Overview
This nationwide Bangladesh dairy survey reports concentrations of eight metals (Fe, Cu, Mn, Zn, Pb, Cd, Cr, total As) in cheese, ghee, and locally processed butter purchased from local shops across 64 administrative districts. Analysis is by flame atomic absorption spectrophotometry (AAS) on a Thermo Scientific iCE-3000, with microwave digestion in HNO₃/H₂O₂. The paper applies the standard EPA-based EDI / THQ / TTHQ / TCR risk framework for the adult population (60 kg BW), using the BBS 2011 Household Income and Expenditure Survey to set daily intake rates (cheese 14.053 mg/day, ghee 786.965 mg/day, butter 14.053 mg/day as stated by the authors).
The headline finding is that for cheese and butter all THQ and TTHQ values fall below 1 and TCR values for As, Pb, and Cd fall below 10⁻⁶, indicating negligible non-carcinogenic and carcinogenic risk at typical Bangladeshi adult consumption. For ghee, however, the TTHQ reaches 1.247 — above the threshold of concern — driven primarily by Cu, tAs, and Cd contributions in the much higher daily-intake matrix; the authors note this implies a potential adverse-health-effect signal for ghee specifically. Carcinogenic risk (TCR) for ghee remains within the conventionally acceptable 10⁻⁶ to 10⁻⁴ range for As and below 10⁻⁶ for Pb.
All concentrations are reported in ppm (mg/kg) on a fresh-weight basis as published; no wet/dry distinction is stated by the authors.
Key numbers
Mean heavy-metal concentrations (mg/kg fresh weight), back-calculated from the published EDIs (Table 2) using the stated intake rates and 60 kg BW:
| Metal | Cheese mean | Ghee mean | Butter mean |
|---|---|---|---|
| Fe | 0.561 | 0.526 | 0.477 |
| Cu | 0.733 | 1.091 | 1.524 |
| Mn | 0.071 | 0.097 | 0.124 |
| Zn | 0.141 | 0.451 | 0.450 |
| Pb | 0.0109 | 0.0138 | 0.0099 |
| Cd | 0.0306 | 0.0237 | 0.0316 |
| Cr | 0.474 | 0.343 | 0.510 |
| tAs | 0.0306 | 0.0109 | 0.0316 |
Reported ranges (Table 1, mg/kg, min – max as published):
| Metal | Cheese | Ghee | Butter |
|---|---|---|---|
| Fe | 0.168 – 0.586 | 0.251 – 0.541 | 0.358 – 0.656 |
| Cu | 0.118 – 2.300 | 0.212 – 12.000 | 0.228 – 3.394 |
| Mn | 0.041 – 4.314 | 0.025 – 0.256 | 0.041 – 0.247 |
| Zn | 0.091 – (see notes) | 0.162 – (see notes) | 0.136 – (see notes) |
| Pb | 0.005 – 0.025 | 0.006 – 0.018 | 0.005 – 0.016 |
| Cd | 0.016 – 0.042 | 0.012 – 0.036 | 0.014 – 0.041 |
| Cr | 0.076 – 0.886 | 0.018 – 0.542 | 0.071 – 0.841 |
| tAs | 0.005 – 0.088 | 0.005 – 0.018 | 0.005 – 0.082 |
The published Table 1 row for Zn maxima is internally inconsistent with the EDI-derived means; the Zn max columns are flagged in the source’s own table layout and could not be cleanly aligned to specific products without risk of misattribution. The mins above are clean; the means above are back-calculated from Table 2 EDIs and are the most defensible single-number representations.
Speciation notes: As is reported as total arsenic (tAs); no iAs speciation. Cr is total chromium (no Cr-VI speciation). The paper does not report Hg or Ni measurements (Ni is discussed only in the introductory toxicology background).
Estimated daily intake — adults, Table 2 (mg/day as published; units reflect Di × Mc / BW with Di in mg/day, Mc in mg/kg, BW in kg):
| Metal | Cheese EDI | Ghee EDI | Butter EDI |
|---|---|---|---|
| Fe | 0.13145 | 6.8942 | 0.11178 |
| Cu | 0.17171 | 14.3068 | 0.35708 |
| Mn | 0.01666 | 1.2699 | 0.02893 |
| Zn | 0.03309 | 5.9223 | 0.10553 |
| Pb | 0.00255 | 0.18143 | 0.00232 |
| Cd | 0.00717 | 0.31102 | 0.00741 |
| Cr | 0.11108 | 4.4968 | 0.11941 |
| tAs | 0.00717 | 0.14255 | 0.00741 |
Target Hazard Quotient (THQ, Table 3, adults): all individual THQs <1 across all three matrices and all eight metals. The highest single-metal THQ is tAs in ghee at 0.475, followed by Cu in ghee 0.358 and Cd in ghee 0.311.
Total Target Hazard Quotient (TTHQ, Table 4, adults):
| Matrix | TTHQ |
|---|---|
| Cheese | 0.03672 |
| Ghee | 1.24719 |
| Butter | 0.04279 |
Ghee TTHQ exceeds 1, indicating potential cumulative non-carcinogenic adverse-health-effect signal; cheese and butter are well below.
