crystal glass is a quality European export but the very fact that it contains
lead means workers may be at risk from metal-laden fumes and makes waste
disposal difficult. Multidisciplinary teams worked successfully together
in a CRAFT project to show that proposed alternatives have low potential
toxicity and can be disposed of safely in ordinary landfill sites. The
alternative metals were used to make glass crystal that even experienced
experts find difficult to tell apart from lead crystal. There is now pressure
from some sectors of the industry to redefine crystal glass, thus allowing
safe and environmentally friendly crystal to be made using these alternative
definition of lead crystal as glass that contains a minimum of 24% lead
oxide is a feature that once contributed to its reputation for quality.
Today, however, it is causing consumer disquiet. Denmark wants to ban
all imports containing lead, while some states in the USA require lead
crystal glass to carry a health warning.
consumer's point of view, there is minimal risk as virtually no lead leaches
from glass during normal use. However, lead is an extremely toxic metal
that is retained for a long time in the body. For glass workers, exposure
to high levels of lead is a potential occupational hazard and the toxicity
of glass waste also poses long-term problems for waste disposal.
safe alternative to lead?
is a thorny issue," says Professor Nick Priest of Middlesex
University in London. "Other metals can be used in glass-making
to impart the same physical properties, but we had no safety information
for any of them."
companies that control the international markets and that have their
own research and development departments dominate the glass industry.
European SMEs find it difficult to compete in the best of circumstances
but, a couple of years ago, with building pressure from Denmark
and the USA, they decided to take the initiative. In late 1997,
SMEs from Ireland, Norway, Portugal, Sweden and the UK formed a
research partnership under a BRITE-EURAM
project to assess the safety of lead substitutes within crystal
glass. To help, they recruited research organisations in Ireland,
Sweden and the UK.
project set out to answer questions in three main areas.
1. Consumer safety: could alternative metals be
used to make glass that was safe for ordinary people to use? Would
the metals in crystal glass containers leach out into liquids
such as orange juice and wine making the containers unsafe to
2. Worker safety: how are workers exposed to toxic
metals during crystal glass manufacture? Does the manufacture
of crystal glass containing metals such as bismuth, barium and
strontium present a hazard to workers in the crystal industry?
3. Environmental impact: did the alternatives present
any environmental problems in disposal or recycling?
collaboration between the numerous partners occurred at many levels
and was very complex. Analytical tasks were shared between the different
RTD suppliers. Companies assisted by setting up manufacturing runs
specifically for the project, to produce test beakers of standard
size. Firms also allowed their current manufacturing processes to
be fully monitored and they contributed specially produced waste
for disposal studies.
of the tasks were carried out by several partners jointly, so that
fully multidisciplinary teams could work together. The planning
and logistics of the various sub-projects was not easy but everything
went very smoothly," confirms Professor Priest. "Without
this sort of co-operation, it would have been difficult for any
single SME to have obtained the information that came out of the
project in just 24 months. This is helping SMEs involved to compete
on a more equal footing with the few giant glass manufacturers within
pose no safety risks
results showed that none of the metals tested - bismuth, barium,
strontium, zinc and titanium - pose any risk to safety during the
manufacturing, waste disposal or product usage stages. Products
made from glass containing these metals are virtually indistinguishable
from the highest quality lead crystal and the manufacturing process
is unhampered - although it is yet to be confirmed that crystal
glass can be cut and polished in the same way as traditional lead
key finding from the factory studies is that most metal exposure
occurs at the hot blowing stage in the process," observes Professor
Priest. The fumes produced by heated glass are absorbed easily through
the lungs, whereas the fine mist of glass fragments produced during
cutting is relatively harmless. In the tests, most of the other
metals proved not to be volatile when heated, so they present a
low inhalation risk. Bismuth is volatile and is toxic, but human
volunteer studies, using the radioactive isotope 207Bi, showed that,
unlike lead, bismuth is not retained in the body.
new era in glass making?
the end of the project, the CRAFT study had failed to find any evidence
to suggest that the alternative metals could not be used in safe
and effective glass manufacture. Moreover, the crystal glasses did
not leach under landfill conditions, had a high potential for recycling
within the art glass and ceramic glaze industries and could even
be legally recycled within container glass streams. The study generated
sufficient data for the creation of safety cases for a wide variety
of different possible and likely crystal glass compositions.
that we have the data to go forward, we have made this available
to the whole of the glass industry. It is difficult to predict what
will happen in the near future, but there seems a good chance that
this project will enable SMEs that manufacture uncut glass to take
the initiative to switch over to alternative methods of producing
crystal glass. Further research may allow manufacturers of cut products
to make a similar switch," explains Nick Priest. This could
give them a significant advantage in new and developing international
would seem that the SMEs can look forward to breaking into new markets
as producers of safe, environmentally friendly glass.