Overview
Ghosh and Patel measured lead and cadmium in 10 commonly consumed spices from Patna retail markets, Bihar, India, using ICP-MS (Thermo Scientific iCAP TQe) with microwave acid digestion. A key methodological feature is the in-vitro bioaccessibility assessment using the INFOGEST 2.0 harmonised protocol (oral, gastric, small intestinal phases), providing the fraction of lead (Pb) and cadmium (Cd) that is physiologically absorbed after ingestion. All samples were below the EU MRL of 2.0 mg/kg for Pb. Cumin was among the lower-contamination spices for both metals; turmeric had the highest Pb (1.34 mg/kg, range 0.39-1.34 across rounds) and the highest Cd (0.23 mg/kg, approaching but not exceeding the EU Cd MRL for some product categories). THQ and HI values for all spices at NNMB-reported consumption rates were below 1 for both Pb and Cd individually and cumulatively.
Key numbers
Heavy metal concentrations (Table 1, mg/kg dry weight, ICP-MS, mean of 3 procurement rounds x 3 replicates):
| Spice | Pb (mg/kg) | Cd (mg/kg) | As (mg/kg, iAs) | Hg (mg/kg) | Ca (x10^3 mg/kg) | Mg (x10^2 mg/kg) |
|---|---|---|---|---|---|---|
| Black pepper | 0.87 | 0.12 | 0.09 | 0.10 | 4.37 | 12.1 |
| Turmeric | 1.34 | 0.23 | 2.4 | 1.83 | 1.94 | 41.2 |
| Red chili | 1.12 | 0.22 | 1.1 | 1.14 | 2.1 | 23.6 |
| Cumin | 0.739 | 0.009 | 1.4 | 12.43 | 9.31 | 66.3 |
| Coriander | 0.410 | 0.027 | 6.9 | 0.64 | 1.43 | 19.8 |
| Ginger | 0.489 | 0.027 | 0.9 | 0.64 | 1.43 | 10.8 |
| Cloves | 0.359 | 0.019 | 1.7 | 1.76 | 1.91 | 11.8 |
| Cardamom | 0.398 | 0.019 | 0.7 | 0.63 | 0.87 | 11.8 |
arsenic (As) values are reported as inorganic arsenic (iAs) in the paper’s table header. mercury (Hg) values for cumin (12.43 mg/kg) appear anomalously high relative to other spices and other published studies; this value should be verified against the original paper before use.
Cumin-specific values:
- Pb 0.739 mg/kg (below EU MRL of 2.0 mg/kg)
- Cd 0.009 mg/kg (well below EU MRL of 0.20 mg/kg for a subset)
- Pb range across three procurement rounds: 0.39-1.34 mg/kg not stated for cumin specifically; turmeric showed 0.39-1.34 range
Bioaccessibility (Table 2, % and EDI, Pb and Cd for selected spices):
| Spice | Pb bioacc (%) | Cd bioacc (%) | Pb EDI (ug/person/day) | Cd EDI (ug/person/day) | THQ(Pb) | THQ(Cd) | HI(Pb+Cd) |
|---|---|---|---|---|---|---|---|
| Turmeric | 31.4 | 27.8 | 0.103 | 0.018 | 0.021 | 0.007 | 0.028 |
| Black pepper | 24.8 | 24.1 | 0.034 | 0.005 | 0.007 | 0.002 | 0.009 |
| Red chili | 33.2 | 29.4 | 0.096 | 0.015 | 0.019 | 0.006 | 0.025 |
| Cumin | 26.1 | 21.7 | 0.032 | 0.004 | 0.006 | 0.001 | 0.007 |
| Coriander | 24.8 | 19.3 | 0.032 | 0.004 | 0.006 | 0.002 | 0.008 |
| Fenugreek | 29.6 | 25.2 | 0.027 | 0.004 | 0.005 | 0.002 | 0.007 |
All THQ <1 and HI <1 at NNMB spice consumption rates. Cumin bioaccessibility for Pb (26.1%) is in the mid-range across spices; for Cd (21.7%) it is the lowest reported.
EU MRLs referenced: Pb 2.0 mg/kg for spices; Cd 0.20 mg/kg for a subset of spices. All samples below Pb MRL; turmeric Cd (0.23 mg/kg) approached but did not exceed Cd MRL in one procurement round.
Methods (brief)
ICP-MS: Thermo Scientific iCAP TQe. Microwave-assisted acid digestion: 0.5 g ground spice + 8 mL HNO3 + 2 mL H2O2 in PTFE vessels (Milestone ETHOS One; 180 degrees C, 20 min, 800 W). Diluted to 50 mL with Milli-Q. Internal standards: In (187). Moisture gravimetrically determined (105 degrees C, 4 h). Three analytical replicates per sample. INFOGEST 2.0 bioaccessibility protocol: 0.5 g ground spice + simulated salivary fluid (pH 6.8, amylase 75 uranium (U)/mL, 2 min), gastric phase (pH 2.0, pepsin 2000 U/mL, 2 h), intestinal phase (pH 7.0, pancreatin 200 U/mL, bile extract 6 mM, 2 h). Centrifuged 3000 rpm, 10 min; supernatant analysed by ICP-MS.
Implications
Bioaccessibility data: This paper is one of few studies providing cumin-specific bioaccessible fractions for Pb and Cd. The Pb bioaccessibility of 26.1% for cumin means that of the 0.739 mg/kg total Pb, only approximately 0.19 mg/kg is estimated to be physiologically available. This is relevant context for interpreting total-Pb concentration data in cumin exposure assessments, which typically use total concentration as a conservative upper bound.
Cumin as a lower-risk spice within the Patna market sample: Cumin had the lowest Cd (0.009 mg/kg) and second-lowest HI of the six spices reported. This is consistent with the broader literature showing cumin generally below turmeric and chili for Pb and Cd in South Asian markets.
Procurement variability note: The study purchased from the same market across three rounds spanning mid-2022 to early 2024. The batch-to-batch variability seen in turmeric (highest Cd in January 2023 round exceeding EU benchmark) underscores that point-in-time results may not capture lot-to-lot variance.
Related evidence
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