Target Carcinogenic Risk (TCR, Table 5 + body text):
| Metal | Cheese TCR | Ghee TCR | Butter TCR |
|---|---|---|---|
| tAs | 1.793 × 10⁻⁷ | 3.564 × 10⁻⁶ | 1.85 × 10⁻⁷ |
| Pb | 3.613 × 10⁻¹⁰ | 2.57 × 10⁻⁸ | 3.29 × 10⁻¹⁰ |
| Cd | 1.793 × 10⁻⁶ | 7.776 × 10⁻⁵ | 1.853 × 10⁻⁶ |
(The Cd row appears in the body text rather than in Table 5 as printed.) Ghee Cd TCR (7.78 × 10⁻⁵) sits in the conventionally acceptable 10⁻⁶ to 10⁻⁴ range; ghee tAs TCR (3.56 × 10⁻⁶) is just above the 10⁻⁶ minimal-risk threshold. All cheese and butter TCR values are below 10⁻⁶.
Methods (brief)
Sampling: 128 each of cheese, ghee, and butter (n=384 total) purchased from local shops across 64 administrative districts of Bangladesh, sterile-glass-bottle collection, 4 °C transport, analysis within 24 h of receipt. Sampling and analysis at BCSIR Institute of Food Science and Technology, October 2018 – July 2019.
Digestion: 0.3 g sample + 5 mL 65 % HNO₃ (Merck) + 2 mL 30 % H₂O₂ (Merck); microwave (Berghof Speedwave, Germany), 3-step program, max 200 °C, 35 bar, 90 % power; diluted to 25 mL with Milli-Q water; 0.45 µm PTFE syringe filtration.
Quantification: AAS (Thermo Scientific iCE-3000) with element-specific spectral lines (Cd 228.67; Cr 357.65; Cu 324.57; Mn 279.43; Pb 217.35; Fe 213.9; Zn 248.30; As 193.7 nm). Four-point calibration at 0.01, 0.1, 1.0, 5.0 ppm using Sigma-Aldrich standards. Stated detection limits (mg/kg): 0.005 for Cr and Zn; 0.002 for Mn and Pb; 0.001 for Cd, Fe, Cu (As LOD not explicitly stated). Sigma-Aldrich certified reference materials used for accuracy verification (material identity not specified).
Risk assessment: EDI computed as Di × Mc / BW with Di from BBS 2011 HIES values (cheese 14.053 mg/day; ghee 786.965 mg/day; butter 14.053 mg/day) and BW = 60 kg (Bangladeshi adult average per Shaheen et al. 2016). THQ uses RfDs from US EPA IRIS (Fe 0.7; Cu 0.04; Mn 0.05; Zn 0.3; Pb 0.004; Cd 0.001; Cr 1.5; As 0.0003 mg/kg-BW/day). TCR uses oral CSFs of 1.5 (As), 0.0085 (Pb), 15 (Cd) mg kg⁻¹ day⁻¹, with EFr 365 days/year and ED 70 years for lifetime adult exposure.
Statistics: one-way ANOVA, Pearson correlation; Microsoft Excel 2016 and XL-stat v17.
Key limitations: Table 1 publishes only min/max ranges (no SD or n-per-cell), and the Zn max column is internally inconsistent with the back-calculated means, indicating likely table-layout or typesetting errors in the published article. The intake-rate units in Table 2 are reported as “mg/day” but the magnitudes (especially ghee at 786.965) are more consistent with values originally expressed in g/day or another unit before transposition into the EDI formula; the absolute EDI/THQ/TCR numbers should therefore be treated as illustrative of the relative cross-matrix gradient rather than directly portable to other populations. No As LOD is given. Reference-material identity not specified. Wet/dry basis not stated explicitly (conventional interpretation: as-sold/wet for cheese and butter; ghee is intrinsically anhydrous). Brand/source identity is not reported at the sample level, so contamination-source attribution (feed, environment, processing equipment, packaging) cannot be untangled. No speciation for As or Cr.
Implications
Certification: For butter and ghee within the HMI scope, this study contributes mean and range data on Pb, Cd, tAs, and Cr (and supporting Fe/Cu/Mn/Zn nutritional metals) from a 384-sample nationwide Bangladeshi survey. The ghee subset is the most policy-relevant finding: very high reported daily intake combined with detectable Cu, Cd, and tAs produces a TTHQ above 1 and a Cd-driven TCR in the acceptable-but-non-trivial range for adults. For cheese, the authors state that all per-metal EDIs fall below the “permissible value” they reference (Table 7 of the paper); they do not cite a specific named regulation.
Courses: Useful as a worked example of the EDI/THQ/TTHQ/TCR framework applied to a fat-rich anhydrous matrix (ghee), where high reported per-capita intake produces a cumulative hazard signal even from individually-low per-metal concentrations. Also a teaching example of the importance of basis (anhydrous ghee vs hydrated cheese/butter) when comparing across dairy matrices.
App: Supports flagging ghee as a higher-cumulative-exposure dairy matrix for Pb, Cd, and tAs in South-Asian dietary patterns, while cheese and butter contribute negligibly to lifetime risk in this population.
Related evidence
Update history
No substantive edit history is available in this build. The full commit record is available in git.