Phosphate fertilizers and cadmium exposure risks

By
Dario Dongo
-
0
1985
Food Times_phosphate fertilizers_cadmium_public health risks

Phosphate fertilizers and cadmium exposure risks present serious public health threats, including increased risks of tumors, DNA damage, and cardiovascular diseases (CVDs), in France and beyond. On June 5, 2025, World Environment Day, the French Regional Unions of Liberal Physicians (Unions Régionales des Médecins Libéraux, URML) issued a critical warning that ‘cadmium, a confirmed carcinogenic heavy metal (Group 1, IARC), is ubiquitous in our environment and accumulates in the human body for 10 to 20 years’ (URML, 2025).

Chronic cadmium exposure, largely linked to phosphate fertilizer use in conventional agriculture, elevates the risks of cancers (lung, prostate, pancreas, liver, kidney), DNA damage, renal insufficiency, osteoporosis, spontaneous fractures, reproductive disorders, and cardiovascular disease. Alarmingly, French children remain ‘the most exposed in Europe, up to four times more than their American or German counterparts’ (URML, 2025).

This comprehensive review targets risk assessment authorities, researchers, policymakers, and agricultural organisations by examining the latest peer-reviewed evidence on cadmium exposure risks, the widespread contamination of agricultural soils — especially through phosphate fertilizer application — and current European regulatory frameworks, highlighting critical gaps. It also underscores the significantly lower cadmium accumulation associated with organic farming, suggesting a promising avenue for risk mitigation.

Human Exposure Sources to Cadmium

Human exposure to cadmium is a multifactorial phenomenon, influenced by environmental, occupational, and behavioural sources. Below are the primary absorption pathways.

1. Dietary exposure (primary pathway for the general population):

    • Bioaccumulation in the food chain: cereals, leafy vegetables (e.g., spinach, lettuce), root vegetables (e.g., potatoes), legumes, and animal-derived products (offal, crustaceans, molluscs).
    • Geochemical and agricultural factors: soils enriched with phosphate fertilisers (natural Cd contamination in phosphates) increase crop uptake.

2. Drinking water:

    • Contamination from geological sources (e.g., weathering of volcanic rocks) or industrial discharges (mining/metallurgical effluents).

3. Occupational exposure (inhalation/dermal routes):

    • High-risk sectors include metal alloy production, welding, Ni-Cd battery recycling, and the ceramics industry (glazes).

4. Tobacco smoke:

    • Bioaccumulation in tobacco: Cadmium in soil is absorbed by Nicotiana tabacumplants and inhaled via combustion (1 cigarette ≈ 0.1–0.2 µg Cd).

5. Non-occupational environmental sources:

    • Industrial emissions (e.g., waste incinerators, Zn/Pb mines), road dust from tyre wear (rubber additives).

6. Consumer products (intermittent exposure):

    • Pigments (e.g., cadmium yellow in plastics/ceramics), costume jewellery, and cosmetics (particularly those manufactured in poorly regulated markets).

Cadmium: the current public health crisis in France

The French physicians’ warning reveals alarming epidemiological trends that exemplify the global cadmium contamination crisis. According to the URML report, ‘in France, the average cadmium concentration in adults has doubled since 2007‘ and ‘in 2023, 36% of children under three years old exceeded the tolerable daily intake’ (URML, 2025). This dramatic increase in body burden reflects the multifaceted nature of cadmium exposure pathways in modern society.

The URML identified multiple contamination sources, noting that whilst cadmium occurs naturally, ‘cadmium concentrations are amplified by agricultural practices (fertilizers) and metallurgical activities‘ (URML, 2025). The heavy metal contaminates diverse food sources, including ‘bread, potatoes, vegetables, offal, crustaceans, and chocolate‘, with additional exposure occurring through inhalation amongst ‘smokers and occupationally exposed workers‘ (URML, 2025).

In response to this crisis, physicians urgently called for ‘strengthened controls, a national information campaign, medical office documentation, and implementation of recommendations from the French Agency for Food, Environmental and Occupational Health & Safety (Agence nationale de sécurité sanitaire de l’alimentation, de l’environnement et du travail, Anses)‘ (URML, 2025).

