Bisphenol A (BPA) is an industrial chemical widely used in polycarbonate plastics and epoxy resins, making it a high-volume chemical found in numerous consumer products. BPA functions as an endocrine-disrupting chemical, interfering with the body’s hormonal system by mimicking or blocking natural hormones. Since hormones regulate functions from metabolism to development, the widespread presence of BPA raises concerns across all age groups. However, the risk associated with this exposure is not uniform, as different age groups experience distinct exposure profiles and vulnerabilities.
Infants and Toddlers: The Highest Relative Exposure Risk
Infants and toddlers (0 to 2 years old) face the highest relative exposure risk to Bisphenol A. This high risk is due to the dose of the chemical received relative to their small body weight, resulting in a significantly higher concentration per kilogram than in older children or adults. Historically, a major route of exposure was formula or milk in polycarbonate baby bottles, especially when heated. Although BPA use in baby bottles is banned in many regions, exposure continues through sources like the lining of canned liquid infant formula.
This age group also exhibits unique behavioral exposure pathways. Extensive hand-to-mouth activity facilitates the ingestion of BPA present in dust and consumer products as toddlers frequently mouth toys and surfaces. Furthermore, the metabolic capacity of infants is immature, meaning their liver’s detoxification pathways are not fully developed. The slower functioning of the glucuronidation pathway increases the time the active chemical remains in the system compared to adults.
Changing Exposure Dynamics in Older Children and Adolescents
As children transition into the 3- to 17-year age bracket, BPA exposure dynamics shift significantly. The primary behavioral route of exposure, such as mouthing objects, decreases notably. The dominant source of exposure for this older group becomes the diet, mainly through packaged and canned foods where BPA is used in the protective epoxy resin lining.
While the absolute amount of BPA ingested may increase due to higher food consumption, the relative exposure per kilogram of body weight generally declines compared to infancy. This decline is attributed to a substantial increase in body mass, which dilutes the chemical’s concentration. Additionally, the metabolic systems of older children are more mature, allowing for more efficient detoxification and elimination of BPA. Exposure can also occur through handling thermal paper receipts, which contain high concentrations of the chemical.
Adult Exposure Profiles and Occupational Risks
For the general adult population, the majority of BPA exposure occurs through the diet, primarily from the migration of the chemical from food packaging and the resin linings of metal food and beverage cans. Adults exhibit a greater total intake of the chemical compared to infants due to their larger body size and higher food consumption. Despite this higher absolute exposure, their relative risk is lower than that of infants and toddlers.
Adults possess a fully developed and highly efficient metabolic system, particularly the glucuronidation pathway in the liver. This pathway rapidly conjugates BPA, converting it into an inactive form that is quickly excreted in the urine, leading to a half-life measured in hours. A notable exception is occupational exposure, particularly for workers such as cashiers who frequently handle thermal receipt paper. The high concentration of BPA in this paper can be absorbed through the skin, leading to chronic exposure that bypasses the primary digestive metabolism route.
Developmental Vulnerability and Health Implications
The heightened relative exposure risk in infants and toddlers is significant because it coincides with a period of extreme developmental vulnerability. Exposure to endocrine-disrupting chemicals like BPA during the prenatal and early postnatal periods occurs during “critical windows of development.” These are specific, sensitive timeframes when hormonal signaling is crucial for the proper formation and organization of the neurological, reproductive, and metabolic systems. Interference during these windows can have lasting consequences that may not manifest until years later, such as during puberty or adulthood.
BPA acts as a xenoestrogen, mimicking the body’s natural estrogen, which disrupts the delicate balance of hormone-regulated development. Studies have suggested links between early life BPA exposure and various outcomes, including neurobehavioral issues such as hyperactivity and attention problems, as well as altered reproductive and metabolic function. The fact that the highest relative dose is delivered to the most sensitive population underscores why infants and toddlers are considered the age group facing the most significant potential hazard.