Understanding the Exposome
The Role of Life Course
The period of childhood may be viewed as a succession of phases or stages with distinguishable anatomical, physiological, and psychological characteristics. A child’s exposure and vulnerability to internal, social and physical components vary over developmental phases, ranging from preconception, fetal period, neonatal period, infant, toddler, early childhood, middle childhood and early and late adolescence.
Over these time periods children are subjected to a wide diversity of physical and social exposures in places and times, exposures over which they have little control. A child’s individual vulnerability varies due to their extensive bio-psycho-social development. Children also have a comparatively higher uptake of substances due to their physiology and less developed detoxification metabolism.
Prenatal
0-3
3-6
7-12
Adolescent
How do social practices, exposures, and the environment shape child development and become more complex over time?
The environment in which the individual is embedded includes a range of social, physical, and internal exposures.The life course highlights the need to consider child development as a crucial aspect in the articulation of social practices and exposures in connection to places, actors, and activities. This perspective emphasizes the dynamic and interconnected nature of development, where the experiences and interactions a child has within their environment play a significant role in shaping their growth.
These exposures are not static; they evolve and become more complex as the individual progresses through different stages of life. Understanding this complexity is essential for addressing the varied influences on development and for creating supportive environments that foster healthy growth and development throughout the entire life course but especially throughout child’s development.

How do key stages in child development affect how vulnerability, susceptibility, and equity are considered in a child's view of the exposome?
To adopt a child perspective to the exposome, we explore the concepts of vulnerability, including the notions of susceptibility and equity.
This perspective acknowledges that children are uniquely vulnerable to various exposures due to their ongoing development and growth. In particular, brain development is a critical focus, as it undergoes extensive changes during childhood.
We would like to understand how these changes make children especially susceptible to environmental influences during specific critical periods.
These critical periods are time windows when the brain is particularly sensitive to external factors, which can have lasting effects on cognitive, emotional, and physical development. By incorporating the concepts of vulnerability and susceptibility, we emphasize the importance of equitable interventions and protective measures to support healthy development during these crucial stages. This child-centric approach to the exposome highlights the need for policies and practices that address the unique needs and challenges faced by children, ensuring their environments promote optimal growth and development.
How does the cumulative effect of various exposures influence long-term mental health/well-being and cognitive development in children?
The cumulative effect can be explained by examining how the various exposures and experiences a child encounters throughout their development can add up short-term over time, influencing the degree of significant long-term impacts on their mental health and well-being. In the framework of the exposome, the cumulative effect refers to the way in which repeated or sustained exposures—whether social, physical, or internal—interact with one another and with the child's developmental stages.
During critical periods of brain development, for instance, the child is particularly sensitive to environmental influences. Exposures to factors such as pollution, social stressors, or inadequate nutrition during these times can have immediate effects on development. However, the cumulative effect emphasizes that these exposures do not occur in isolation. Instead, they build up over time, with early exposures potentially making the child more susceptible to later ones. This accumulation can amplify the overall impact on the child's development, leading to more pronounced effects on their cognitive, emotional, and physical health.
Moreover, the cumulative effect highlights the importance of considering equity in the exposome framework. Children from disadvantaged backgrounds may face a higher burden of negative exposures, such as poor living conditions or limited access to healthcare, which can accumulate and exacerbate vulnerabilities. By recognizing the cumulative nature of these exposures, interventions can be better designed to address and mitigate these compounded risks, promoting more equitable outcomes for all children.