Heavy metals and natural radioactive isotopes in phosphate and compound fertilisers and their impact on human health

The paper presents the results of heavy metals (Ni, Cr, Pb, Cd, Zn and Cu) and natural radioactive isotopes (²³⁸U, ²²⁶Ra, ²³²Th and ⁴⁰K) in phosphate and compound fertilisers produced in Poland. Heavy metals in the mineral fertilisers were determined by atomic absorption spectrophotometry in the acetylene-air flame. The content of natural radioactive isotopes was determined using gamma-ray and alpha spectrometry techniques. The average heavy metal content of the tested fertilisers was 154 ± 17, 154 ± 30, 5.43 ± 0.43, 7.87 ± 1.95, 197 ± 19 and 26 ± 7 mg·kg^{- 1} for Ni, Cr, Pb, Cd, Zn and Cu, respectively. Whereas, the average concentrations of natural radioactive isotopes in the studied samples for ²³⁸U, ²²⁶Ra and ⁴⁰K were respectively in the range of 715 ± 259, 549 ± 170 and 2472 ± 759 Bq·kg^{- 1}, and were higher than their average content in the Earth's crust, in contrast to the average concentration of the 232Th isotope (12 ± 2 Bq·kg^{- 1}) in the tested samples compared to the average concentration in the Earth's crust. To assess the health exposure of people in direct contact with fertilisers (factory workers, people working in fertiliser loading and unloading, transporters, storekeepers or farmers), basic radiological protection parameters such as radium equivalent activity (Ra_eq), outdoor dose rate (D_out), indoor dose rate (D_in), annual outdoor effective dose and annual indoors effective dose (E_out and E_in) and total annual effective dose (E_tot) were determined. It was observed that the calculated radiological hazard parameters for all samples exceeded the worldwide average values.