Health impacts of cadmium exposure

DNA damage and cancer risk

Cadmium is classified by the International Agency for Research on Cancer (IARC) as a Group 1 human carcinogen, with sufficient evidence linking exposure to multiple cancer types. The French physicians’ warning specifically cites associations with lung, prostate, pancreatic, liver, and kidney cancers (URML, 2025). These links are substantiated by a growing body of epidemiological and mechanistic evidence. According to Waalkes (2003), cadmium-induced carcinogenesis involves oxidative DNA damage, inhibition of DNA repair, epigenetic dysregulation, and dysfunction of tumour suppressor genes (Waalkes, 2003).

Longitudinal studies further confirm that chronic low-level cadmium exposure is significantly associated with increased cancer incidence in general populations (Adams et al., 2012). Chen et al. (2016) showed that low-dose cadmium exposure causes DNA double-strand breaks by impairing repair mechanisms in human cells, increasing genomic instability and cancer risk.

The findings support the hypothesis that cadmium’s oestrogen-like activity, disruption of DNA methylation, and persistent accumulation in key organs contribute to its carcinogenicity (Waalkes, 2003; Chen et al., 2016). These data reinforce the urgency of public health action to reduce population-wide exposure, especially through contaminated food and agricultural sources.

Cardiovascular disease risk

Recent systematic reviews and meta-analyses have established robust associations between cadmium exposure and cardiovascular disease (CVD). Whole blood concentrations of cadmium are linearly associated with risk of cardiovascular disease (CVD), whilst urinary concentrations of cadmium have a positive non-monotonic association with CVD risk (Verzelloni et al., 2024). A comprehensive dose-response meta-analysis found that when using whole blood cadmium as a biomarker, the association with overall CVD risk was linear, yielding a risk ratio (RR) of 2.58 (95 % confidence interval-CI 1.78–3.74) at 1 μg/L (Verzelloni et al., 2024).

The American Heart Association has recognised cadmium as a significant cardiovascular risk factor. Large population studies indicate that even low-level exposure to contaminant metals is near-universal and contributes to the burden of cardiovascular disease, especially heart attacks, stroke, disease of the arteries to the legs and premature death from cardiac causes (American Heart Association, 2023). Furthermore, The pooled relative risks for cardiovascular disease in men, women and never smokers were 1.29 (1.12, 1.48), 1.20 (0.92, 1.56) and 1.27 (0.97, 1.67), respectively (Tellez-Plaza et al., 2013).

Renal and bone effects

Whilst cardiovascular effects are increasingly recognised, the traditional focus on renal and bone toxicity remains relevant. Cadmium accumulates primarily in the kidneys, where it can cause tubular dysfunction characterised by increased excretion of low molecular weight proteins such as beta-2-microglobulin (B2M). The European Food Safety Authority’s assessment acknowledges these effects as critical endpoints for risk assessment.

Mechanistic pathways

In the cohort studied by Tellez-Plaza et al. (2013), established risk factors for cardiovascular disease (CVD) included male sex, older age, elevated LDL-cholesterol, reduced HDL-cholesterol, high dietary fat intake, smoking, hypertension, impaired kidney function, and diabetes. Cadmium is thought to contribute to cardiovascular damage through mechanisms such as endothelial dysfunction, oxidative stress, and disruption of calcium regulation pathways.

Regulatory framework and tolerable intakes

EFSA’s position on cadmium TDI

The European Food Safety Authority has maintained its position on cadmium exposure limits following comprehensive reassessment. The European Food Safety Authority’s Panel on contaminants in the food chain has set a reduced tolerable weekly intake (TWI) for cadmium of 2.5 micrograms per kilogram of body weight (µg/kg bw), based on an analysis of new data (EFSA, 2009).

Following an evaluation of the two approaches, the CONTAM Panel concluded that the approach adopted for its previous opinion on cadmium in food was appropriate and hence the current TWI for cadmium of 2.5 µg/kg b.w. was maintained (EFSA, 2011).

Concerning dietary exposure, average and high-level exposure were 2.3 µg/kg bw and 3.0 µg/kg bw per week respectively, with vegetarians – who eat relatively high amounts of foods containing cadmium, including cereals, nuts, oilseeds and pulses – were estimated to have an average weekly exposure of up to 5.4 µg/kg bw (EFSA, 2009).

