Chemistry Reference
In-Depth Information
3.2.6 Housekeeping
is also important from the point of view of reducing
exposure to the worker's family (Baker
et al.,
1977a).
Smoking is another hazard in the industrial environ-
ment. Large amounts of metallic dust may accumu-
late on smoke particles from cigarettes, cigars, and
pipes and be transferred to the human body (of the
smokers and nonsmokers alike) through respiration
or by direct contact with contaminated hands on
sandwiches and other foods. Aerosolized metals may
also be inhaled through burning tobacco products,
causing even more hazardous products of combus-
tion—all the more reason for prohibiting smoking in
the workplace.
Poor housekeeping can render even the best
technical control system ineffective. Education and
supervision should be detailed and protective meas-
ures enforced. Clothing made of synthetic fi bers retains
less dust than cotton overalls. Pockets should be as few
as possible, especially when metallic mercury is present
in the workroom. Working clothes should be vacuumed
before removal and changed at least twice a week. Metal
workers need to be provided with changing and shower-
ing facilities, and work and street clothes should be stored
in separate lockers to reduce the exposure to the worker
himself and to prevent the worker from exposing his fam-
ily (Baker
et al.,
1977a).
Because most metals occur in dust form or precipi-
tate as small particles in fumes, exposure can be reduced
by keeping the workplace fl oor permanently mois-
tened and by frequent vacuum cleaning. Dry sweeping
should be avoided, because this will re-entrain settled
dust into the workroom air. The use of compressed air
to blow dust from fl oors, walls, and ledges should be
prohibited. In principle, all cleaning and other opera-
tions that may cause settled dust to whirl about should
be performed outside of normal working hours by
specially trained, well-protected workers.
When moistening the fl oor, the water should never
come in contact with molten metal, because violent
explosions can occur. Operations involving the weld-
ing, fl ame-cutting, or burning of metals coated with
paint of unknown composition should not be allowed
before samples have been analyzed at least for lead,
cadmium compounds, and chromates, or until the com-
position has otherwise been explained. If such metal-
based pigments are present, the burning is extremely
dangerous and should be performed under powerful
local exhaust ventilation and, if possible, outside the
normal working hours. Metals coated with metallic
cadmium should be treated in the same way. Even less
toxic metals, such as zinc, found in galvanized metals
and brass can cause metal-fume fever, and welding and
burning these demand the same protective measures.
3.2.8 Reduction of Worker Contact with Toxic Metals
and Personal Protective Equipment
When metal toxicity occurs, the ideal solution is
immediate cessation in use of the toxic metal. Typi-
cally, such drastic action requires a legally mandated
ban enforced by governmental authorities, although it
may also be achieved by voluntary agreement. A sec-
ond, less optimal approach is to remove the worker
from exposure whenever the concentrations of the
metal in the blood or urine exceed the action level,
when early symptoms or signs are present, or when
reports of exceptional exposure peaks are made. Ide-
ally, the worker should be transferred to a job that is
free from exposure. Otherwise, compensated sick leave
may be considered, as well as job transfer at the same
level of compensation. For lead workers in the United
States, the latter approach is legally required under
the Medical Removal Protection program established
through the OSHA Lead Standard (OSHA, 2005). The
worker should not be allowed to return to exposure
until his or her blood lead levels are well below the
recommended upper limits.
Workers should spend as little time as possible in
areas with unusually high concentrations of metal dust
or fumes. These areas include the vicinities of smelt-
ing furnaces, welding places, and pasting machines
in storage battery factories. When engaged in weld-
ing or burning outdoors, the worker should be trained
to always place himself upwind, and other workers
should not be asked to work downwind from the weld-
ing or burning operation.
If large-scale engineering methods such as automa-
tion and encapsulation fail to ensure adequate safety,
personal protective equipment may be used, but only
as a last resort. The only situations in which respirators
and other forms of personal protective equipment can
be considered a primary choice for worker protection
are during emergencies and occasional, brief expo-
sures, such as in repair and maintenance operations.
3.2.7 Infl uence of Personal Hygiene on Metal
Absorption and Toxicity
Both the industrial and the general environment
present many possibilities for contamination of
hands and clothing with metal compounds. Because
of the danger of food becoming contaminated from
the environment or from dusty hands or clothes, food
should never be prepared, dispensed, or eaten in areas
where there is metal dust. Dining rooms should be
clean. Personal hygiene should be facilitated by pro-
viding suffi cient washrooms. Good personal hygiene
