*3.2. Concentration of Metals*

Honey is a plant and animal product that contains macro- and microelements as well as heavy metals (Pb, Cd, Hg, Cu, and Zn). Their concentrations vary depending on regional and environmental conditions, seasonal differences, and beekeeping and agricultural techniques [36].

Mercury is considered to be the most toxic heavy metal in the environment [37]. In the present study, the LOQ for Hg (5.0 μg/kg) was not exceeded in the honey. Brodziak-Dopierała et al. [38] detected the presence of Hg in 32 honeys from different parts of Poland (on average 0.37 μg/kg). The highest Hg content was noted in honeydew honey (1.55 μg/kg) and the lowest in goldenrod honey (0.02 μg/kg). In honey from Romania, the average Hg level was 0.908 μg/kg, ranging from 0.369 μg/kg to 2.154 μg/kg [14].

The level of elements in honey is associated with pollution in the area in which bees fly around honey plants. According to EC Regulation 1881/2006 [39], honey (as a food product) must meet the requirements for the maximum level of Pb (0.10 mg/kg). However, no limit has been established for Cd [36]. Tomczyk et al. [40] tested levels of Cd and Pb in successive links of the food chain (soil-plant-bee-honey) and showed that bees are susceptible to their bioaccumulation but at the same time are a biological barrier preventing the transfer of these elements to honey.

In the present study, the lowest Pb content was noted in honeydew honey (0.044 mg/kg) and the highest in linden (0.080 mg/kg) and rapeseed (0.081 mg/kg) honey (Figure 1). Due to the considerable variation in the Pb concentration in the honey samples, the differences were not confirmed statistically. The acceptable Pb concentration was exceeded in four honey samples, including one sample of rapeseed honey (0.107 mg/kg), two samples of linden honey (0.158 and 0.114 mg/kg), and one sample of multifloral honey (0.191 mg/kg). Piven et al. [2] reported a higher Pb content in Ukrainian honey (from the Odessa region), with the highest concentration noted in sunflower honey (0.24 mg/kg) and the lowest in multifloral honey (0.13 mg/kg). According to the authors, the high Pb level in honey was caused by the proximity of the apiaries to traffic routes. Aghamirlou et al. [41] reported a Pb content of 0.45 mg/kg in multifloral honey from Iran. An excessive

Pb content in honey poses a threat to people mainly due to its neurotoxic and nephrotoxic effects [42].

**Figure 1.** Content of Pb (mg/kg) in varietal honeys (BW—buckwheat; LI—linden; RS—rapeseed; HD—honeydew; MF—multifloral).

The Cd content in the present study did not exceed the LOQ of 0.02 mg per kg of honey, except for one sample of linden honey (0.0215 mg/kg). Piven et al. [2] reported Cd at a level of 0.03 mg/kg in sunflower honey from the Odessa region (Ukraine). Aghamirlou et al. [41] detected Cd at a level of 0.013 mg/kg in multifloral honey from Iran.

The Cu content in the honey was significantly influenced by the variety (*p* = 0.0013) (Figure 2). The Cu content was significantly the highest in buckwheat honey (1.201 mg/kg) and the lowest in rapeseed, linden, and multifloral honey (0.504–0.579 mg/kg). Dzugan et al. ˙ [43], in an analysis of Polish varietal honeys from the Podkarpacie region (southeastern Poland), showed a lower average Cu content in multifloral (0.21 mg/kg), rapeseed (0.05 mg/kg), linden (0.20 mg/kg), and honeydew (0.03 mg/kg) honey, and the highest Cu content in buckwheat honey (0.86 mg/kg), as in the present study. Tarapatskyy et al. [44], in honey obtained in Pogórze Karpackie (southern Poland), reported a Cu content similar to the levels found in the present study in multifloral (0.410 mg/kg), linden (0.460 mg/kg), and honeydew (0.960 mg/kg) honey.

The honey variety did not affect the Zn level, although it was highest in buckwheat honey (2.694 mg/kg) compared with the other varieties (0.657–1.500 mg/kg) (Figure 3). Dzugan et al. [ ˙ 43] reported similar results for Zn in honey varieties, with the exception of honeydew honey, in which the level was twice as high as in our study (2.33 mg/kg). Similarly, in the study by Tarapatskyy et al. [44], the Zn level in honeydew honey from Pogórze Karpackie (Poland) was twice as high as in the present study, while its content in buckwheat honey was only a third as high. In general, the literature reports indicate a considerable variation in the content of the elements analysed (macro- and microelements and toxic metals) in European varietal honeys from Poland [21,45,46], Slovakia [44,47], Romania [14], and Turkey [36,48]. The contamination of honey with toxic metals is mainly associated with industry and agriculture [45]. Numerous studies supply valuable information on the effect of the environment on the quality of honey produced in industrial areas. Honey obtained from industrialized areas or near major roads has been shown to have higher concentrations of heavy metals.

**Figure 2.** Content of Cu (mg/kg) in varietal honeys (RS–rapeseed; MF–multifloral; HD—honeydew; BW—buckwheat; LI—linden). Means with different letters (A, B) differ significantly (*p* < 0.01).

**Figure 3.** Content of Zn (mg/kg) in varietal honeys (RS—rapeseed; MF—multifloral; HD—honeydew; BW—buckwheat; LI—linden).

Bartha et al. [49] analysed the content of heavy metals (Pb, Cd, Zn, and Cu) in multifloral honey produced in an industrial area of Romania, considered to be one of the most polluted regions of Eastern Europe (the town of Cops, a Mică and its vicinity). The spread of pollutants emitted by the local industrial platform resulted from the topography of the area, where the main air masses are directed towards the corridors of the rivers Târnava Mare and Visa. Apiaries situated in the valley channeling pollutants from the industrial platform were shown to be more susceptible to the bioaccumulation of Pb than those situated in side valleys further from the source of pollution. The Cd concentration in the honey decreased exponentially with an increasing distance between the apiary and the pollution source, while the Cu concentrations increased linearly. The median for the elements was high: Pb—1.49 mg/kg, Cd—2.20 mg/kg, Zn—20.40 mg/kg, and Cu—3.70 mg/kg. According to Klym and Stadnytska [50], the content of heavy metals increased with the degree of the impact of industry on the environment. The levels of Zn, Cu, Pb, and Cd were the highest in honey from forested and steppe areas, lower in honey from foothills, and the lowest in mountainous areas of the Carpathian region. Dobrza ´nski et al. [51] found that the Pb limit was exceeded in 75% of the samples of honey from apiaries located in a copper-producing region but did not observe elevated levels of Cd. The honey in the present study contained much lower levels of residues of these elements.
