A note on the three-period two-treatment crossover designs

Abstract

Assessment of the health impacts related to hazardous waste is a major scientific challenge with multiple societal implications. Most studies related to associations between hazardous waste and public health do not provide established of mechanistic links between environmental exposure and disease burden, resulting in ineffective waste management options. The exposome concept comes to overhaul the nature vs. nurture paradigm and embraces a world of dynamic interactions between environmental exposures, endogenous exposures and genetic expression in humans. In this context, the exposome paradigm provides a novel tool for holistic hazardous waste management. Waste streams and the related contamination of environmental media are not viewed in isolation, but rather as components of the expotype, the vector of exposures an individual is exposed to over time. Thus, a multi-route and multi-pathway exposure estimation can be performed setting a realistic basis for integrated health risk assessment. Waste management practices are thus assessed not only regarding their technological edge and efficacy but also their effects on human health at the individual and community level, considering intra-subject variability in the affected population. The effectiveness of the exposome approach is demonstrated in the case of Athens, the capital of Greece, where the health effects associated to long term and short term exposure to two major waste management facilities (landfill and plastic recycling) are presented. Using the exposome analysis tools, we confirmed that proximity to a landfill is critical for children neurodevelopment. However, this effect is significantly modified by parameters such as parental education level, socioeconomic status and nutrition. Proximity to a plastics recycling plant does not pose significant threats under normal operating conditions; yet, in the case of an accidental fire, release of persistent carcinogenic compounds (dioxins and furans) even for a short period results in increased lifelong risk, especially for breast feeding neonates.