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26 Cards in this Set

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• What is the purpose of ecological risk assessments?

o They help risk managers determine which course of action to take for ecosystems that have been or could be exposed to stressors

• What are the steps for ecological risk assessment?

o Planning, which leads to problem formulation. From there we go to analysis to characterize the exposure and ecological effects. Next is risk characterization. Lastly we communicate the results and manage the risk. As needed, we gather data and monitor.

• What questions does problem formulation address?

o What problem(s) are we addressing? What is the best ecological focus for the risk assessment? How should we approach this assessment?

• What are the results of the analysis in the ecological risk assessment used to do?

o Estimate and describe the ecological risk, indicate the overall degree of confidence in the risk estimates, cite evidence supporting the risk estimates, and interpret the adversity of the ecological effects. It could be expressed quantitatively or qualitatively.

• What are the differences between human health and ecological risk assessments?

o Ecological risk assessments involve multiple organisms that are unevenly understood.
o Ecosystems are not necessarily viewed as very important b/c some care less about other organisms and there are many views about which organisms to protect.
o Not everyone agrees on what is good or bad for the environment.
o It is generally the opposite for human health assessments

• How are some ecological stressors distributed through the environment?

o It can reach the food chain through sediment, soil, and surface waters. It can also get into the environment, be sent to treatment plants or down the drain from our homes. They can easily travel to the food chain.

• When is a substance classified as persistent? How is this measured?

o When the substance in a given medium resists physical, biological and chemical degradation.
o The degradation of a substance in a given medium is usually expressed by its overall half-life

• When does a substance fulfill its persistent criterion (P) in marine water, fresh/estuarine water, marine sediment, fresh/estuarine sediment, and soil?

o Marine water – half life greater than 60 days
o Fresh water – half-life greater than 40 days
o Marine sed. – half-life greater than 180 days
o Fresh sed. – half-life greater than 120 days
o Soil – half-life greater than 120 days

• What is bioaccumulation? What is it expressed by?

o It is the capacity of a substance to accumulate in the tissues of organisms either through direct exposure to water/air/soil, or through consumption of food.
o It is expressed by the ratio of its concentration in the organism to the concentration in the medium to which the organism is exposed (bioaccumulation factor BAF)

• What is BCF and BMF?

o BCF a.k.a. bioconcentration factor is when the chemical intake in the organism is through the substance dissolved in the medium (generally water)
o BMF a.k.a. biomagnifications factor is when the intake is via food.

• When does a substance fulfill the bioaccumulation criterion (B)?

o When the BCF is higher than 2000

• How is toxicity measured?

o It is measured in a series of concentration-response experiments on various organisms and endpoints over various exposure periods. Threshold values are given to establish whether or not a chemical presents a toxic hazard.
o The toxicity is compared to potential exposure of chemical in medium to determine the environmental risk.

• Which are more relevant for assessing potential effects in environment, chronic or acute studies?

o Chronic because certain chemicals have the potential to persist longer in the environment.

• How does a substance fulfill the toxicity criterion (T)?

o The NOEC (long term no observed effect concentration) for a marine or freshwater organism is less than .01 mg/l
o The substance is classified as a carcinogen (cat. 1 or 2), a mutagen (cat. 1 or 2), or toxic for reproduction (cat. 1, 2, or 3).
o There is no evidence of chronic toxicity as identified by certain classifications.

• What is a Predicted exposure concentration (PEC)?

o It is an estimate of the exposure assessment of new substances. The calculations are made by using exposure models and realistic predictions of anticipated market volume of product.

• What is the most important compartments of the PEC for consumer products?

o Water and soil

• How is exposure characterization calculated?

o Calculate per capita usage and wastewater concentration, estimate the removal in treatment, apply the dilution factor, and calculate the PEC.

• What is the Predicted No Exposure Concentration (PNEC) value? What organisms are used for the different environments?

o It is the assessment of the toxicity of the ingredient to certain environmental indicator species.
o For aq. Environments, indicator species are freshwater fish, invertebrates, and green algae.
o For sediemnts and soils, indicator species are sediment dwelling organisms like earthworms and plants.
o For air, the indicator species are birds.

• Where is toxicity data for environmental indicator species obtained from? What are they used for?

o From literature or lab testing. In some cases we use quantitative structure activity relationships (QSARS) for low volume/low toxicity ingredients.
o They’re used to divide the lowest available effect level or NOEL to derive a PNEC for the ecosystem.

• What are the assessment factors for the derivation of PNECs from aquatic toxicity data?

• For derivation of PNECs from aquatic toxicity data, in Level 1, when should 1000 be used and when should 100 be used?

o 1000 is being conservative and should be used if 1 or 2 species are available.
o 100 can be used when all three groups are indicated and the data from chemicals suggest that the acute to chronic ratio will be less than 10 OR data suggests that the chemicals act via a non-specific or narcotic mode of action.

• For derivation of PNECs from aquatic toxicity data, in Level 2, when should 10 be used and when should 50 to 100 be used?

o 10 should be used if data on all 3 species is available
o 50-100 can be used if only 1 or 2 of the species are available.

• What is the PEC/PNEC ratio used for?

o It is used as an indicator of risk. It is called the risk quotient (RQ)

• What does RQ less than 1 mean?

o PEC is less than PNEC so no adverse effects are anticipated. The substance can be used.

• What does RQ equal to 1 mean?

o PEC is equal to PNEC. The two factors are very close indicating that adverse effects may occur.
o There are three possible actions for this: refine the assessment, reduce the usage, or don’t use it.

• What does RQ greater than 1 mean?

o PEC is greater than PNEC meaning adverse effects are likely to occur.
o This leads to 2 possible actions. Reduce usage until PEC is below PNEC, or don’t use it.