High Cadmium Levels Detected in Mexico City Foods

A recent study conducted by a group of Mexican researchers revealed the presence of high concentrations of cadmium in foods sold in Mexico City. Exposure to this heavy metal could particularly affect children due to their higher absorption rates and lower detoxification capacities. 

The study, Dietary Risk Assessment of Cadmium Exposure Through Commonly Consumed Foodstuffs in Mexico, conducted between April 2022 and January 2023 by various research centers and universities including UNAM and IBERO, found that some foods sampled in Mexico City showed elevated cadmium concentrations. 

Cadmium is a heavy metal classified as a carcinogen. It can accumulate in the body and cause chronic problems in organs such as the kidneys, lungs, and bones. According to the National Cancer Institute, cadmium is an environmental contaminant naturally present in the environment, primarily in soils and rocks.

The foods selected for the study were based on data from the 2018 National Health and Nutrition Survey (ENSANUT) and prior studies identifying potential sources of the metal. The research included an estimate of the theoretical weekly intake of cadmium, using recommended portion sizes outlined in the Healthy and Sustainable Dietary Guidelines for the Mexican population, adapted by age and gender.

A total of 143 food items were analyzed, and 68.5% displayed detectable cadmium concentrations. Among food groups, vegetables exhibited the highest mean levels, averaging 0.084 mg/kg, followed closely by snacks, sweets, and desserts at 0.049 mg/kg, fruits at 0.037 mg/kg, condiments and spices at 0.028 mg/kg, and cereals recording 0.026 mg/kg. Overall, crop-based foods such as oyster mushrooms with 0.575 mg/kg, romaine lettuce with 0.335 mg/kg, and cocoa powder with 0.289 mg/kg, presented the highest metal concentrations. 

The study’s findings highlighted that cadmium’s presence is especially concerning for school-aged children due to their higher absorption rates and limited detoxification capacities. In this age group, the estimated weekly intake reached 3.83µg/kg of body weight, exceeding the tolerable limit of 2.5µg/kg established by institutions like FAO and WHO, by 53.2%. In contrast, intake among adults and adolescents was below the limit, at 1.80µg/kg and 2.05µg/kg, respectively.

Alejandra Cantoral, Researcher, IBERO’s Department of Health and one of the study’s authors, explained that cadmium contamination primarily stems from polluted agricultural soils. According to Cantoral, the element reaches these soils through waste generated by human activities, particularly industrial processes. 

Cantoral emphasized that one of the main sources of soil contamination is recycling plants, especially those handling batteries. She stressed the importance of enforcing regulations to prevent cadmium from being released into the environment, noting that once in the soil, it can remain for hundreds of years. Furthermore, she pointed out that globally, cereal crops like rice and wheat have been identified as major sources of exposure.

The study calls on food authorities to intensify monitoring in foods to identify contaminated regions and design soil remediation plans. It also underscores that responsibility lies not only with farmers but also with governments and regulatory agencies, which must strengthen measures to protect public health.