ERA

Question 1

What are the steps of ERA?

Answer 1

Hazard identification
Exposure assessment
Effect assessment
Risk characterization

Question 2

Hazard identification

Answer 2

Identification of stressors and endpoints are central. The adverse effects that a substance has an inherent capacity to cause are identified. This involves gathering and evaluating data on the types of health effects or disease that may be produced by a chemical and exposure conditions under which environmental damage, injury or disease will be produced. Hazard identification may also involve characterization of the behavior of a chemical within the body and its interactions with organs, cells or genetic material.

Question 3

Exposure assessment

Answer 3

Exposure can be assessed by measuring exposure concentrations, once chemicals are produced, used and emitted. Regarding new chemicals, one can only predict. This involves estimating emissions, pathways and rate of movement of a substance and its transformation or degradation in order to obtain concentrations or doses to which human populations or environmental compartments are or may be exposed. The evaluation may concern past or current exposures or anticipated future exposures. The lack of information on emission factors during the production of chemicals (point-source pollution) and the use of chemicals in various products and their emissions causes this part to be uncertain. Other things that contribute to this uncertainty is the enormous geographic variability due to differences in abiotic conditions such as climate, hydrology, geology and biotic conditions. In this step, the PEC (predicted environmental concentration) or human intake is determined.

Question 4

Effects assessment

Answer 4

This also goes under the name dose-response assessment and is the estimation of the relationship between dose or level of exposure to a substance, and the incidence and severity of an effect. Sometimes it involves the description of the quantitative relationship between the degree of exposure to a substance and the extent of a toxic effect or disease, but reliable quantitative precision cannot always be achieved. The data is usually obtained from structure-activity relationships, in vitro studies, plant and animal laboratory studies and sometimes field studies.
No effect levels derived from laboratory studies in animals are usually converted to NELs for humans of the environment by applying assessment factors (10-10000). In this step, the
DNEL (derived no effect level) or PNEC (predicted no effect concentration) is determined.

Question 5

Risk characterization

Answer 5

The estimation of the incidence and severity of the adverse effects likely to occur in a human population or environmental compartment due to actual or predicted exposure to a substance. A framework to define the significance of the risk developed, and all the assumptions, uncertainties and scientific judgements from the preceding three steps are considered. Risks are often expressed as PEC/PNEC ratios for the environment and for human risks a similar comparison between exposure and NEL is usually made. In this step we may provide a relative risk ranking. This ranking enables us to compare single chemicals or groups of chemicals once the risks of the respective chemicals have been assessed in a consistent simplifies manner.