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Transcript of March, 2014 Jennifer Sass, NRDC Lauren Heine, Clean ... · PDF fileJennifer Sass, NRDC ....

  • "Utility of the Greenscreen for Safer Chemicals for nanoscale hazard assessment:

    nanosilver case study"

    March, 2014

    Jennifer Sass, NRDC Lauren Heine, Clean Production Action

    http://www.nrdc.org/

  • Goal: Moving to Safer Ingredients and Driving Transparency

    In the absence of mandatory product labeling, public debate or laws to ensure their safety, products created using nanotechnology have entered industries, workplaces, and consumer markets. "We currently know very little about nanoscale materials' effect on human health and the environment. The same properties that make nanomaterials so potentially beneficial in drug delivery and product development are some of the same reasons we need to be cautious about their presence in the environment"

    Linda Birnbaum, Ph.D., director of NIEHS and the NTP

  • Can We Use the GreenScreen (GS) to Assess Nanomaterials?

    Goal - Test the GS as a vehicle to gather and communicate hazard information on nanomaterials Approach - Convene a prominent group of independent scientific experts to: Define scope of nanomaterials and studies to assess; (size distribution, shape, structure charge, coating, surface chemistry, agglomeration/aggregation, etc); Recommend relevant modifications to the GS method. Apply the GS to selected nanomaterials (use independent contractor, NSF) Review results with scientific experts and NGOs

    PresenterPresentation Notes

  • What is the GreenScreen? A method for comparative Chemical Hazard Assessment (CHA)

    developed by the NGO Clean Production Action Allows you to compare chemicals based on hazard in a

    comprehensive and consistent framework a level playing field Builds on the USEPA DfE approach and other national and

    international precedents (OECD, GHS) Free and publicly accessible, transparent and peer reviewed Considers 18 environmental and human health endpoints Addresses constituents and breakdown products Evaluates hazards for an overall chemical score (Benchmark)

    All supporting resources at: http://www.cleanproduction.org/Greenscreen.v1-2.php

    4

    PresenterPresentation NotesGS assesses chemicals according to eighteen hazard endpoints (including chronic and acute toxicity, ecotox, and physical characteristics such as flammability and reactivity), scores each endpoint according to the available data or identifies a data gap, and then uses this information to assign a Benchmark score (BM) from 1 to 4, with 1 being the most hazardous.

  • GreenScreen Adoption

    Corporate materials selection (HP) Corporate policies (Staples) State regulations (ME, WA) Ecolabels and standards (USGBC LEED v4) Alternatives assessments

    PresenterPresentation NotesGS builds on the US EPA Design for the Environment (DfE) approach, along with global OECD Globally Harmonized System (GHS) and other accepted systems. The use of comparative chemical hazard assessments can support informed decision making by regulators, policymakers, product designers and chemists.

  • 18 Hazard Endpoints Human Health

    Group I Human Health Group II

    and II* Environmental Toxicity & Fate

    Physical Hazards

    Carcinogenicity

    Acute Toxicity

    Acute Aquatic Toxicity

    Reactivity

    Mutagenicity & Genotoxicity

    Systemic Toxicity & Organ Effects

    Chronic Aquatic Toxicity

    Flammability

    Reproductive Toxicity

    Neurotoxicity Other Ecotoxicity studies when

    available

    Developmental Toxicity

    Skin Sensitization Persistence Respiratory Sensitization

    Endocrine Activity Skin Irritation Bioaccumulation

    Eye Irritation

    6

    Assign a level of concern for each hazard endpoint e.g. carcinogenicity (H, M or L)

  • Make Informed Decisions Know what you know, and what you dont know Benchmarks provide a simple 1-4 score that supports taking action

    BM1 avoid/phase out BM2 manage, to use safely BM3 getting there BM4 inherently low hazard

    Can be used by non experts in toxicology to support product design, policies and regulations 7

    PresenterPresentation NotesGS assigns a Benchmark score (BM) from 1 to 4, with 1 being the most hazardous. Where there are no data for an endpoint, GS can use analogs, modeled data, or other available reasonable substitutes to inform that endpoint. Confidence in the score is identified as high (a bold letter), low (an italics), or very poor (DG, data gap). Chemicals that are carcinogens, mutagens, reproductive and developmental toxicants, endocrine disruptors, and PBTs (persistent, bioaccumulative, and toxic) would be considered substances of high concern, with a BM 1.

