Overview
Maharjan and Shakya bought 37 chocolate brands in Kathmandu grocery shops, grouped them as milk-based, cocoa-based or sugar-based from their labels, and measured cadmium, nickel and lead by flame atomic absorption spectrometry with three batches per brand. Cocoa-based chocolates had the highest levels of all three metals. The authors also estimated hazard indices and cancer risk for children and adults.
Key numbers
- Cocoa-based chocolate (n=10): cadmium “0.375 ± 0.098”, nickel “5.66 ± 1.09”, lead “3.09 ± 0.94” mg/kg (Table 2).
- Milk-based chocolate (n=15): cadmium “0.161 ± 0.047”, lead “1.51 ± 0.46” mg/kg; sugar-based (n=12): cadmium “0.060 ± 0.012”, lead “1.23 ± 0.53” mg/kg (Table 2).
- Overall means: cadmium 0.199, nickel 4.22, lead 1.94 mg/kg (Table 2).
Methods (brief)
Samples were dried at 70 °C, ground, digested with nitric acid and hydrogen peroxide in a block digester at 80 °C and read by flame AAS. Spike recoveries with NIST-traceable standards were 99.6 percent for cadmium, 97.8 for nickel and 98.2 for lead. Detection limits were 9.0, 3.0 and 9.0 µg/L in solution. Per-brand values are not printed.
Evidence Fitness
A reasonable brand count with batch replicates and spike recoveries, though no certified reference material. Lead near 2 to 4 mg/kg is high compared with most chocolate surveys analysed by more sensitive methods, so the values should be weighed with that in mind. The categories are label-based, and the basis (after drying at 70 °C) is not stated. The abstract’s lead maximum (4.29 mg/kg) differs from Table 2 (4.21 mg/kg). Plain chocolates are direct evidence for chocolate and only a proxy for chocolate-nut-candy, which is not linked.