Jonathan M' Links, PhD Professor, Environmental Health Sciences Johns Hopkins Bloomberg School of Pu

1
Jonathan M. Links, PhDProfessor, Environmental
Health SciencesJohns Hopkins Bloomberg School of
Public HealthArea Leader Health the
Environment, JHINBT
Johns Hopkins Institute for NanobiotechnologyCel
lular molecular dynamicsDiagnostics
therapeuticsHealth the environment
2
Nanotechnology, Public Health, and the Environment

• The impact of nanotechnology (or nanomaterials,
  NM) on health and the environment is not known
  the focus of this presentation
• Nanotechnology has a role to play in solving
  problems in health and the environment an
  important thing to remember as we go along

3
Assessing and Managing NM Risks
Dose- response assessment
Hazard identification
Exposure assessment
Risk characterization
Risk Assessment NAS Red Book
Risk communication
Risk management
4
Hazard Identification

• Possible (and unique) toxicity issues with
  nanomaterials arise from
• The characteristics of engineered nanomaterials
  themselves
• The characteristics of products made from them
• Aspects of the life-cycle, starting with
  manufacturing processes

5
Do We Have Any Evidence of Toxic Effects?

• Extrapolation from quartz, asbestos, and
  particulate air pollution toxicology
• Some limited direct toxicological studies of
  nanoparticles
• Proposed new field Nanotoxicology (Occup Environ
  Med 61 727-728, 2004)
• By the way, the use of nanobiotechnologies for
  toxicology studies (Tox Sci 74 235-244, 2003)

6
Initial Tox Focus til Now

• Manufactured nanomaterials
• Carbon nanotubes
• Fullerenes
• Quantum dots
• Routes of exposure
• Inhalation
• Dermal absorption
• Biologic endpoints
• Oxidative stress
• Inflammatory response

7
Science 311 622, 2006
8
Exposure Assessment Whats in the Environment?
Half-life in env lt1/2 hr 1-2 weeks
lt1 hr
9
Exposure-to-Dose Assessment Whats in the Lungs?
10
Whats the Relevant Measure?
Relevant for Absorbed toxics
Rel for Env conc
Relevant for Adsorbed toxics
11
Why Study Health Environment Effects Now?

• Best chance to minimize risk
• Belatedly studying health and environmental risks
  halts technologies of widespread societal
  usefulness, leading to a scramble for functional
  substitutes
• e.g., chlorofluorocarbons (CFCs), asbestos
• Perceived risks slow development and use of
  beneficial technologies
• e.g., food irradiation, genetically modified
  organisms (GMOs)

12
Health and the EnvironmentFour Strategic
Research Foci

• Environmental transport, transformations, and
  fate
• Exposure assessment
• Toxicologic assessment
• Epidemiologic investigations

13
Environmental Transport, Transformations, and Fate

• From what sources and how are engineered
  nanomaterials introduced into the environment?
• Once introduced, where do such materials
  distribute (media and geography), and what
  physico-chemical transformations take place?
• How does the physical or chemical alteration of
  nanomaterials affect their transport, their
  chemical reactivity, and their toxicity?
• What are the fundamental structure-property
  relationships that govern transformations and
  ultimate fate in different ecosystems?

14
Exposure Assessment

• What basic physico-chemical characteristics
  (e.g., surface area, redox potential, adsorptive
  capacity) are most relevant to ecologic and human
  toxicity?
• How should we best characterize exposure, and
  what analytic methods need to be developed and
  validated to do so?
• For example, do we even have the current ability
  to reliably detect nanomaterials in the
  environment?

15
Toxicologic Assessment

• How should we best characterize dose and
  biologically effective dose?
• What adverse health outcomes should we measure
  (at the sub-cellular, cellular, organ system, and
  organism levels)?
• Can we develop practical toxicologic screening
  methods?
• What underlying biologic mechanisms drive
  nanomaterial-induced toxicity?
• Does synergism play a role? (It is likely that
  nanomaterials will adsorb other chemicals or
  biological agents, and these combinations could
  behave in novel ways.)

16
Epidemiologic Investigations

• What are the relevant patterns and pathways of
  human exposure to engineered nanomaterials?
• What are the most relevant adverse environmental
  and human health consequences?
• What prospective cohorts of potentially-exposed
  persons should be identified (prior to exposure)
  and monitored over time following exposure?