The level of wheat grain contamination with lead and cadmium was determined using electrothermal atomic absorption spectrometry with Zeeman background correction (ETAAS) after microwave digestion. The obtained limits of quantification were 0.001 mg∙kg–1, for both metals. A total of 300 samples of wheat grain from agricultural regions of Poland were examined, 150 each from the two consecutive harvest years 2017 and 2018.
None of the tested samples exceeded the maximum level of these metals, as specified in the European regulations. The contents of lead and cadmium in wheat grain from both years of harvest ranged from <0.001 to 0.098 mg∙kg ^–1 and from 0.006 to 0.098 mg∙kg ^–1, respectively. Despite similar ranges of these metals, the highest lead contents were two times lower than the maximum limit value, while the highest cadmium contents were close to it.
As for lead, a significantly higher (p < 0.05) mean content of this metal was found in wheat grain from the 2018 harvest compared to 2017 and in the western compared to eastern regions of the country. However, the cadmium contents did not differ significantly between the two harvest years, but were significantly higher (p < 0.05) in wheat grain from the southern regions compared to northern regions of Poland. Additionally, the highest contents of cadmium, close to the maximum limit, were found in the South-West region and in the both years of harvest.
The risk analysis of the occurrence of the excessive contents of toxic metals in wheat grain showed a low risk level for lead in all investigated regions, and a medium level for cadmium, in general.