Cantoral et al. 2024 — Dietary cadmium risk assessment across 143 Mexican foodstuffs
This 2024 cross-sectional monitoring study measured cadmium (Cd) concentrations in 143 foodstuffs commonly purchased in Mexico City, covering 14 food groups, using atomic absorption spectrophotometry. Of the 143 samples, 68.5% (n = 98) had detectable Cd concentrations (>LoQ), with the highest individual values found in oyster mushrooms (0.575 mg/kg), romaine lettuce (0.335 mg/kg), and cocoa powder (0.289 mg/kg), with ancho chili and romaine lettuce exceeding the FAO/WHO maximum level (ML). Theoretical Cd intake modeled against Mexican Dietary Guidelines yielded weekly estimates of 1.80, 2.06, and 3.83 µg/kg BW for adults, adolescents, and school-age children, respectively — a health risk only for school-age children, who exceed the EFSA TWI of 2.5 µg/kg BW by 53.2%.
Key numbers
- Total samples: n = 143 across 14 food groups, collected April 2022 to January 2023, Mexico City retail outlets
- Detection rate: 68.5% (n = 98) of foodstuffs had detectable Cd above LoQ
- Top Cd concentrations (wet weight): oyster mushrooms 0.575 mg/kg, romaine lettuce 0.335 mg/kg, cocoa powder 0.289 mg/kg, chocolate powder 0.117 mg/kg, saladette tomatoes 0.095 mg/kg, breadcrumbs 0.069 mg/kg, chocolate bars 0.060 mg/kg, ancho chili 0.059 mg/kg, chard 0.058 mg/kg, mushrooms (Agaricus bisporus) 0.055 mg/kg
- ML exceedances: ancho chili (0.059 mg/kg vs. ML 0.05 mg/kg) and romaine lettuce (0.335 mg/kg vs. ML 0.2 mg/kg)
- Food group means (detectable values): vegetables 0.084 mg/kg (range 0.006–0.575), snacks/sweets/desserts 0.049 mg/kg (range 0.004–0.289), cereals 0.026 mg/kg (range 0.005–0.069)
- Baby foods mean: 0.010 mg/kg (range 0.004–0.023); 9 of 12 baby foods had detectable Cd (75%)
- Rice samples (3 polished brands): 0.017–0.031 mg/kg
- Cocoa powder: 0.289 mg/kg (single sample)
- Chocolate bars: 0.060 mg/kg; dark chocolate bars: 0.029 mg/kg
- Theoretical Cd intake by age group: adults 1.80 µg/kg BW/week, adolescents 2.06 µg/kg BW/week, school children 3.83 µg/kg BW/week
- EFSA TWI for Cd: 2.5 µg/kg BW/week; exceeded by school children by 53.2%
- Vegetables contributed 63–68% of total theoretical weekly Cd intake across all age groups
Methods (brief)
Samples collected from retail outlets in Mexico City, April 2022–January 2023. Cd analyzed by graphite furnace atomic absorption spectrophotometry (AAS, Perkin Elmer AAnalyst-600 with AS800 autosampler). Standard addition technique for non-perishable foods; direct acid digestion for perishable foods. Calibration curve 0.5–2 µg/L; reference material NIST 1577c bovine liver (recovery 100.9 ± 13.6%). Concentrations expressed as wet weight. Statistical analysis in STATA 17.
Limitations
Cocoa powder Cd value (0.289 mg/kg) is a single sample; not representative of the full Mexican market distribution. Theoretical intake calculation relies on Mexican Dietary Guidelines portion recommendations, not actual measured consumption. No geographic breakdown within Mexico City. Extreme values identified by Chauvenet’s criterion and excluded from intake calculations (not from occurrence reporting). No speciation — total Cd only.
Implications
- Certification: Cocoa powder at 0.289 mg/kg wet weight is relevant to HMT&C cocoa limits context. This is a single Mexican market sample and substantially below EU ML (0.9 mg/kg for ≥70% cocoa solids products) but provides a Latin American market reference point distinct from EU occurrence surveys.
- Courses: Strong illustration of how vegetables — not seafood or chocolate — dominate cadmium exposure in a population following dietary guidelines. School children at greatest risk due to body-weight scaling.
- App: Vegetables category mean 0.084 mg/kg is a useful Mexican-market reference for leafy vegetable Cd where ingredient origin is unknown. Rice values (0.017–0.031 mg/kg) consistent with other polished-rice surveys globally.
- Microbiome: Not primary topic.