www.elsevier.com/locate/marpolbul

Marine Pollution Bulletin 50 (2005) 609–612

Editorial

Nanotechnology and the environment: Risks and rewards

If we look back over time at the history of scientific

innovation, some obvious breakthroughs stand out:

information technology and the advent of the computer

age, the discovery of DNA and the dawn of molecular

biology are but two examples. These scientific break-

throughs have changed society and the World we livein. Here in the first decade of the 21st century we now

stand on the brink of another watershed in scientific

innovation: nanotechnology. Many of us may be com-

pletely unaware that industry has embarked on a quite

extraordinary technological adventure, one which starts

with making a leap into the world of the very small—the

nanoworld. We may be largely unaware that the devel-

opment of nanotechnology is receiving huge investmentthat is global in scale and exponential in phase.

Nanotechnology is about producing structures, de-

vices and systems with one dimension between 1 and

100 nm. Just how small is this? A nanometer is one bil-

lionth (10�9) of a meter. You can gain some perspective

on this if you consider that a human hair is between

10,000 and 50,000 nm in diameter and that ten hydrogen

atoms in a line measure about 1 nm.To understand why nanotechnology it is set to be-

come such a significant part of the global economy in

the near future, we need to understand a little about

what happens to some substances, some of which we

may think of as being rather inert, when they become

very small. The properties of substances such as carbon

and titanium dioxide may change dramatically when re-

duced in size to the nanoscale. Below the 100 nm sizethreshold both the surface area to mass ratio and the

proportion of the total number of atoms at the surface

of a structure are large enough that surface properties

become important: this can alter chemical reactivity,

thermal and electrical conductivity and tensile strength.

Quantum effects begin to dominate, changing optical,

magnetic and electrical behaviour.

This size-related change in properties can make thesenanomaterials very attractive from a commercial point

of view. For example, development of single walled car-

0025-326X/$ - see front matter � 2005 Elsevier Ltd. All rights reserved.

doi:10.1016/j.marpolbul.2005.05.001

bon nanotubes for applications in the electronics, com-

puter and aerospace industries exploits their unique

electrical conductivity properties and the fact that they

are very lightweight, flexible but exhibit extremely high

tensile strength (Ball, 2001). The applications of nano-

technology are constrained only by imagination.Nanomaterials have applications in medicine (e.g. anti-

body-coated particles for targeted drug delivery), com-

mercial and industrial applications such as food

finishing, low friction lubricants, chemical catalysts,

nanoscale circuitry and nanosensors. And the products

of nanotechnology are not simply aspirational: they

are here today. Engineered nanoparticles alone are turn-

ing up in everything from well known brands of suncre-ams to widely-used fuel additives. Nanotechnology may

be about small things, but its becoming very big

business.

Nanotechnology could also confer large benefits to

the environment. Nanoscale circuitry could be more effi-

cient, offering enhanced electrical conductivity with re-

duced heat loss. In addition, innovative monitoring

and assessment nanotools (such as nanosensors) andremediation technologies are being developed (e.g. using

iron nanoparticles for remediating contaminated land

and groundwaters).

However, whilst altered physico chemical properties

make engineered nanomaterials commercially attractive

they also raise concerns regarding potential risks to

environmental and human health through consumer

use (e.g. cosmetics), occupational and environmentalexposure. Could these substances, some of which we

may currently think of as being quite benign, actually

be more toxic, more mobile, more persistent than their

bigger brothers? Could they be harmful to environment

and human health when manufactured in nanoform?

Are these nanomaterials slipping through the regulatory

net?

In fact, it is worth saying at the outset that exposureto nanoparticles is not a new phenomenon. Combustion

associated with natural and anthropogenic processes is a

610 Editorial / Marine Pollution Bulletin 50 (2005) 609–612

well known source of ultrafine material and the pulmon-

ary effects of ultrafine dusts (e.g. quartz) have been stud-

ied for many years (reviewed by Borm (2002)). What

these studies also tell us is that the fine (PM2.5) and

ultrafine (PM0.1) fractions are the most toxic compo-

nents of particulate matter. However, while nanoparticleexposure may not be a new phenomenon, it is the spec-

ialised manufacturing process associated with making

engineered nanoparticles and other nanomaterials,

where high surface area to mass ratios combine with

reactive surfaces, that make these potentially a special

case. Carbon nanotubes and carbon black for example,

are both carbon ultrafine material but may be quite dif-

ferent both in terms of their physico chemical behaviourand toxicity (Lam et al., 2004).

As with any technological breakthrough, there is a lot

at stake commercially. The past has taught us that real-

ising the potential benefits of nanotechnology to society

will require public confidence in its safety. Recognising

this, in July 2003 the UK Government commissioned

the Royal Society and Royal Academy of Engineers to

undertake an independent study summarising the cur-rent state of knowledge about nanotechnologies (e.g.

current and projected manufacture and products),

examine the health, safety and environmental risks and

ethical and societal implications associated with nano-

technology development and identify areas where regu-

lation should be considered. The report was published

in July 2004 and reviews much of the (in many instances

scant) information available to date on the issue (RoyalSociety and Royal Academy of Engineers, 2004).

