Clinical Pharmacist and Master’s student in Clinical Pharmacy with research interests in pharmacovigilance, behavioral interventions in mental health, and AI applications in clinical decision support. Experience includes digital health research with Bloomsbury Health (London) and pharmacovigilance practice in patient support programs. Published work covers drug awareness among healthcare providers, postpartum depression management, and patient safety reporting. 
Clinical Pharmacist and Master’s student in Clinical Pharmacy with research interests in pharmacovigilance, behavioral interventions in mental health, and AI applications in clinical decision support. Experience includes digital health research with Bloomsbury Health (London) and pharmacovigilance practice in patient support programs. Published work covers drug awareness among healthcare providers, postpartum depression management, and patient safety reporting. What was reviewed?
This review article comprehensively addresses the factors influencing cadmium (Cd) accumulation and mitigation in spinach and carrots, focusing on implications for food safety and the US FDA’s Closer to Zero initiative. The review synthesizes literature on cadmium sources, soil and crop interactions, phytoavailability, bioavailability, and various mitigation strategies relevant to heavy metal certification programs. Through analysis of soil chemistry, crop genetics, agricultural management, and regulatory frameworks, the review aims to inform producers and stakeholders about practical options for reducing Cd uptake by crops, with an emphasis on spinach and carrots due to their nutritional importance and frequent inclusion in infant and child diets.
Who was reviewed?
The review draws upon a wide array of primary research studies, global field trials, regulatory documents, and workshop proceedings. It covers evidence from laboratory and field experiments involving spinach, carrots, and other crops relevant to cadmium uptake or mitigation. Key populations considered include US agricultural regions with elevated soil Cd, producers, extension services, regulators, and researchers. The review also incorporates insights from collaborative workshops that included growers, academic experts, and government agencies, ensuring perspectives reflect both scientific findings and practical industry experience.
Most important findings
| Critical Points | Details |
|---|---|
| Sources and distribution of Cd in US soils are both geogenic and anthropogenic, with some regions ideal for produce having elevated Cd. No regulatory limits exist for Cd in US agricultural soils. | Both natural (e.g., weathering of phosphate rocks, shales) and human activities (fertilizer application, industrial emissions) contribute to soil Cd. Soil Cd can reach up to 9 mg/kg in some areas. Agricultural management decisions must consider these sources as spatial and depth variability influence phytoavailability. |
| Cd uptake (phytoavailability) in crops is affected by soil properties (pH, organic matter, Zn, Cl-, and other amendments). | Organic amendments like compost, manure, and biochar can reduce Cd uptake by increasing soil adsorption capacity, but biosolid use is limited by microbiological food safety regulations. |
| Zinc enrichment in soil is a particularly effective mitigation for reducing Cd uptake in spinach; less so for carrots, where pH and organic matter are more critical. | Field and pot studies show Zn fertilization (e.g., ZnSO4 at 25-100 kg/ha) can reduce spinach Cd by 53-81%. Combining Zn with lime and biosolids compost achieves the greatest reductions. For carrots, raising pH to 7.0 and increasing organic matter reduce Cd accumulation; evidence for Zn impact is weaker. |
| Up to 30-fold variation in carrot and 3.3-fold in spinach Cd accumulation was observed among genotypes. Breeding and molecular approaches (e.g., targeting HMA3 gene) offer long-term solutions but are not yet widely available. Regulatory and market adoption will be needed. | Compost and biosolids (with low Cd content) decrease Cd phytoavailability, but their use must comply with FDA and EPA standards to manage pathogen risks. Biochar is promising but needs more field validation in US vegetable systems. |
| Crop breeding for low-Cd cultivars is ongoing, with significant genotypic variation identified in both spinach and carrot germplasms. | Up to 30-fold variation in carrot and 3.3-fold in spinach Cd accumulation was observed among genotypes. Breeding and molecular approaches (e.g., targeting the HMA3 gene) offer long-term solutions but are not yet widely available. Regulatory and market adoption will be needed. |
| Mitigation strategies must balance Cd risk reduction with food safety (e.g., avoiding increased pathogen risk from amendments or antimicrobials) and consider economic feasibility for growers. | For example, reducing Cl- in irrigation may lower Cd but could compromise microbial safety if chlorine-based antimicrobials are reduced. Zn and lime applications have cost and operational implications. Industry-researcher collaboration is critical for pragmatic solutions aligned with regulatory standards. |
| Bioavailability of Cd in crops is influenced by the presence of Fe, Zn, and Ca in the crop; higher levels of these nutrients can reduce intestinal Cd absorption. | Spinach and carrots, rich in Fe and Zn, may confer some protection against Cd absorption in humans, but this effect varies with crop composition and consumer nutrition status. Mitigation measures that increase Zn in crops may further reduce Cd bioavailability. More research is needed to quantify these effects for risk assessments. |
Key implications
This review demonstrates that effective cadmium mitigation for heavy metal certification in spinach and carrots requires a holistic approach considering soil chemistry, crop genetics, and management practices. Industry stakeholders should prioritize soil testing for Cd and Zn, judicious amendment use, and cultivar selection. Regulatory guidance must balance heavy metal risks with food safety and economic sustainability. Continued research and collaboration among growers, scientists, and agencies are essential for developing and implementing region-specific, cost-effective Cd mitigation strategies, ensuring both consumer safety and produce marketability.
Citation
Chaney RL, Forte D, Seyfferth AL, Smith RF, Abt E, McEntire JC, Griep-Moyer ER, Sanyal D, Davis DAP. Factors Affecting Cadmium Accumulation and Mitigation: A Literature Review to Inform Spinach and Carrot Producers. HortScience. 2025;60(11):1908–1917. https://doi.org/10.21273/HORTSCI18707-25
Cadmium is a persistent heavy metal that accumulates in kidneys and bones. Dietary sources include cereals, cocoa, shellfish and vegetables, while smokers and industrial workers receive higher exposures. Studies link cadmium to kidney dysfunction, bone fractures and cancer.
