Chemistry Reference
In-Depth Information
public health triumphs of the late 20
th
century and
needs urgently to be extended to all nations.
4.
Current exposure standards for lead need urgently to be
reduced
. Current standards were established many
years ago and do not refl ect recent advances in sci-
entifi c knowledge about toxic effects at levels of
exposure below these standards. The Brescia Work-
shop recommends that:
●
●
All industrial uses, recycling processes, and
other industrial input of mercury into the envi-
ronment should be reviewed in all nations, and
non-essential uses should be eliminated and
releases controlled. This approach has been suc-
cessfully introduced in the EU and is actively
promoted by the United Nations Environmental
Program.
●
Mercury emissions from coal-fi red power plants
need to be curtailed.
●
All chlor alkali plants worldwide should be ur-
gently converted to alternative technologies that
are not based on mercury, and mercury stores
and wastes must be safely deposited.
●
Gold mining with mercury must be controlled
and enforced with safety guidelines, and alter-
native technology should be promoted.
●
Dietary advisories should be developed as ef-
fective, culturally appropriate means to limit
childbearing women's consumption of fi sh
contaminated with methylmercury. Taking
into account nutrient contents and availability,
healthy diets should be recommended with
fi sh and seafood containing minimal levels of
contamination.
6.
Exposures of pregnant women and young children to
manganese need to be reduced to prevent subclinical
neurotoxicity
. Important new data on the neurotox-
icity of manganese were presented at Brescia. In
adult workers, these data suggest that manganese
produces subclinical neurotoxicity at levels of ex-
posure below those that produce parkinsonism.
In children, evidence from two recent epidemio-
logical studies suggests that exposure to manga-
nese in early life causes subclinical developmental
neurotoxicity.
7.
The addition of organic manganese compounds to
gasoline should be halted immediately in all nations
.
The data presented at the Brescia Workshop raise
grave concerns about the likelihood that addition
of manganese to gasoline could cause widespread
developmental toxicity similar to that caused by the
worldwide addition of tetraalkyllead to gasoline.
In light of this information, it would be extremely
unwise to add manganese to gasoline.
8.
Exposure standards for manganese need to be reconsid-
ered
.The drinking water standards for manganese in
many countries are not based on health concerns, and
those that are do not protect against developmental
neurotoxicity resulting from exposures
in utero
and
in early postnatal life. The current occupational expo-
sure standard may not protect workers against sub-
clinical neurotoxicity. The value for air manganese
concentration in inhalable/total dust of 100
For children
, the action level, which triggers
community prevention efforts to reduce expo-
sure sources, should be immediately reduced to
a blood lead concentration of 50
g/L in nations
worldwide. This level is proposed as a tempo-
rary level that may need to be revised further
downward in future years as new evidence
accumulates on toxicity at still lower blood lead
levels. This reduction of the blood lead action
level will reduce the incidence of subclinical
neurotoxicity in children as well as the delayed
consequences of developmental toxicity.
µ
For industrial workers
, the standard for lead
in blood should be reduced immediately to
300
●
g/L in nations worldwide. Additional con-
sideration should be given to further reducing
this standard to 200
µ
g/L and below in the years
ahead. This reduction in exposure standard will
reduce the incidence of subclinical neurotoxicity
and other toxic effects during the working life
and responds to new documentation presented
at the Workshop that long-term lead exposure
increases the risk of dementia in later life.
µ
For female industrial workers of reproductive age
,
the standard for lead in blood should be re-
duced immediately in nations worldwide to the
lowest obtainable, preferably to 50
●
g/L, a level
consistent with the recommended blood lead
standard for children. Lead passes freely across
the placenta from the maternal to the fetal cir-
culation to enter the developing brain where it
causes prenatal brain injury. This recommended
reduction in maternal lead exposure will reduce
the incidence of fetal neurotoxicity in the off-
spring of women workers.
5. Exposures of pregnant women and women of repro-
ductive age to methylmercury need to be reduced
to prevent subclinical fetal neurotoxicity. Evidence
is strong that prenatal exposure to methylmercury
causes fetal neurotoxicity. Consumption of fi sh with
high mercury concentration by pregnant women is
the primary route of exposure. More than 50% of
the mercury in fi sh may be of industrial origin.
Strategies for reducing mercury exposure rec-
ommended by the Brescia Workshop are the
following:
µ
µ
g/m
3
