Environmental Engineering Reference
In-Depth Information
Serious illness and death have been attributed to the use of earthenware pottery
with improperly heated lead-based glaze. Such glaze dissolves in fruit juice, acid
salad dressing, tomato sauce, coffee, wine, soda pop, and other soft acid drinks.
Most of the glaze applied to pottery contains lead. When pottery, dinnerware, and
other ceramics are not fired long enough at the correct temperature or the glaze
is not properly formulated, the glaze will not fuse and seal completely and its
lead (and possibly cadmium) component can be leached or released. Moonshine
whiskey made in stills containing lead has also been implicated. The FDA has set
a limit of 0.5 ppm lead leachate for ceramics used to store acid liquids (including
large bowls) and 7.0 ppm for ceramics used for liquids or food service (dishes),
with 5.0 ppm for small bowls. Commercial laboratories can analyze dishes, bowls,
pitchers, and cups for improper lead glaze.
Control of lead poisoning is approached through identification and removal
of lead sources and through screening of children, workers and their families
where exposure has occurred. This includes residents of neighborhoods with
older homes that have not been kept up.
Additional controls include identification through selective systematic inspec-
tion of housing, mostly built before 1950 or 1960, and removal of lead-based
paint containing more than 0.05 percent lead by weight; prohibition of sale of
toys or baby furniture containing lead paint; removal of dust from floors by wet
mop or vacuum; and promotion of hygiene and handwashing by children and
adults; education of parents, social workers, public health professionals, health
guides, owners of old buildings, and those occupationally exposed to the hazard
and its control. The X-ray fluorescence lead paint analyzer has improved hazard
identification. Paint analysis by a laboratory is necessary for lead concentrations
below the fluorescence analyzer sensitivity. Building codes should prohibit the
use of lead solder, pipe, and fittings. The sale of drinking water coolers with
lead-lined tanks or piping is also prohibited. Lead water service lines should be
replaced.
The national ambient air quality standard for airborne lead is 1.5
µ
g/m
3
of
air averaged over a 3-month period. The OSHA permissible lead exposure level
averaged over an 8-hour work day is 50
µ
g/m
3
, but if the air-borne lead concen-
tration averages 30
µ
g/m
3
during a work shift, a control program and medical
surveillance are required. Persons who work in lead smelters, brass foundries,
storage battery - manufacturing plants, and plastic-compounding factories and per-
sons cutting through metal structures coated with lead-based paint or who remove
such paints from tanks or other structures are at high risk for lead toxicity.
It is believed that lead poisoning contributed to the decline of the Roman
Empire and the associated deaths, disease, and sterility. The poisoning was due
to water distribution in lead pipes and the widespread practice of cooking in
lead-based utensils (old pewter), particularly the cooking of a syrup used to
preserve and enhance the taste of wine.
There is evidence that there is no acceptable level of lead in humans. Even
low levels (below 25
µ
g/dl) may cause brain damage. It is theorized “that lead,
