Lead exposure to children from consumption of backyard chicken eggs

Abstract

Backyard chicken ownership is rapidly increasing in urban areas in the United States, largely as a way to provide eggs for household consumption. Despite elevated levels of environmental lead contamination in many US cities, the role of backyard chicken eggs as a pathway for lead exposure, particularly for children, has received limited scrutiny. To characterize lead exposure from consumption of backyard chicken eggs for children and predict related effects on blood lead level (BLL), we conducted a cross-sectional study of backyard chicken owners in the Greater Boston area (n = 51). We interviewed participants regarding egg consumption by household members and collected backyard eggs (n = 201) and coop soil samples (n = 48) for analysis. Inductively coupled plasma mass spectrometry (ICP-MS) was used to evaluate lead concentration in homogenized eggs and an X-ray fluorescence (XRF) portable device was used to assess soil lead levels in the laboratory. We used the USEPA's Integrated Exposure Uptake Biokinetic Model for Lead in Children (IEUBK) to assess the relative contribution of backyard egg consumption to aggregate BLL in children. Four scenarios were developed in the IEUBK model to address variability in egg consumption rates and egg lead contamination. Lead was detected in egg samples from 98% of the households that provided egg samples. Mean household lead concentration was 0.10 μg/g (SD: 0.18). Egg lead concentrations ranged from below the limit of detection (0.0014 μg/g) to 1.798 μg/g (<1.4-1198 ppb). Egg lead levels were strongly positively correlated with lead concentration in coop soil (r = 0.64; p < 0.001). In modeled scenarios where a child < 7 years frequently ate eggs highly contaminated with lead, BLLs are predicted to increase by 0.9-1.5 μg/dL. In three other scenarios reflecting more moderate egg lead contamination and consumption rates, BLLs were predicted to increase from 0.1 to 0.8 μg/dL. Consumption of backyard chicken eggs can contribute to lead exposure in children. Soil lead remediation prior to chicken ownership may reduce lead exposure from backyard eggs.

Causes of mortality in backyard poultry in eight states in the United States

“…Given that exposure to lead via consumption of eggs is a significant human health threat, this finding is concerning, and flock owners, primarily pregnant women and children who are consuming eggs, should be advised of this risk and of routine testing options. 3,24,39 Most of the additional toxin-related mortalities were preventable, including rodenticide, insecticide, and ionophore exposures, and medication overdoses. One case of botulism involved the mortality of 14 chickens that had access to pecking on a backyard compost pile, which poses a newly described threat for backyard flock owners.…”

Potential contaminants and hazards in alternative chicken bedding materials and proposed guidance levels: a review

“…Consumption of chips of Pb-based paint peeling from a chicken house was associated to acute poisoning of laying hens ( Trampel et al., 2003 ), whereas chronic exposure to Pb-contaminated soil has been implicated in subclinical exposure of backyard flocks ( Leibler et al., 2018 ; Mordarski et al., 2018 ). Clinical signs of acute Pb poisoning in chickens include muscle weakness, ataxia, and loss of appetite, followed by marked weight loss and eventual cessation of egg production.…”

Sub-chronic treatment with high doses of ascorbic acid reduces lead levels in hen eggs intentionally exposed to a concentrated source of lead: a pilot study

“…It has been suggested that after ingestion by hens, heavy metals can deposit in different tissues including eggs laid by hens exposed to pollution [2,8]. Therefore, assessing foods for potentially harmful toxic metals has been recently recognized as an important health issue because exposure to heavy metals can be harmful to the health of children and adults [9,10].…”

“…Increasing exposure to environmental lead has been attributed to recent industrialization and urbanization in some regions [13,14]. Recent studies have shown that plants and grains grown upon soils contaminated with lead contained elevated levels of this toxic heavy metal [10,15,16]. Therefore, it would not be surprising that birds and animals grazing on contaminated grains would be found to have elevated levels of this toxic heavy metal [6,17].…”

“…Lead would probably be deposited in various tissues including eggs laid by birds exposed to environmental lead [18,19]. Ingestion of lead contaminated hen eggs can increase lead levels in children and adults [10]. A recent study conducted on breastfeeding women from the West Bank of Palestine showed that about 19% of the breast milk samples analyzed contained lead levels above those recommended by the World Health Organization (WHO) [14].…”