  • Nano Silver

    Applications for nanosilver: Coatings: for food packaging, food cutting boards, clothing, films,

    fabrics Medical: wound dressing, dental hygiene, and treatment of eye

    conditions and other infections Water treatment processes: surface coatings, including washing

    machines and paints leads to significant silver discharge

    PresenterPresentation NotesMaterials 2013, 6, 2295-2350; doi:10.3390/ma6062295 Mechanisms of Silver Nanoparticle Release, Transformation and Toxicity: A Critical Review of Current Knowledge and Recommendations for Future Studies and Applications Bogumia Reidy 1,*, Andrea Haase 2, Andreas Luch 2, Kenneth A. Dawson 1 and Iseult Lynch 1,3

  • The specific materials evaluated for this case study were nanoscale metallic silver, a nano silica-silver nanocomposite, and conventional silver (dispersed low-solubility dispersed silver and silver salts). The extent of nanoscale test material characterization was considered in assessing the adequacy of the studies used.

  • 10

    GreenScreen DRAFT Results - nanosilver Route GreenScreenHazard Ratings: Dispersed (low-solubility, non-nanoscale) silver - Benchmark Score of 1 based on combined very High

    Persistence coupled with very High Ecotoxicity, as determined in standardized tests.

    Group I Human Group II and II Human Ecotox Fate Physical

    C M R D E AT ST N

    SnS SnR IrS IrE AA CA P B RX F Single Repeated

    Single Repeated

    Oral DG

    L

    DG DG

    DG

    L DG DG DG DG

    L DG L L vH vH vH L L L Dermal DG DG DG L DG DG DG DG Inhalation DG DG DG DG DG DG DG DG

    Route GreenScreenHazard Ratings: Nanosilver, metallic - Benchmark Score of 1 based on very High Persistence coupled with High systemic toxicity and very High Ecotoxicity.

    Group I Human Group II and II Human Ecotox Fate Physical

    C M R D E AT ST N

    SnS SnR IrS IrE AA CA P B RX F Single Repeated

    Single Repeated

    Oral DG

    L

    DG DG

    DG

    L DG M DG DG

    L DG L L vH vH vH L DG DG Dermal DG DG DG L DG DG DG DG Inhalation DG DG DG vH DG H DG DG

    Route GreenScreenHazard Ratings: AGS-20 (silver-silica nanocomposite containing 19.3% silver nanoparticles imbedded in a matrix of amorphous silicon dioxide) - Benchmark Score of U (unspecified) based on numerous datagaps.

    Group I Human Group II and II Human Ecotox Fate Physical

    C M R D E AT ST N

    SnS SnR IrS IrE AA CA P B RX F Single Repeated

    Single Repeated

    Oral DG

    DG

    DG DG

    DG

    L DG DG DG DG

    L DG L M DG DG vH DG L L Dermal DG DG DG L DG DG DG DG Inhalation DG DG DG M DG DG DG DG

    PresenterPresentation NotesBoth silver and nanoscale silver were classified as BM1 (highest concern), based primarily on high aquatic toxicity, persistence, and acute inhalation toxicity for nanosilver (for conventional silver, there were no data on this endpoint). The silica-nanosilver composite, a form recently conditionally approved by EPA for use in textiles as an antimicrobial agent, was unassigned (BM Unspecified (U)) due to data gaps. The form of these materials mattered more than size for acute inhalation hazard, where nanosilver was much more hazardous than the silica-nanosilver composite, likely because there is more silver in the nanosilver than in the composite.

    For eye irritation hazard the form also influenced the outcome, with the reverse result that the silica-nanosilver composite was more hazardous than both the nanosilver and conventional silver, with the latter two being about equal. In this case, the larger size of the composite (micron scale) may be driving its irritation hazard.

    For aquatic toxicity, size matters in that particle aggregation reduced the hazard, likely by reducing surface area and thereby reducing reactivity of the silver. This suggests that high aquatic hazards may be mitigated if the bioavailability of the material is reduced in natural waters, for example by agglomeration or by product design to reduce the release of silver ion from products such as textile products.

    The EPA approval of AGS-20 was based in part on the assumption that toxicity is governed by Ag+ ions, thus silver nitrate could be used as an analog to fill data gaps. This GS did not use silver nitrate as an analog to fill datagaps, because the point of the screen was to examine particle size-specific hazards. There are scientific justifications for both positions.

    Note: Exposure routes include Oral (o), Dermal (d), and Inhalation (i). Hazard levels are Very High (vH), High (H), Moderate (M), Low (L), and Very Low (vL)). Italics reflects estimated values and lower confidence, as with data gaps (DG), whereas BOLD font reflects values based on test data (see guidance). Endpoints include Carcinogenicity (C), Mutagenicity / Genotoxicity (M), Reproductive Toxicity (R), Developmental and/or Neurodevelopmental Toxicity (D), Endocrine Activity (E), Acute Mammalian Toxicity (AT), Systemic Toxicity Single