RISK ASSESEMENT OF THE LEVELS OF SELECTED HEAVY METALS (Pb, Cr, Fe, Ni, Mn, Zn) IN IMPORTED CHILDREN TOYS

Abstract

Toys are integral part of children’s developmental processes and apart from entertainment, it also serves as educational tools for them. Chemical exposure from metals picked up from toys, is an emerging concern because of the chewing, licking and swallowing behavior of children. The concentration and the availability of some heavy metals (Pb, Mn, Zn, Ni, Cr and Fe) were determined in some selected eighty (80) toy samples imported to Nigeria, in order to assess the risk posed by these metals to children. Ternary acid (HNO3 H2SO4 HCLO4 in the ratio 1:1:3) digestion was used to bring the metals into solution, followed by quantitative determination of the levels of the heavy metals in the toy samples by Atomic Absorption Spectrophotometer (AAS). The frequency distribution showed that 81% of the samples (65) were from China, while Japan (5), Hungary (2) and others (8) representing 6.5%, 2.5% and 10% of the total samples respectively. Pb, Cr and Ni were found in various levels of concentration in all of the samples (100%) while Mn, Fe and Zn had concentration ranges of between 23-56%. The concentration of the metals from the toys showed that Ni had the highest concentration of 20.497 mg/kg while Pb had the least concentration with 0.017 mg/kg. In general the metal concentration ranges as follows: Ni (0.245-20.497 mg/kg), Pb (0.017-11.3 mg/kg), Cr (0.068-11.324 mg/kg), Zn (0.03-1.591 mg/kg), Fe (0.025-1.373 mg/kg) and Mn (0.021-1.772 mg/kg). When compared to the European toy safety standards twenty two (22) of the total samples had concentration of Pb above the European toy safety standards, three (3) of the samples had concentration of Ni above the standard for nickel, 4 of the samples had concentration of Cr above the standards for chromium, the other metals all have their concentration below the toy safety standards for Mn, Zn, and Fe. Correlation analysis showed that each metal can be used interchangeably, so that less toxic metals can be used more in manufacturing of children toys. Correlation of the heavy metal concentrations with sample weight showed that weight of the samples does not determine the level of concentration of the heavy metal in the sample. Characterization of the risk assessment which was carried out by calculating the hazard quotient (HQ) for each of the metal, using two different age group (6-12 months and 1-2 years) showed that Pb presented a greater risk potential to children with HQ values as high as 322. This study shows that heavy metals are present in children toys imported to Nigeria. The concentration of these metals should be monitored in paints and pigments used in manufacturing children toys and more precautions need to be taken in production of children’s toy.