Source reconstruction of airborne toxics based on acute health effects information

Christos D Argyropoulos,Eleni Fthenou,Alexandros Venetsanos,Samar Elkhalifa,Spyros Andronopoulos,Konstantinos E Kakosimos,George C Efthimiou,Ivan V Kovalets

doi:10.1038/s41598-018-23767-8

Abstract

The intentional or accidental release of airborne toxics poses great risk to the public health. During these incidents, the greatest factor of uncertainty is related to the location and rate of released substance, therefore, an information of high importance for emergency preparedness and response plans. A novel computational algorithm is proposed to estimate, efficiently, the location and release rate of an airborne toxic substance source based on health effects observations; data that can be readily available, in a real accident, contrary to actual measurements. The algorithm is demonstrated by deploying a semi-empirical dispersion model and Monte Carlo sampling on a simplified scenario. Input data are collected at varying receptor points for toxics concentrations (C; standard approach) and two new types: toxic load (TL) and health effects (HE; four levels). Estimated source characteristics are compared with scenario values. The use of TL required the least number of receptor points to estimate the release rate, and demonstrated the highest probability (>90%). HE required more receptor points, than C, but with lesser deviations while probability was comparable, if not better. Finally, the algorithm assessed very accurately the source location when using C and TL with comparable confidence, but HE demonstrated significantly lower confidence.

Highlights

In modern societies, where risk has a dominant role in all facets of our life[1,2], short-term exposure to toxic/ hazardous material (HazMat), whether intentional or accidental, poses great threats to the surrounding population[3,4,5]
An unlikely event of a toxic/hazardous material begins with a “source” releasing the HazMat in the air, depending on the meteorological conditions, the plume is dispersed reaching, potentially, high HazMat “concentrations” that vary over space and time
With the use of health effects (HE) as input parameter the performance of the method improves with significantly reduced variability compared to the C input data

Summary

Introduction

In modern societies, where risk has a dominant role in all facets of our life[1,2], short-term exposure to toxic/ hazardous material (HazMat), whether intentional or accidental, poses great threats to the surrounding population[3,4,5]. The subject’s “response” to the HazMat event will be exhibited by a series of adaptive or adverse health effects This is the consequences analysis paradigm[10] in which the final impact of a HazMat release depends on the “source-concentration-exposure-dose-response” binary relationships. The reconstruction of the source term of an airborne contaminant may be obtained by using forward (optimization/minimization) or backward (inverse) approaches, in which source characteristics are inferred from concentration or deposition measurements at different locations and time intervals by establishing source-receptor (i.e. source-concentration) relationships[15]. Other researchers[45] moved one step further by using Physiologically Based Toxicokinetic (PBTK) and Biologically Based Dose-Response (BBDR) models, together with appropriate optimisation and inverse modelling techniques to reconstruct exposure to environmental chemicals, and to some extent the source itself, from biomarkers. In the same direction, simplified PBTK models and clinical data were deployed to demonstrate the reconstruction of exposures, to BisPhenol A51 and Carbaryl[52]

Methods

Results

Discussion

Conclusion