Environmental Safety of NP and NPE

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Environmental Safety of NP and NPE

• Dr. Ellen Mihaich
• APERC Teleconference Series
• June 20, 2003

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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?

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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

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Chemical Structures
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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 (lt1)

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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

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State of the ScienceExposure

• NP and NPE are biodegradable
• NP/NPE are effectively removed (gt95) 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

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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 gt
  draft EPA Water Quality Criteria of 5.8 ppb)

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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

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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

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What is the Relative Hazard of NPE and the
Degradation Intermediates?
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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

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Chronic Values for Fish (F), Invertebrates (INV)
and Algae (ALG) by NPEx

• Survival ChV
• x Growth ChV
• ? Repro ChV

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Species Sensitivity Distribution NP
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• Contribution of NPE, NPEC, NP to Total Hazard
  Quotient (HQ) in US Surface Waters

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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

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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