The report focussed only on the potential health risks

from exposure to free engineered nanomaterials such as

nanoparticles and nanotubes. This raises an obvious but

important point: nanotechnology represents the devel-

opment of an incredibly diverse range of structures

and it is clear that a nanoparticle of titanium dioxide

and an instrument such as a nanotweezer are quite dif-ferent entities. By branding both as a single �nanotech-nology� one runs the risk of tarring all with the same

brush. Nanotechnology is very much a generic catch-

all term encompassing the development and commercial

exploitation of a range of structures: these include nano-

particles (e.g. of carbon (fullerenes or buckyballs), TiO2

and ZnO) and carbon nanotubes. These nanomaterials

are free, discrete structures. In fixed nanoproducts, thenanoscale active area forms part of a larger object, such

as a computer chip.

Some information was available to the Royal Soci-

ety�s working group to assess the potential human health

impact of free engineered nanomaterials: this drew on

studies of cellular toxicity and particle-induced lung dis-

eases associated with air pollution (ambient particu-

lates), mineral dusts, coal dusts, asbestos and a fewrecent studies on carbon nanotube pulmonary toxicity.

What is very noticeable is the almost complete absence

of scientific literature on environmental toxicity or expo-

sure to allow the undertaking of even the most basic

assessment of potential environmental and human

health risks associated with environmental exposure to

free, engineered nanomaterials. If the benefits of nano-

technology to society are to be realised it is clear thatthis issue needs to be comprehensively addressed.

The magnitude of the task associated with undertak-

ing environmental risk assessments, even for the range

of nanoparticles and nanotubes in current production

alone, should not be underestimated: firstly, almost

nothing is known about uptake, distribution and toxic-

ity in non-human species. One concern is the potential

unrestricted mobility of engineered nanomaterials suchas nanoparticles within organisms (Nemmar et al.,

2001). Indeed it is this translocatory potential that in

part makes nanoparticles commercially attractive for

drug delivery into poorly accessible compartments of

the body such as the brain.

There are almost no ecotoxicological (including mar-

ine) studies with engineered nanomaterials. One of the

only studies conducted with aquatic species (fish) sug-gests that oxidative stress may be a potential mechanism

of toxicity associated with free engineered nanoparticles

such as carbon C60 fullerenes (Oberdorster, 2004). Oxi-

dative stress and inflammatory reactions are known re-

sponses in the mammalian lung to ultrafine particulate

exposure from inhalation of, for example, coal dust. Re-

cent studies involving pulmonary exposure of carbon

nanotubes in rodents (Lam et al., 2004; Warheit et al.,2004) suggest that lung histopathological responses,

including inflammation and granuloma formation, may

also be significant. A more fuller understanding of basic

mechanisms of toxicity at a cellular level for nanomateri-

als will be important in the initial phases of general tox-

icological research. In total such studies can provide

provisional pointers as to further detailed areas for inves-

tigation in terrestrial, aquatic and marine species.The above toxicological studies with carbon nano-

tubes highlight an important point: carbon nanotubes

frequently contain residual catalytic metals (up to 27%

by weight, Lam et al., 2004), often dependent on the

method of manufacture. These studies show that the

type and residual metal content of the nanotube may

be important in terms of the relative toxicity. What this

means is that each type of nanoparticle and nanotubemay need to be assessed on a case by case basis, since,

while toxicological effects may possess similarities, the

exact nature and magnitude of that toxicity may be sub-

stance specific, and indeed may vary with size contin-

uum for that particular substance. In light of this,

there is a clear need to optimise or develop a range of

generic standard test procedures that can be applied to

a range of nanomaterials to assess their relative toxici-ties. This will require the reaching of a consensus on

appropriate endpoints that should be measured.

Editorial / Marine Pollution Bulletin 50 (2005) 609–612 611

Of course toxicity is only one part of the story: under-

standing exposure is equally important. But here again

there is virtually no information to allow even the most

basic assessment of nanoparticle or nanotube exposure

in the environment.

There may be direct inputs into the aquatic, marine,terrestrial ecosystems and atmosphere from initial and

downstream manufacturers (e.g. those who blend im-

ported, engineered nanoparticles). There may also be

non-industrial inputs e.g. consumer products including

sunscreens and cosmetics from both direct (e.g. bathing)

and indirect (sewer) sources, leaching from landfill or

soil-applied sewage sludge and atmospheric sources

from waste combustion. Central to this is the need toobtain regularly updated information on the nature

and magnitude of current and future sources of nano-

materials to the environment (a challenge since the

nanoscale industrial landscape is rapidly changing) and

understanding what happens to nanomaterials during

their journey from manufacture to waste disposal. This

can help to focus studies that can tell us about transport

pathways, biogeochemical cycling and environmentalfate. Ultimately such work will help us to identify which,

if any, environmental compartments are at risk of con-

tamination by nanomaterials.

