific N‐nitrosamines in the saliva of habitual male snuff dippers

Saliva was collected every ten minutes from habitual male snuff dippers and analysed for tobacco-specific N-nitrosamines (TSNA). Detectable levels of at least two TSNA were found in all samples collected between 10 and 30 minutes after the snuff had been placed in the mouth. Total concentrations of TSNA up to 241 ng/g were found in the saliva. Trace levels of TSNA were still found in the saliva 20 minutes after the snuff had been removed.

Volatile nitrosamines in microwave-cooked bacon.

Bacon was analysed for volatile nitrosamines after microwave cooking, and the results were compared with those obtained after frying bacon in a pan. Microwave cooking gave statistically significantly lower levels of all three volatile nitrosamines detected in the bacon. NPYR was found in all 20 samples fried in a pan, but in only five microwave-cooked samples. The average volatile nitrosamine levels (micrograms/kg) in microwave-cooked bacon and pan-fried bacon were: NDMA, 0.3 and 1.2; NPIP, 0.04 and 0.2; NPYR, 0.1 and 4.5.

Excretion of N-mononitrosopiperazine in urine in workers manufacturing piperazine

SummaryPiperazine has been shown to nitrosate in vivo to N-mononitrosopiperazine (MNPZ) by oral intake. Urine from workers exposed to piperazine in a chemical plant was analysed for nitrosamines by gas chromatography-thermal energy analysis. In five out of 11 exposed cases, MNPZ excretion in urine was 0.3 to 4.7 μg/24 h (during and after a work shift). In four cases, MNPZ was detected in some urine samples, and in two cases MNPZ was not detected (< 0.1 ng/ml). The individual excretion was strongly dependent on piperazine exposure, which ranged from 0.06 to 1.7 mg/m3 (time-weighted average; Spearmans rank correlation 0.78, P = 0.01). The MNPZ excretion showed no significant correlation with nitrite or nitrate in saliva (both: r = 0.50, P = 0.10).

Effect of ascorbic acid on N-nitrosoproline excretion in the urine of lacto-vegetarians and subjects on a free-choice diet.

The amounts of N-nitrosoproline (NPRO) excreted in the urine of lacto-vegetarians and subjects eating a free-choice diet were determined. The study was carried out during four consecutive weeks and specified extra amounts of ascorbic acid were ingested daily during three of them. The average amount of NPRO excreted in the urine of the lacto-vegetarians (1.33 micrograms/24 h) was slightly smaller than that in the urine of the individuals eating a free-choice diet (2.13 micrograms/24 h). Intake of as little as 3 x 20 mg of extra ascorbic acid per day reduced the NPRO excretion. Intake of 3 x 1000 mg of ascorbic acid resulted in a statistically significant decrease in NPRO excretion in the urine.

Levamisole residues in milk from a herd of cows suffering from lungworms.

A single intramuscular dose of 7 mg levamisole hydrochloride per kg body weight was administered to a herd of 42 milking cows suffering from lungworms. Levamisole was rapidly excreted in the milk, the peak concentration being found 1 h after administration. The half-life of levamisole in milk was about 5 h. Levamisole levels were below the limit of determination (0.04 microgram/ml) in all milk samples 29 h after treatment.

Effect of water on nitrosamine formation in fried bacon.

Bacon was soaked in water before frying and the effect on the formation of N-nitrosodimethylamine and N-nitrosopyrrolidine was studied. Soaking for 5 minutes reduced N-nitrosopyrrolidine levels by as much as 52%, but had little effect on N-nitrosodimethylamine levels. Longer soaking periods, up to 17 hours, gave the same results.