Starting an Assessment (Text Version)

The three main elements — source and exposure, the ecosystem at risk, and the ecological effects — must all be identified, but any of them may be the reason for starting the assessment:

1. There may be an existing or proposed source whose potential effects you want to know.
2. There may be a specific resource you want to protect; you may be trying to identify potential threats so you can focus protection or pollution-prevention efforts.
3. Effects may have been observed; you may be conducting the assessment retrospectively to figure out what might have caused them.
   

Review each example of why a risk assessment might be initiated.

For a Superfund ERA or PMN (OPPT premanufacture notice), the risk assessment is stressor-based.

Assessors start with data on stressors and sources.

They seek data on:

• Exposure pathways.
• Effects on susceptible entities/organisms.

For a watershed analysis, the risk assessment is resource-based.

Assessors start with data on the affected ecosystem/organism (resource or receptor).

They seek data on:

• Potential stressors and sources.
• Potential effects.
• Additional organism and ecosystem characteristics.

For fish kills, the risk assessment is effect-based.

Assessors start with data on observed effects.

They seek data on:

• Stressors that could have caused the effect.
• Potential sources of those stressors.
• Repercussions in addition to fish death (effects on otters? great blue herons?).