IPCS INTERNATIONAL PROGRAMME ON CHEMICAL SAFETY
Health and Safety Guide No. 70
INORGANIC ARSENIC COMPOUNDS
OTHER THAN ARSINE
HEALTH AND SAFETY GUIDE
UNITED NATIONS INTERNATIONAL
ENVIRONMENT PROGRAMME LABOUR ORGANISATION
WORLD HEALTH ORGANIZATION
WORLD HEALTH ORGANIZATION, GENEVA 1992
Published by the World Health Organization for the International
Programme on Chemical Safety (a collaborative programme of the United
Nations Environment Programme, the International Labour Organisation,
and the World Health Organization)
This report contains the collective views of an international group of
experts and does not necessarily represent the decisions or the stated
policy of the United Nations Environment Programme, the International
Labour Organisation, or the World Health Organization
WHO Library Cataloguing in Publication Data
Inorganic arsenic compounds other than arsine: health and safety
guide.
(Health and safety guide ; no. 70)
1.Arsenic - standards 2. Arsenic - toxicity
3. Environmental exposure I.Series
ISBN 92 4 151070 6 (NLM Classification: QV 294)
ISSN 0259-7268
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(c) World Health Organization 1992
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CONTENTS
INTRODUCTION
1. PRODUCT IDENTITY AND USES
1.1. Identity
1.2. Physical and chemical properties
1.3. Analysis
1.4. Composition
1.5. Production and uses
2. SUMMARY AND EVALUATION
2.1. Natural occurrence and biological transformations in the
environment
2.2. Human exposure
2.3. Effects on organisms in the environment
2.4. Uptake, metabolism, and excretion
2.5. Effects on experimental animals
2.6. Effects on humans
3. CONCLUSIONS AND RECOMMENDATIONS
3.1. Conclusions
3.2. Recommendations
4. HUMAN HEALTH HAZARDS, PREVENTION AND PROTECTION, EMERGENCY ACTION
4.1. Human health hazards, prevention and protection, first aid
4.1.1. General population
4.1.2. Occupationally exposed population
4.1.3. First aid
4.2. Advice to physicians
4.2.1. Treatment
4.3. Explosion and fire hazards
4.4. Storage and transport
4.5. Spillage
4.6. Disposal
5. HAZARDS FOR THE ENVIRONMENT AND THEIR PREVENTION
6. CURRENT REGULATIONS, GUIDELINES, AND STANDARDS
6.1. Previous evaluations by international bodies
6.2. Exposure limit values
6.3. Specific restrictions
6.4. Transport and labelling
BIBLIOGRAPHY
INTRODUCTION
This Health and Safety Guide is not based on an existing Environmental
Health Criteria document, but on critical national reviews. The
hazard evaluation in the Health and Safety Guide was made on the basis
of carefully selected studies, after scrutiny of the original
publications.
In order to assist the peer-review process of the present Health and
Safety Guide, a background companion document was prepared by the IPCS
and can be obtained from the Director on request; the IPCS does not
intend that the background document should be published.
The first three sections of this Health and Safety Guide present
essential technical information and the hazard evaluation. Section 4
includes advice on preventive and protective measures and emergency
action; health workers should be thoroughly familiar with the medical
information to ensure that they can act efficiently in an emergency.
The section on regulatory information has been extracted from the
legal file of the International Register of Potentially Toxic
Chemicals (IRPTC) and from other United Nations sources.
The target readership includes occupational health services, those in
ministries, governmental agencies, industry, and trade unions who are
involved in the safe use of chemicals and the avoidance of
environmental health hazards, and those wanting more information on
this topic. An attempt has been made to use only terms that will be
familiar to the intended user. However, sections 1 and 2 inevitably
contain some technical terms.
Revision of the information in this Guide will take place in due
course, and the eventual aim is to use standardized terminology.
Comments on any difficulties encountered in using the Guide would be
very helpful and should be addressed to:
The Director
International Programme on Chemical Safety
World Health Organization
1211 Geneva 27
Switzerland
THE INFORMATION IN THIS GUIDE SHOULD BE CONSIDERED AS A STARTING POINT
TO A COMPREHENSIVE HEALTH AND SAFETY PROGRAMME
1. PRODUCT IDENTITY AND USES
1.1 Identity
The chemical names, synonyms, trade names, chemical formulae and CAS
numbers of some inorganic arsenic compounds are given in Table 1.
