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Presentation Overview. Why the interest in NP/NPE?What are the Use and Disposal Patterns?What is the State of the Science on Exposure and Effects?What is the Relative Hazard of NPE and its degradation intermediates?What Can We Conclude about NP/NPE?. Why the Interest in NP/NPE?. Interest in NP/
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1. Environmental Safety of NP and NPE Dr. Ellen Mihaich
APERC Teleconference Series
June 20, 2003
2. Presentation Overview Why the interest in NP/NPE?
What are the Use and Disposal Patterns?
What is the State of the Science on Exposure and Effects?
What is the Relative Hazard of NPE and its degradation intermediates?
What Can We Conclude about NP/NPE?
3. Why the Interest in NP/NPE? Interest in NP/NPE biodegradability in the early 1980s
Connection of NP to the Endocrine Issue in the early 1990s
High volume, ubiquitous chemical
4. Chemical Structures
5. General Uses of NPE Industrial Processing (~50%)
Textiles, Pulp and Paper, Metal Processing, Emulsion Polymers and Coatings, Paints
Industrial, Institutional, and Household Cleaning (~50%)
Laundry Detergents, Hard Surface Cleaners, Agricultural Chemicals (inerts)
Personal Care (<1%)
6. Use and Disposal Patterns Application Disposal Practice Institutional and household cleaning products
Industrial processing aids
Paints and Coatings
Pesticide formulations Down the drain to treatment plant
On-site treatment or pre-treatment
Remain encapsulated
Sprayed onto foliage and soil
7. State of the ScienceExposure NP and NPE are biodegradable
NP/NPE are effectively removed (>95%) from effluent in well-functioning secondary sewage treatment plants
NP and NPE do not bioaccumulate and are not PBT compounds
Levels of NP/NPEs found in monitoring studies typically well below ppb level
However, environmental levels of concern can exist where treatment is inadequate
8. State of the ScienceEnvironmental Exposure USGS Study (2001)
Monitored for 95 substances in worst-case effluent-dominated streams
e.g., caffeine, cholesterol, estrogen, pharmaceuticals and various chemicals
Levels of NP/NPEs found were consistent with previous studies (Only 4 of 85 samples had NP > draft EPA Water Quality Criteria of 5.8 ppb)
9. Degradation Pathway Shortening of the EO chain proceeds via formation of carboxylated intermediates (NPEC)
Oxidation continues until EO chain shortened to NPE1,2
Enzymatic opening and mineralization of aromatic ring
NPE fully biodegrade to CO2 and H2O, even the aromatic ring portion
10. State of the ScienceEffects Numerous aquatic studies with NP/NPE/NP ether carboxylates (NPEC) with dozens of species
Endpoints include standard toxicity endpoints (survival, growth and reproductions) as well as subtle biochemical changes
Aquatic toxicity not endocrine issues drive risk assessment conclusions
11. What is the Relative Hazard of NPE and the Degradation Intermediates?
12. Data Review Process and Relative Hazard Assessment Critically reviewed chronic toxicity data
Chronic Values (ChV) calculated
ChV plotted according to EO chain length by endpoint
Species sensitivity distribution
Exposure compared to hazard for cumulative risk
13. Chronic Values for Fish (F), Invertebrates (INV) and Algae (ALG) by NPEx + Survival ChV
x Growth ChV
? Repro ChV
14. Species Sensitivity Distribution NP
15. Contribution of NPE, NPEC, NP to Total Hazard Quotient (HQ) in US Surface Waters
16. Conclusions NPEs are widely used and well studied surfactants
They are present in many industrial and down-the-drain applications
Considerable aquatic toxicity data exists for the parent as well as the degradation intermediates
Risk Assessment conclusions are not driven by endocrine activity
17. Conclusions Typical concentrations of NP/NPEs in the environment are very low
NP is a minor degradation intermediate
Cumulative exposure assessment compared to hazard shows concentrations in the surface water do not exceed a safe level
The draft EPA Water Quality Criteria (~ 5.8 ppb) is supported by this assessment