Lead Exposure From Backyard Chicken Eggs

Did you know there is a risk of lead exposure from backyard chicken eggs? This is especially true with children.

Chickens have become all the rage all around the country. They are cute, fairly easy to care for, and provide breakfast some at a very young age for several years. What could be any better? This ever-growing popular backyard friend comes with associated risks that we often talk about here at Make Food Safe, but there is a concern that lead can be present in backyard chicken eggs leading to lead exposure in children.

The increase in poultry ownership in urban areas with heightened environmental lead contamination compels an investigation into backyard egg consumption as a source of lead exposure, particularly for children.

Environmental lead contamination is ubiquitous in the United States due to the historical use of leaded gasoline and paint. A well-established literature documents the association between exposure to lead contaminated paint, dust, and soil and elevated blood lead levels in children. Urban gardening is a documented source of lead exposure, both from accidental ingestion of leaded soil and from uptake or adherence of leaded soil on produce. Environmental lead exposure is associated with neurological impairment in children, including reduced IQ, as well as attention-related behavior problems and reduced academic achievement, at increasingly low levels of exposure. According to the US Centers for Disease and Prevention, there is no safe blood lead level for children, indicating that any source of exposure poses health risks.

In addition to consumption of contaminated eggs, human caretakers of chickens may be exposed to lead in soil from incidental ingestion of soil following bird handling or outdoor activity in the yard. Poultry owners may also inhale lead contaminated dust while caretaking or playing with birds, and may track contaminated soil into the home. In poultry, lead is preferentially deposited in the eggshell and egg yolk over the albumin, and lead is excreted in the feces.

Chickens are exposed to lead in contaminated soil through poultry behaviors, such as foraging, roosting, preening, fighting, and dust bathing. Chickens may also be exposed to lead through their diet; lead bio-accumulates in some chicken feeds and supplements, including worms and invertebrates and bone meal and oyster shells. While the full depiction of the chicken-human lead pathway in the context of backyard chicken production is beyond the scope of this paper, we note that egg consumption is likely one of multiple pathways of potential lead exposure associated with backyard poultry husbandry. A limited number of studies have documented detectable levels of lead in backyard eggs to date, including lead concentrations higher than detected in commercially-available eggs.

The Study Details:

Fifty-one households participated in the study, with 50 households completed the questionnaire and 48 households provided egg samples, ranging from 1–12 eggs (total of 201 eggs collected). Forty-eight households provided coop soil samples. Mean household size was 3.8 persons. Approximately 40% (n=19) of households had children younger than seven years old in the home, of which the majority (n=17) had children younger than 3 years (89% of households with children and 35% of total households had children younger than 3 years). Households kept chickens on their properties from two months to nine years. Households owned a mean of six chickens at the time of the study, and chickens collectively produced on average 26 eggs per week per household (range 8–68). In our modeling, we assumed this rate of production continued over a 37 week laying season given the seasonal factors noted above.

We observed detectable lead concentrations in backyard chicken eggs collected in the Greater Boston area. Our IEUBK modeled scenarios predicted increases in children’s BLL associated with backyard egg consumption ranging from 0.1to 1.5 ug/dL. Our maximum consumption scenario indicates that consuming backyard chicken eggs may increase BLL by as much as 50% for infants <1 year. In our maximum exposure scenario, all children younger than 6 years had increases in BLL resultant from backyard egg consumption ≥1 ug/dL. Our findings indicate that chicken eggs may be a source of lead exposure children whose families raise backyard chickens and consume their eggs.

There is currently considerable interest in establishing the dose-response relationship between particular exposures, including food, water, soil and dust, and blood lead levels in children as a tool for public health interventions.

Lead contamination of backyard chicken eggs was nearly universal in our study of backyard chicken owners in the Boston area. Egg lead concentration was highly correlated with backyard soil lead levels from the coop, indicating environmental contamination. Consumption of backyard eggs contributed to increases in predicted BLLs for children younger than 7 years ranging from 0.1–1.5 ug/dL. We observed the greatest predicted relative contribution of backyard eggs to BLL among young children <1 year old. In light of the growing popularity of backyard chicken ownership, this understudied pathway of lead exposure warrants further scrutiny.

While many people who own backyard chickens are in very rural areas, the consideration that this study took place in urban areas raises eyebrows to make us wonder how much lead is present in the rural areas where old farm homeplaces exist and where children often reside in homes that are very dated. This is definitely something to consider should your child test with high lead levels which happens more frequently than in recent years in our rural area.

Keep an eye on Make Food Safe for more information about studies similar to this one and many more.