The Safety Assessment of Toxic Metals in Commonly Used Herbs, Spices, Tea, and Coffee in Poland

Abstract

The presented study was aimed at the determination of the level of contamination with heavy metals (Cd, Pb, As, and Hg) in 240 samples of plant materials, i.e., herbal raw materials, spices, tea, and coffee. Moreover, a probabilistic risk assessment (noncarcinogenic and carcinogenic risks) was estimated by models including target hazard quotient (THQ) and cancer risk (CR). The samples were subjected to microwave mineralisation with the use of HNO3 (65%), while the determination of the content of the elements was performed with the use of inductively coupled plasma mass spectrometer (ICP–MS) and a mercury analyser. The element which was characterised by the highest level of accumulation in the analysed samples was lead (from 0.010 to 5.680 mg/kg). Among the heavy metals under analysis, the lowest concentration was noted in the case of mercury (from 0.005 to 0.030 mg/kg). A notably higher level of contamination with heavy metals was noted in the analysed samples of herbs and spices (0.005–5.680 mg/kg), compared to samples of tea and coffee (0.005–0.791 mg/kg). According to the guidelines of the World Health Organisation (WHO) concerning the limits of contamination of samples of herbal raw materials with heavy metals, lead levels exceeding the limits were only noted in 24 samples of herbs (18%). In all of the analysed samples of spices, tea, and coffee, no instances of exceeded limits were noted for any of the analysed heavy metals. The values of TTHQmax (in relation to the consumption of the analysed products) were as follows: up to 4.23 × 10−2 for spices, up to 2.51 × 10−1 for herbs, up to 4.03 × 10−2 for China tea, and up to 1.25 × 10−1 for roasted coffee beans. As the value of THQ ≤1, there is no probability of the appearance of undesirable effects related to the consumption of the analysed group of raw materials and products of plant origin. The CR value for As (max. value) was 1.29 × 10−5, which is lower than the maximum acceptable level of 1 × 10−4 suggested by United States Environmental Protection Agency (USEPA).