Toxic Metals in a Superfood? What Maca Reveals About Mining and Health in Peru

Redacción HC
26/05/2023

In Peru's central highlands, a silent threat is growing beneath the soil. While the Andean crop maca (Lepidium meyenii) is hailed worldwide for its nutritional and medicinal properties, new research reveals an unsettling truth: this "superfood" may be contaminated with toxic metals from nearby mining activity.

A recent study published in Toxicology Reports investigates the presence of heavy metals in the soil and edible tissues of maca grown near mining zones. The findings raise pressing concerns about food safety, public health, and environmental justice in one of the world’s richest mineral regions.

Mining, Agriculture, and Contamination: The Research Question

Heavy metal pollution is a well-documented consequence of extractive industries. These contaminants persist in soil, accumulate in crops, and eventually enter the human food chain. In central Peru, intensive mining has long shaped the landscape—and the risk it poses to agriculture is just beginning to surface.

This study asks: To what extent are maca crops contaminated by heavy metals, and what are the associated health risks for consumers? By analyzing soil and plant samples from three districts in Junín province, the researchers aim to assess levels of arsenic (As), cadmium (Cd), lead (Pb), iron (Fe), and zinc (Zn), and estimate the risks posed to local populations.

Methodology: Measuring Metal Uptake and Human Risk

The research team collected maca roots and soil samples from three Peruvian districts with a history of mining and smelting operations. They used atomic absorption spectrophotometry to determine metal concentrations in both soil and plant tissues.

To assess how much metal the maca absorbs from the soil, the study calculated the bioconcentration factor (BCF) for each element. A BCF less than 1 indicates low uptake.

They also applied standard toxicological models to estimate:

• Estimated Daily Intake (EDI) for each metal
• Hazard Quotient (HQ) and Hazard Index (HI) for non-carcinogenic risks
• Cancer Risk (CR) estimates for arsenic, cadmium, and lead

These calculations followed health risk thresholds established by global agencies like the FAO/WHO.

Key Findings: Some Metals Exceed Safe Limits

The results reveal a mixed picture:

• Cadmium (Cd) and lead (Pb) concentrations in maca exceeded safety limits set by FAO/WHO, with mean values of 0.32 mg/kg and 0.20 mg/kg respectively.
• The BCF was below 1 for all metals, meaning the maca does not strongly accumulate heavy metals from the soil.
• Non-carcinogenic risk indicators (HQ and HI) were below 1, suggesting that regular consumption of maca is unlikely to cause immediate health effects.
• However, the cancer risk (CR) values for arsenic and cadmium exceeded acceptable thresholds—particularly concerning for children.
• In Ondores district, the CR for arsenic in children surpassed the U.S. EPA benchmark of 1×10⁻⁴, indicating a potentially significant long-term risk.

“Even though maca doesn’t accumulate metals efficiently, persistent contamination in the soil is enough to pose a threat,” the study concludes.

Why It Matters: Food Safety and Environmental Justice

The study highlights the urgent need for systematic monitoring of crops grown near mining operations. While maca remains an important economic and cultural crop in Peru, its safety must be ensured—especially for communities consuming it as part of their staple diet.

Key policy and public health implications:

• Soil remediation in mining-affected regions must become a national priority.
• Routine testing of agricultural products in high-risk zones is essential.
• Health risk assessments should be included in environmental licensing processes for mining companies.
• Research should expand to include other ecotypes of maca and different crop varieties, as metal uptake can vary between plant strains.

The authors emphasize that although the current non-carcinogenic risk is low, the elevated cancer risk in children warrants immediate attention.

Maca Under Threat: A Symbolic Crop Faces Modern Challenges

Maca is more than just a superfood—it is a symbol of resilience and heritage in the Andean highlands. Yet this revered plant now sits at the intersection of agriculture, industry, and public health.

For Peru, the findings underscore the delicate balance between economic development and environmental responsibility. The country’s rich mineral resources must be managed with greater care, especially when they intersect with food production and community wellbeing.

Conclusion: Turning Science into Policy

This research serves as a vital warning. Contamination from mining does not stay confined to tailings ponds—it seeps into the soil, enters crops, and eventually, our bodies. As the authors note, “a crop that symbolizes health and vitality may now carry hidden risks.”

To ensure that maca remains safe, sustainable, and export-worthy, Peru and other mining nations must strengthen environmental oversight, invest in soil health, and prioritize the voices of affected communities.

Let this be a call to action: protecting the safety of our food begins with protecting the soil beneath our feet.

Topics of interest

Pollution Health