ECHA’s regulatory approach

The European Chemicals Agency (ECHA) addresses cadmium through various regulatory mechanisms under REACH (Registration, Evaluation, Authorisation and Restriction of Chemicals) Regulation No 1907/2006.

Cadmium and its compounds are subject to restrictions under Annex XVII of REACH, with specific limitations on their use in various applications including plastics, batteries, and other consumer products.

EU regulatory framework and identified gaps

Food contaminant regulations

Food Contaminants Regulation (EU) 2023/915 sets maximum levels for lead, cadmium, mercury, and arsenic in a wide range of foods. For cadmium:

  • maximum levels range from 0.005 mg/kg in milk protein-based baby foods to 3 mg/kg in certain supplements;
  • fruit, vegetables, and fungi must not contain more than 0.02–0.5 mg/kg of cadmium,
  • the limits for meat and fish products vary from 0.05 to 1 mg/kg (Measurlabs, 2024).

Fertiliser Regulations

Fertilising Products Regulation (EU) 2019/1009 represents a significant development in controlling cadmium inputs to agricultural soils. The limits for cadmium content in ‘EC marked’ phosphate fertilisers will be 60 mg/kg as from the date of application of the regulation (European Parliament, 2018).

However, although the previous drafts of the fertilizer regulation aimed at a gradual reduction of the limit value for cadmium in P mineral fertilizer products from 60 mg/kg to 40 mg/kg P2O5 after 6 years and to 20 mg/kg P2O5 after 12 years, the Regulation (EU) 2019/1009 kept a limit value of 60 mg/kg P2O5 without approving a continued reduction plan (Marini et al., 2020).

EU regulatory gaps

Several critical gaps persist in the current EU regulatory framework:

  1. Lack of soil quality standards. Unlike water and air, soil remains largely unprotected under EU law. The European Union still lacks comprehensive soil quality standards or a binding legislative framework for soil protection, despite repeated calls for action. Notably, the proposed Soil Strategy was eventually abandoned, and recent initiatives on soil health have also faltered;
  2. Inconsistent monitoring. Whilst food products are monitored through RASFF, systematic monitoring of cadmium accumulation in agricultural soils remains fragmented across member States;
  3. Limited consideration of cumulative exposure. Current regulations tend to focus on individual exposure pathways, with insufficient attention to the cumulative body burden resulting from multiple sources. This gap is further compounded by the lack of comprehensive biomonitoring to assess real-life exposure scenarios.

Market dynamics: Moroccan phosphate exports

Morocco’s position as a dominant phosphate supplier has significant implications for cadmium exposure in Europe. Morocco possesses over 70% of the world’s phosphate rock reserves, from which the phosphorus used in fertilizers is derived (Middle East Institute, 2023). The OCP Group, Morocco’s state-owned phosphate company, has transformed the kingdom into a global fertiliser powerhouse.

Export destinations

According to recent trade data, In 2023, Morocco exported around 1.4 million metric tons of phosphate to India, one of the leading destinations of phosphate exports from the North African country, valued at approximately 234.1 million USD, whilst Mexico followed closely, importing around 2 billion MAD (roughly 203.6 million U.S. dollars) of phosphate from Morocco (Statista, 2024).

The geopolitical implications are substantial, as The EU has increased its imports of Moroccan phosphorus amid recent global supply shifts, and Morocco currently accounts for 50% of Europe’s phosphate imports (European Parliament, 2023). This dependency raises concerns given that Moroccan phosphates typically contain higher cadmium levels compared to other sources.

RASFF notifications and food safety Alerts

The EU’s Rapid Alert System for Food and Feed (RASFF) provides critical intelligence on cadmium contamination patterns. Heavy metals represent the fourth most often notified hazard category in RASFF from 1980–2016, with the highest number of notifications were related to mercury (36%), cadmium (27%), chromium (14%), lead (9%), arsenic (6%), and nickel (4%), respectively (Pigłowski, 2018).

The recent analysis by Fakhri and colleagues (2023) identified mercury (36.6%), cadmium (25.1%), and lead (14.1%) as the heavy metals most frequently reported, with 20.1% of cadmium notifications relating to cephalopods and derived products. China was the country of origin most frequently associated with food contamination notifications for arsenic, cadmium, lead, chromium, and nickel (Fakhri et al., 2023).

