Volatile N-nitrosamines in selected Italian cheeses

Risk assessment of N-nitrosamines in food

EFSA was asked for a scientific opinion on the risks to public health related to the presence of N-nitrosamines (N-NAs) in food. The risk assessment was confined to those 10 carcinogenic N-NAs occurring in food (TCNAs), i.e. NDMA, NMEA, NDEA, NDPA, NDBA, NMA, NSAR, NMOR, NPIP and NPYR. N-NAs are genotoxic and induce liver tumours in rodents. The in vivo data available to derive potency factors are limited, and therefore, equal potency of TCNAs was assumed. The lower confidence limit of the benchmark dose at 10% (BMDL10) was 10 μg/kg body weight (bw) per day, derived from the incidence of rat liver tumours (benign and malignant) induced by NDEA and used in a margin of exposure (MOE) approach. Analytical results on the occurrence of N-NAs were extracted from the EFSA occurrence database (n = 2,817) and the literature (n = 4,003). Occurrence data were available for five food categories across TCNAs. Dietary exposure was assessed for two scenarios, excluding (scenario 1) and including (scenario 2) cooked unprocessed meat and fish. TCNAs exposure ranged from 0 to 208.9 ng/kg bw per day across surveys, age groups and scenarios. 'Meat and meat products' is the main food category contributing to TCNA exposure. MOEs ranged from 3,337 to 48 at the P95 exposure excluding some infant surveys with P95 exposure equal to zero. Two major uncertainties were (i) the high number of left censored data and (ii) the lack of data on important food categories. The CONTAM Panel concluded that the MOE for TCNAs at the P95 exposure is highly likely (98-100% certain) to be less than 10,000 for all age groups, which raises a health concern.

N-nitrosamines in Qingdao dried aquatic products and dietary risk assessment

N-nitrosamines are human carcinogens commonly present in dried aquatic products. A method of gas chromatography - mass spectrometry combined with steam distillation was developed for the determination of 9 N-nitrosamines in dried aquatic products in Qingdao, China, with which 300 samples of fish, squid, shrimp and sea cucumber collected from Qingdao were analysed. A health risk assessment was conducted based on determined levels of N-nitrosamines by using estimated daily intake and slope factors. Results showed that fish products was the category with the highest content of N-nitrosamines, whereas squid and shrimp products were the categories with the highest frequency of presence of N-nitrosamines. The average estimated cancer risk of N-nitrosamines in dried aquatic products in Qingdao ranged from 3.57 × 10^-8 to 3.53 × 10^-5. Nitrosodimethylamine, N-Nitrosodiethylamine and N-Nitrosodibutylamine could be considered to pose a potential cancer risk to residents in Qingdao.

Molecular modeling of dissociative and non-dissociative chemisorption of nitrosamine on close-ended and open-ended pristine and Stone-Wales defective (5,5) armchair single-walled carbon nanotubes

The nitrosamine adsorbed on close-ended and open-ended pristine and Stone-Wales defective (5,5) armchair single-walled carbon nanotubes (SWCNTs) was studied using the B3LYP/6-31G(d) method. Structure optimization of all possible adsorption configurations based on the combination of two nitrosamine (amino- and imino-) isomers and four types of nanotubes was carried out. The most stable configuration for the nitrosamine adsorbed on the (5,5) armchair SWCNTs was found to be dissociative chemisorption. The adsorption energies of the most stable structures of the adsorption complexes of close-ended and open-ended pristine SWCNTs with the imino isomer of nitrosamine were -127.15 and -137.14 kcal mol(-1), respectively.