Adverse health outcomes to toxic chemical exposure following a chemical disaster may be:
– effects that are local or arise at the site of contact with the chemical, such as bronchoconstriction from respiratory irritants, or irritation of the skin and eyes by gases, liquids and solids;
– effects that are systemic or affect organ systems remote from the site of absorption, such as depression of the central nervous system from inhalation of solvents, or necrosis of the liver from the inhalation of carbon tetrachloride; and
– effects on mental health arising from real or perceived releases, which depend on the psychosocial stress associated with an incident.
The time elapsing between exposure and the onset of symptoms can vary:
– Some effects, for example eye and respiratory irritation or central nervous system depression, can occur rapidly, within minutes or hours of exposure (acute effects).
– Other effects, for example cancers or congenital malformations, may take months or years to appear (long-term effects).
In PEC health impact assessment of environmental stressor will follow the so-called “full chain approach” from source to internal dose in target tissues to take into account all relevant health stressors and their interaction. This approach shifts towards a more biologically based approach for aggregate exposure assessment, dealing with the associated risks with a lower degree of uncertainty, reducing unnecessary conservatism and allowing for a more comprehensive cost/benefit analysis and efficient risk management.