Underlying this is the need to develop cost effective,

standardised methods for detecting and quantifying

the levels of nanomaterials such as engineered nanopar-

ticles in the environment and distinguishing these from

those that are naturally occurring. These will need tobe developed for a range of environmental media (from

air to marine waters to sewage sludge), critically

accounting for changes in behaviour within these media.

And this behaviour may not be simple: the physical

behaviour of nanoparticles and nanotubes tends to be

quite different when they enter water, where they can

readily clump together (Warheit et al., 2004) (although

development of surface treatments may serve to preventthis clumping behaviour). In the absence of such treat-

ment, formation of ultrafine colloids is likely to occur

and methods will need to be optimised or developed to

both measure these and to study how toxicity, persis-

tence and bioaccumulation changes in aqueous media.

Similarly, how nanomaterials influence the behaviour

and toxicity of existing chemicals present in the environ-

ment may be need to be addressed.Faced with so little information on toxicity and expo-

sure, environmental regulators are given little option but

to adopt a precautionary approach. Indeed, in some

countries such as the UK, this is what is happening.

The UK Government has recommended a voluntary

moratorium by industry on deliberate release of engi-

neered nanoparticles into the environment for remedia-

tion purposes and has asked industry to minimise releaseof engineered nanoparticles and nanotubes in waste

streams until the risks have been more comprehensively

assessed. The use of nanotechnology applications for

remediation (e.g. of contaminated groundwaters) is a

good example of an instance where there is urgent need

to obtain robust exposure and toxicity data; here is a

technology that can potentially remediate polluted

waters containing persistent chemicals, but in the ab-sence of a robust risk assessment responsible environ-

mental management dictates a precautionary approach

and delays the use of this potentially beneficial

technology.

In summary, the importance of nanotechnology for

sustaining economic growth has been recognised, but

it should also be recognised that safeguarding such

growth will depend on early public understanding ofboth the societal benefits offered by this technology as

well as health risks associated with its development

and use. Investing in risk assessment, management and

communication is the key to the responsible innovation

and the realisation of the potential rewards offered by

this new technology. Realisation of these benefits should

not be hindered by misplaced perceptions of risk to envi-

ronment and human health based on poor or no infor-mation. Conversely, it is clear that the development of

areas of nanotechnology, where the risks to human

and environmental health are shown to far outweigh

the benefits should be very carefully considered.

These are areas where academia, industry and regula-

tors will have to work closely together, on a co-ordi-

nated, international scale. The UK government is

beginning to co-ordinate such an approach in the UK,building on the recommendations within the Royal Soci-

ety and Royal Academy of Engineers report. This in-

cludes the formulating of a research agenda that builds

on some of the points highlighted above. In the US,

the EPA is funding a programme of environmental re-

search that includes investment in aspects of the risk

assessment process (http://es.epa.gov/ncer/nano/).

The time has come for the environmental researchcommunity to come together with the environmental

regulators to address this issue. Failure to undertake this

will almost certainly ensure that the media steers public

understanding of, and confidence in nanotechnology,

leading to unsubstantiated anecdotes and wild conjec-

ture potentially forming the basis for an ill-informed

debate with outcomes that may be wholly dispropor-

tionate to the risks.The views expressed in this article are not necessarily

those of the Environment Agency.

References

Ball, P., 2001. Roll up for the revolution. Nature 414, 142–144.

Borm, P.A., 2002. Particle toxicology: from coal mining to nanotech-

nology. Inhalation Toxicology 14, 311–324.

Lam, C.-W., James, J.T., McCluskey, R., Hunter, R.L., 2004.

Pulmonary toxicity of single-wall carbon nanotubules in mice 7

612 Editorial / Marine Pollution Bulletin 50 (2005) 609–612

and 90 days after intratracheal instillation. Toxicological Sciences

77, 126–134.

Nemmar, A., Vanbilloen, H., Hoylaerts, M.F., Hoet, P.H.M., Verb-

ruggen, A. et al., 2001. Passage of intratracheally instilled ultrafine

particles from the lung into the systemic circulation in hamster.

American Journal of Respiratory Critical Care Medicine 164,

1665–1668.

Oberdorster, E., 2004. Manufactured nanomaterials (fullerenes, C60)

induce oxidative stress in the brain of juvenile Largemouth Bass.

Environmental Health Perspectives 112 (10), 1058–1062.

Royal Society and Royal Academy of Engineers, 2004. Nanoscience

and nanotechnologies: opportunities and uncertainties. Available

from: <http://www.nanotec.org.uk/>.

Warheit, D.B., Laurence, B.R., Reed, K.L., Roach, D.H., Reynolds,

G.A.M., Webb, T.R., 2004. Comparative pulmonary toxicity

assessment of single-wall carbon nanotubes in rats. Toxicological

Sciences 77, 117–125.

Richard Owen

Michael Depledge

Science Group

UK Environment Agency

Burghill Road

Westbury-on-Trym, Bristol BS10 6BF

United Kingdom

E-mail address: richard.owen@environment-agency.

gov.uk (Richard Owen)