Grochowska-Niedworok et al. 2020 — Cadmium and lead in Polish tomatoes and tomato products
This Polish study assessed cadmium and lead contamination across 25 samples of fresh tomatoes (multiple varieties and farming systems) and processed tomato products (concentrates, purees, juices, sauces, dried tomatoes), comparing measured concentrations against EU maximum levels set in Commission Regulation (EC) No 1881/2006. Nearly all samples fell within regulatory limits; the sole exceedance was a canned tomato concentrate with Cd at 0.064 mg/kg fresh weight, modestly above the 0.050 mg/kg EU limit. The study found generally low contamination levels consistent with tomatoes being among the least heavy-metal-laden vegetable groups, while flagging that frequent consumption and the bioaccumulative nature of both metals warrant ongoing monitoring.
Key numbers
All values are wet weight (fresh mass) unless specified as dry mass (mg/kg).
Table 2 — Raw tomatoes and processed products (fresh mass basis):
| Product | Cd (mg/kg fw) | Pb (mg/kg fw) |
|---|---|---|
| Tomato concentrate (glass jar) | 0.034 ± 0.004 | < LOQ |
| Tomato concentrate (can) | 0.064 ± 0.003 | 0.005 ± 0.001 |
| Cherry tomato | 0.028 ± 0.035 | 0.020 ± 0.002 |
| Small-fruited strawberry tomato | 0.006 ± 0.001 | 0.018 ± 0.002 |
| Cherry tomato on a twig | 0.007 ± 0.001 | 0.014 ± 0.004 |
| Mini plum tomato | < LOQ | 0.022 ± 0.003 |
| Oblong plum tomato | < LOQ | 0.007 ± 0.001 |
| ”Jawor” tomato (organic) | < LOQ | < LOQ |
| Canned tomatoes (whole) | 0.006 ± 0.001 | 0.006 ± 0.001 |
| Tomato purée | 0.024 ± 0.004 | < LOQ |
| Tomato juice | 0.018 ± 0.003 | < LOQ |
| Tomato sauce | 0.008 ± 0.001 | 0.006 ± 0.001 |
| Tomato sauce (ketchup) | 0.013 ± 0.002 | < LOQ |
LOQ for both Pb and Cd: 0.004 mg/kg (= 4 ppb fresh weight).
Table 3 — Dried and dry-mass samples (dry mass basis):
| Product | Cd (mg/kg dm) | Pb (mg/kg dm) |
|---|---|---|
| Cherry tomato | < LOQ | < LOQ |
| Small-fruited strawberry tomato | < LOQ | < LOQ |
| ”Koralik” cherry tomato (organic) | 0.071 ± 0.004 | 0.139 ± 0.004 |
| Cherry tomato on a twig | 0.012 ± 0.004 | < LOQ |
| ”Ożarowski” pink tomato | 0.015 ± 0.002 | < LOQ |
| ”Lima” tomato (organic) | 0.216 ± 0.004 | 0.026 ± 0.002 |
| Orange tomato (organic) | 0.206 ± 0.012 | 0.031 ± 0.040 |
| Mini plum tomato | < LOQ | < LOQ |
| Oblong plum tomato | < LOQ | < LOQ |
| ”Gargamel” large-fruited tomato | 0.076 ± 0.004 | 0.087 ± 0.002 |
| Dried tomatoes with spices (Turkey) | 0.055 ± 0.002 | < LOQ |
| Dried tomatoes organic (Turkey) | 0.107 ± 0.005 | < LOQ |
Average Cd across all samples: 0.017 mg/kg fresh weight. Average Pb across all samples: 0.021 mg/kg fresh weight.
EU regulatory limits referenced: Cd 0.050 mg/kg fw, Pb 0.100 mg/kg fw for tomatoes (EC No 1881/2006). The canned tomato concentrate exceeded Cd at 0.064 mg/kg fw. After moisture-adjusted conversion for dried samples, no dry-mass sample exceeded limits.
Note on organic vs. conventional: organic tomatoes showed notably higher Cd in dry-mass measurements (0.071 to 0.216 mg/kg dm vs. lower conventional values), consistent with literature suggesting organic soils may have different cadmium accumulation dynamics. No corresponding pattern was observed for lead.
Methods (brief)
Analytical method: flameless atomic absorption spectrometry (AAS), SavantAA Sigma spectrometer with GF 3000 graphite furnace (GBC, Poland). Wavelengths: 228.80 nm (Cd), 217.00 nm (Pb). Sample preparation: pressure mineralisation using microwave energy (Magnum II, ERTEC, Poland). Unprocessed tomatoes were dried at 60°C then 105°C and ground prior to mineralisation; processed tomato products were analysed directly. Three readings per sample; result is arithmetic mean. LOQ for both metals: 0.004 mg/kg. Only Cd and Pb measured; no speciation performed. All values reported as wet weight (fresh mass) for regulatory comparison or dry mass where stated; dry-mass values were converted to fresh-mass equivalents using mean water content for regulatory comparisons.
Limitation: small convenience sample (n = 25 products); Polish market sourcing limits generalisability across EU supply chains. Single-laboratory study with no interlaboratory validation reported.
Implications
Certification: Cd levels in Polish-market tomato products are generally well below the EU 50 ppb fresh-weight limit, but one canned concentrate exceeded it. The packaging-migration pathway (metal can) is flagged as a contributing factor to elevated Cd in the concentrate vs. glass jar. HMT&C tomato product standards should note that metal-can packaging may elevate Cd above glass-packaged equivalents from the same source material.
Courses: Illustrates that organic production does not reliably reduce heavy metal contamination; organic tomatoes in this dataset showed higher Cd on a dry-mass basis. Useful case study for supply-chain course modules on the limits of “organic” as a contamination proxy.
App: Fresh tomato Cd values cluster at 0.006–0.028 mg/kg fw (6–28 ppb); Pb values 0.006–0.022 mg/kg fw (6–22 ppb) for most varieties. Tomato concentrate in metal cans may run higher for Cd (64 ppb fw observed). These values can seed tomato and tomato-product contamination profiles.