Organic farming: a protective approach

Contrary to the assertion that organic farming poses no cadmium risk, evidence suggests it actually provides significant protection against cadmium exposure. A comprehensive meta-analysis found that organic crops contain lower cadmium concentrations than conventional crops. Demand for organic foods is partially driven by consumers’ perceptions that they are more nutritious, and this perception appears justified regarding cadmium exposure (Barański et al., 2014).

The meta-analysis by Barański and colleagues (2014) revealed several key findings:

  1. Lower pesticide residues. The considerably higher frequency of occurrence of detectable residues in conventional fruits (75 %) than in vegetables (32 %) may indicate higher levels of crop protection inputs being used in fruit crops;
  2. Reduced heavy metal accumulation. The switch from mineral to organic fertilisers results in significant differences in metal uptake patterns, with organic systems showing lower cadmium accumulation;
  3. Systemic benefits. Organic farming induces systemic metabolic changes in crops. About 10% of proteins are differentially expressed in response to contrasting fertiliser inputs in potato and wheat, revealing core metabolic differences between organic and conventional systems (Barański et al., 2014). Frehner (2023) links these shifts to broader physiological adaptations, which may enhance nutritional quality and resilience through increased bioactive compound production.

Risk mitigation strategies

Agricultural interventions

Several strategies can reduce cadmium accumulation in crops:

  1. Soil amendments. Application of lime, biochar, biostimulants and organic matter can reduce the intake and immobilise cadmium in soil, reducing plant uptake;
  2. Crop selection and rotation. Certain crops accumulate less cadmium than others, allowing for strategic crop rotation planning;
  3. Intercropping systems. Intercropping with hyperaccumulators significantly increases heavy metal content in the hyperaccumulator and decreases metal concentrations in non-hyperaccumulator plants (Yang et al., 2016).

Policy recommendations

Based on the evidence reviewed, several policy interventions merit consideration:

  • Progressive reduction of cadmium limits. The EU should implement the originally proposed phased reduction in fertiliser cadmium limits from 60 mg/kg to 20 mg/kg P₂O₅;
  • Comprehensive soil monitoring. Establishment of an EU-wide soil monitoring network to track cadmium accumulation trends;
  • Support for organic transition. Given the demonstrated benefits of organic farming in reducing cadmium exposure, targeted support for organic conversion could yield public health benefits;
  • Enhanced traceability. Improved tracking of cadmium content in imported phosphates and fertilisers.

Interim conclusions

The accumulating evidence on cadmium’s cardiovascular toxicity at exposure levels below current regulatory limits necessitates a precautionary approach to risk management. Whilst EFSA’s TWI of 2.5 µg/kg body weight per week remains the regulatory standard, recent epidemiological data suggest health effects at lower exposures, particularly for cardiovascular outcomes. The dominance of Moroccan phosphates in EU markets, combined with their relatively high cadmium content, presents ongoing challenges for exposure reduction.

Organic farming emerges not as a source of cadmium risk, but rather as a protective factor, with meta-analytical evidence demonstrating lower cadmium concentrations in organically produced crops. This finding, combined with the broader environmental benefits of organic production, supports policies promoting organic agriculture as a public health intervention.

Future research should focus on:

  • refining dose-response relationships for cardiovascular endpoints;
  • improving biomonitoring methods to better assess cadmium body burden in exposed populations;
  • developing cost-effective cadmium removal technologies for phosphate fertilisers;
  • evaluating the long-term effectiveness of soil remediation strategies; and
  • assessing the public health impact of transitioning to lower-cadmium agricultural inputs.

Dario Dongo

Cover art copyright © 2025 Dario Dongo (AI-assisted creation)

References

Dario Dongo
+ posts

Dario Dongo, lawyer and journalist, PhD in international food law, founder of WIISE (FARE - GIFT - Food Times) and Égalité.

Related post

health benefits of organic dietThe health benefits of organic diet, scientific review nutriscore local productsNutriScore, full marks to local products. And food quality improves FoodTimes_eupha stop marketing junk foodEUPHA, stop junk food marketing aimed at children and adolescents Improving diet and public health with useful label news. EFSA opinion on nutrient profiles