According to the literature, maternal diet and living environment can affect levels of elements and fatty acid (FA) composition and their stable isotopes in human milk. The content of ω-6 and ω-3 polyunsaturated fatty acids (PUFAs), could be related to the optimal growth and development of the baby. Higher intake of seafood could increase the content of ω-3 PUFAs, but it should be taken into account, that fish also contain Hg compounds acting as neurotoxicants. Therefore, the evaluation of fish intake in context of potential risks and potential benefits should be done.

Since the FA composition is correlated with the diet, the analysis of stable isotope ratio (13C/12C, expresses as δ13C) could be used for tracking dietary habits. Variation in isotopic composition of carbon (13C/12C) occurs due to differences in fixation pathways which are correlated with environmental and physiological conditions.

To investigate the relationship, information obtained from questionaries’ and analytical data on milk samples (4-6 weeks after delivery) of 74 delivering women (20-38 years) and their newborns from area of Koper and area of Murska Sobota from HBM in Slovenia (2007-2014) were used.

Levels of selected toxic and potentially toxic elements were analysed using an Inductively-coupled plasma mass spectrometry (ICP-MS) for As, Cd, Cu, Mn, Pb, Se and Zn for milk samples and cold vapour atomicabsorption spectrometry (CVAAS) for Hg in milk. Identification and quantification of FAs in maternal milk were performed by in-situ trans-esterification method (FAMEs). The characterization of FAMEs were performed by gas chromatography with FID detector (GC-FID), equipped with a capillary column (Omegawax 320), while δ13CFA were determined using Isoprime GV GC-C-IRMS system, using a capillary column DB-1MS.

Associations between those areas and a) predictors obtained through questionnaires and b) levels of selected elements, FA composition and stable isotopes of individual FA in maternal milk samples were tested using univariate and multiple linear regression.

Levels of selected elements did not represent any health risk for the mother-child pairs. Levels of As and Hg in milk were statistically higher in the coastal than in the inland area, so were the levels of saturated and monounsaturated FA. Whereas PUFAs, ω-3, ω-6 levels were lower in the costal than in the inland area, despite higher intake of fresh sea food observed in the coast. The ratio ω-6/ω-3 levels did not differ significantly among the studied areas.