Nanomaterials and Definitions

- A Regulator’s Perspective

Dr Kerry Nugent

Principal Scientist

Existing Chemicals Program

NICNAS

The regulatory need

A strategy for the regulation of industrial

nanomaterials uses a tiered approach:

Tier 1: identify substances that should be captured

within this strategy

• “working definition”

– substances enter into the regulatory framework

Tier 2: risk assessment

– further definitional refinement

Distinguishing one chemical from another

• Chemical Identity

– eg name, CAS number

• Need for objective clarity in use of chemical

identity

– Each person using the identity information should

get the same answer

– Legal enforceability

Nanomaterial identity needs to account

for: • “Sameness”

– Need to identify when two nanomaterials have the

same chemical identity

• Existing Risk Assessment paradigms

– Nanomaterial definitions should not imply need for

nano-specific assessment when the material is

better dealt with by an existing methodology

– Need additional information

Sameness

• A generic risk assessment covers all materials that

are the same

• For nanomaterials, the boundaries of “sameness”

are not clear

• Potentially enormous number of variables

– Size, aspect ratio, surface morphology, surface

chemistry….

– Toxicological significance????

Existing Risk Assessment paradigms

• Many classes of chemicals that are currently risk

assessed meet nanoscale definition

– Globular proteins

– Colloidal polymers

– Large molecules

• Nano-specific assessment methodologies likely to

be less appropriate for these materials than

existing methodologies

– eg paint polymers – polymer of low concern

The NICNAS Working Definition

• … industrial materials intentionally produced,

manufactured or engineered to have unique

properties or specific composition at the

nanoscale, that is a size range typically between

1 nm and 100 nm, and is either a nano-object

(i.e. that is confined in one, two, or three

dimensions at the nanoscale) or is

nanostructured (i.e. having an internal or

surface structure at the nanoscale)”

Notes to the working definition

• intentionally produced, manufactured or engineered materials are

distinct from accidentally produced materials

• ‘unique properties’ refers to chemical and/or physical properties

that are different because of its nanoscale features as compared to

the same material without nanoscale features, and result in unique

phenomena (e.g. increased strength, chemical reactivity or

conductivity) that enable novel applications.

• aggregates and agglomerates are considered to be nanostructured

substances

• where a material includes 10% or more number of particles that

meet the above definition (size, unique properties, intentionally

produced) NICNAS will consider this to be a nanomaterial.

Considerations on the working definition

• Chemical identity

– Inherent in the definition

• Objectiveness

– “unique properties” is subjective

• Sameness

– Does not identify “sameness”

• Existing Risk Assessment paradigms

– Taken into account because of “unique properties”

ISO Definition Elements

• Nanoscale is objective and highly relevant

• Descriptive terms such as nanorod, nanoplate have

relevance for “sameness”

• Nanomaterial as any material with one or more

dimensions in nanoscale not a good regulatory

definition

– “bycatch” (existing paradigms)

– Does not address polydisperse materials