Chemistry Reference
In-Depth Information
●
Removal of mercury-containing thermometers
from hospitals and their replacement by elec-
tronic devices.
●
The use of copper- or nylon-clad bullets with
nonlead primers at indoor fi ring ranges, instead
of lead-containing bullets.
●
The use of composite materials and ceramics
instead of mercury amalgam for dental fi llings.
●
The introduction of cement with negligible
chromate content.
fl oor. Secondary lead smelting is such a hazardous
process that priority should be given to automation
of transportation and oven-fi lling phases. The prepa-
ration of all metal pigments, very hazardous when
done by hand, becomes far less dangerous in closed,
automated systems. Instead of dust-producing pow-
ders, liquid premixes are preferred.
For more detailed information about these
approaches, the reader is referred to basic textbooks
in industrial hygiene, such as DiNardi (1998), Harris
(2000), LaDou (2004), Levy
et al
. (2000), and Plog
et al
.
(1996). In addition, Volume III of the
ILO Encyclopedia
of Occupational Health and Safety
is particularly useful
for metals use and control measures in various mining
and metalworking industries (Stellman, 1998).
3.2.2 Reduced Use of Toxic Metals in Plant and
Manufacturing Design
It is axiomatic that a properly designed new facility
that incorporates state-of-the-art control measures will
be safer, more effi cient, and more economical than an
older facility, where ventilation and safety equipment
must be retrofi tted. Success is usually greatest when
technical and medical knowledge can be applied in the
planning stages of a new facility to eliminate or limit
the use of toxic materials as much as possible. The focus
of toxic use reduction is to eliminate or control use of
toxic materials in manufacturing at the plant design
stage, rather than cleaning up the environment after
its use. In 1989, the Commonwealth of Massachusetts
(United States) passed a landmark Toxic Use Reduction
Act (TURA) (General Laws of Massachusetts, Ch. 21
I @
www.mass.gov
). Techniques favored under this Act
include substitution, product reformulation, redesign
of production processes, improved housekeeping, and
further recycling and reuse of waste products. For
more information on toxics use reduction see Geiser
and Commoner (2001).
3.2.4 Local Exhaust Ventilation
One of the best means for controlling dust or fumes
in the workplace is a local exhaust system, in which
intake is as close as possible to the point of origin of the
dust or fume. The system for removal of the polluted
air must be constructed, so as not to draw the contami-
nated air into the breathing zone of the worker on its
way to the exhaust. The air taken into this system must
be fi ltered and the metals removed, so that the gen-
eral environment outside of the factory will not be pol-
luted. All air fi lters should be inspected frequently and
changed on a regular schedule. Self-made “improve-
ments,” such as ductwork extensions, may be deleteri-
ous to the effi cient functioning of the system and may
cause deterioration of system equipment. For further
details see Burton (1998; 2005), George and DiNardi
(1998), and Soule (2000a).
3.2.3 Other Technical Control Measures
3.2.5 General Room Ventilation
The technical control of metal exposures in the
workplace follows the principles of industrial
hygiene. Forms of automation can be used to reduce
workers' contact with hazardous processes. When-
ever possible, all hazardous types of exposure should
be concentrated in specially enclosed areas where
control processes can be effectively used. Encapsula-
tion and other isolation methods prevent toxic dusts
and fumes from being spread about, and special well-
ventilated control rooms can be built within the plant
to enclose the most dangerous processes. Surfaces
should be smooth to prevent dust from attaching to
walls and fl oors. Nooks and corners, where dusts can
accumulate, should be avoided. For example, in the
case of metallic mercury, the worst problem is evapo-
ration from spilled droplets. Their removal is facili-
tated by smooth, nonabsorbing surfaces that round
up in the corners and slant toward the center of the
Good general room ventilation is important to the
quality of working life within a facility, but it is not a
particularly effi cient adjuvant to a local exhaust sys-
tem—indeed, an improperly designed room ventila-
tion system can undermine the effi cient operation of
a local exhaust ventilation system. Because general
systems involve much higher costs, for example, in
energy consumption, the emphasis should be put on
local controls. It should be stressed that open win-
dows and doors, as well as changes in the working
process, may thwart otherwise effi cient room and
local exhaust ventilation systems. Proper caution
and careful maintenance are especially important
when recirculated air is used for workroom ventilation,
as in heating, ventilation and air-conditioning (HVAC)
systems. For further details see AIHA/ANSI Z9
Committee (2004), Burton (1996; 1998), and Harris
and Arp (2000).
