Content of Toxic Elements (Arsenic, Cadmium, Mercury, Lead) in Eggs from an Ethically Managed Laying Hen Farm

TL;DR

This study compares toxic element levels in eggs from an ethical farm and supermarket eggs, finding higher contamination in supermarket eggs.

Contribution

The study provides new data on heavy metal contamination in eggs from ethical farming versus supermarket sources.

Findings

Supermarket egg albumens were significantly more contaminated with lead than rural eggs.

Arsenic levels were higher in rural egg albumen and eggshells compared to supermarket eggs.

Cadmium and mercury contents were below or near the limit of quantification in all samples.

Abstract

Eggs are a valuable source of nutrients, including proteins, fats, vitamins, and minerals. Moreover, they are also a healthy, nutritious, and easily digestible food. In the last decade, the rearing of chickens at home has been promoted and spread in several Italian communities and throughout the world as a means of promoting the self-consumption of home-produced food. These interventions have been successful because chickens are friendly and colourful pets, and they are inexpensive to buy and feed. However, backyard chickens are potentially exposed to different types of contaminants, such as heavy metals, pesticides, and other chemicals, due to their free access to the natural environment. This study focuses on the presence of four toxic elements in eggs from free-range hens raised in a large park and organic eggs bought at the supermarket.

Domestic chicken farming has been promoted and spread in several Italian municipalities and worldwide as an aid to the self-consumption of domestically produced food. This study investigated the levels of four toxic elements (As, Cd, Hg, and Pb) in eggs from an ethical laying hen farm, comparing the element concentrations with those possibly present in supermarket eggs. A total of 201 eggs, 141 from the farm and produced by different hen genotypes, and 60 from the supermarket, were collected. The levels of the toxic elements were evaluated in the yolk, albumen, and eggshells of all eggs. The results show that the supermarket eggs’ yolk and albumen were more contaminated with lead, compared to the rural eggs. Contrarily, the mean content of arsenic was higher in the albumen and eggshells of the rural eggs, compared to the supermarket eggs. The cadmium content was below the LOQ (0.005 mg/kg) in all samples. The mercury content was below or around the LOQ in all rural eggs. Overall, the supermarket egg albumens were significantly more contaminated than the rural ones. No significant differences were found in quality parameters for both types of eggs. The toxic element values that were detected were in line with other studies in the literature. However, despite the concentrations found not representing a risk to the consumers’ health, the results of this study raise a potential food safety issue, and it would be desirable to set specific MRLs for eggs for consumers’ protection.