Table 1. Chemical names, synonyms, trade names, and chemical formulae of some inorganic
arsenic compounds
Chemical name Formula CAS-No. Synonyms and trade names
Arsenic As 7440-38-2 Arsen; arsenic black; grey
arsenic; metallic arsenic
Arsenic pentoxide1 As205 1303-28-2 Arsenic acid; arsenic acid
anhydride; arsenic [V] oxide;
diarsenic pentoxide; arsenic oxide
Arsenicsulfide As2S3 1303-33-9 Arsenic sesquisulfide;
arsenic sulfide; arsenic
tersulphide; arsenic trisulphide;
arsenic yellow; arsenious
sulphide; arsenous sulphide;
auripigment; C.I. 77086;
C.I. pigment yellow; diarsenic
trisulphide; orpiment; King's Gold
Arsenic AsCl3 7784-34-1 Arsenious chloride; arsenic
trichloride butter; arsenous
chloride; caustic arsenic
chloride; caustic oil of arsenic;
fuming liquid arsenic
Arsenic trioxide2 As203 1327-53-3 Arsenic[III]oxide; arsenic
sesquioxide; arsenicum album;
arsenious acid; arsenious oxide;
arsenious trioxide; arsenite;
arsenous acid; arsenous anhydride;
arsenous oxide; arsenous oxide
anhydride; crude arsenic;
diarsenic trioxide; arsenic oxide;
white arsenic; Arsenolite;
Arsodent; Claudelite
Chemical name Formula CAS-No. Synonyms and trade names
Calcium arsenate Ca3(As04)2 7778-44-1 Arsenic acid calcium salt;
calcium orthoarsenate; tricalcium
arsenate; Chipcal; Pencal; Spracal
Cupric C4H6As6Cu4O16 12002-03-8 (Acetato) trimetaarsenitodicopper;
acetoarsenite bis(acetato)hexametaarseni-
totetracopper; copper acetate
arsenite; Paris green, emerald
green, French green, mineral green,
imperial green
Gallium arsenide AsGa 1303-00-0 Gallium monoarsenide
Lead arsenate PbHAs04 7784-40-9 Arsenic acid lead salt; acid lead
arsenate; acid lead ortho-arsenate;
arsenate of lead; arsinette; lead
acid arsenate; plumbous arsenate;
schultenite; standard lead
arsenate; Gypsine; Soprabel;
Talbot
Potassium arsenate KH2As04 7784-41-0 Arsenic acid monopotassium salt;
monopotassium arsenate;
monopotassium dihydrogen arsenate;
potassium acid arsenate; potassium
arsenate, monobasic; potassium
dihydrogen arsenate; potassium
hydrogen arsenate; Macquer's salt
Potassium arsenite KH(As02)2 10124-50-2 Arsenenous acid, potassium salt;
arsenious acid, potassium salt;
arsonic acid, potassium salt;
potassium metaarsenite; Fowler's
solution
Sodium arsenate3 Na3As04 7631-89-2 Arsenic acid, sodium salt; arsenic
acid, sodium ortho-arsenate;
sodium metaarsenate
Sodium arsenite NaAs02 7784-46-5 Arsenenous acid, sodium salt;
arsenious acid, sodium salt;
sodium metaarsenite; sodanit;
prodalumnol
1 The name "arsenic acid" is commonly used for the pentoxide as well as for the
various hydrated products.
2 Sometimes erroneously called "arsenic".
3 The name "sodium arsenate" is applied both to the disodium and the trisodium
salts.
1.2 Physical and chemical properties
Arsenic compounds are often unstable, and in many cases are not
well-defined materials. For example, the arsenites of the alkali
metals are slowly converted in solution to arsenates, by atmospheric
oxygen. Arsenic trisulfide reacts vigorously with oxidizing agents,
and hydrogen sulfide is generated on contact with strong acids.
Arsenic trichloride is highly reactive with water, strong oxidants,
ammonia, and some alkalis; the reaction results in the generation of
hydrogen chloride and chlorine gas.
Inorganic arsenic compounds may generate highly toxic (and flammable)
arsine gas when in contact with acids plus reducing metals (e.g.,zinc
or iron), or with sodium hydroxide plus aluminium. Some physical
properties are summarized in Table 2.
1.3 Analysis
The techniques most commonly used for the determination of arsenic
involve its transformation into arsine. Subsequent measurements of
arsine are carried out using spectrophotometry, flame and
electrothermal devices for atomic absorption spectroscopy (AAS),
atomic fluorescence (AFS), or atomic emission spectroscopy (AES). The
limit of detection for AAS is in the range of 2-20 ng/kg.
1.4 Composition
Arsenic is available as a technical grade product, usually with a
typical purity of 99%, and as a high-purity grade for semiconductor
use, with a purity of at least 99.999%. Arsenic pentoxide is usually
available as technical grade. Arsenic sulfide is available in some
countries as optical grade (99.999%), as well as a powder (99%
active). Arsenic trioxide is marketed as a 95%-pure, crude grade, and
as a 99%-pure, refined grade, as well as a 1% solution in about 5%
hydrochloric acid.
Commercial calcium arsenate usually contains about 60% calcium
arsenate and 10% calcium arsenite. Lime and calcium carbonate are
often also present. Lead arsenate is available as acid lead arsenate,
which contains 33% arsenic pentoxide. It is sometimes available as a
wettable powder (94-98%), as a dust or as a paste.
Potassium and sodium arsenates are generally available in purified as
well as reagent grades. Potassium arsenite is marketed by chemical
suppliers in a purified grade. It is also available, in some
countries, in a 1% aqueous solution known as Fowler's solution.
Sodium arsenite is available commercially in some countries as a pure
grade material of 95-98% purity, and in a technical grade of 90-95%
purity. It was previously used as powders containing 90 or 94% of the
chemical, and as solutions containing various concentrations (a 0.25%
solution was available for use as a livestock dip, but most solutions
contained 40-44% active ingredient).
Table 2. Some physical properties of inorganic arsenic compoundsa
Compound Vapour Melting Boiling Description Solubility
pressure point point (g/litre)
(mmHg) (°C) (°C)
Arsenic 1 at 817 615 grey, crystalline insoluble in water;
372 °C (28 atm) (sublimes) solid with soluble in HN03
metallic luster
Arsenic - 315 - white hygroscopic soluble in cold
pentoxide (decomp.) powder water (1500);
soluble in hot
water (767)
Arsenic - 300-325 707 yellow-red powder insoluble in cold
sulphide water (0.0005);
slightly soluble
in hot water;
soluble in
alkali, acids,
ethanol
Arsenic 10 at 16 130 oily, colourless decomposed by
trichloride 23.5 °C liquid with water; soluble
acrid smell in ethanol,
ether, conc.
mineral acids
Arsenic 66.1 at 312 465 white, amorphous soluble in
trioxide 312 °C or crystalline cold water, (12);
powder hot water (115);
alkali and HCl
Calcium 0 1455 decomp. colourless, soluble in
arsenate amorphous powder water (0.13);
soluble in dilute
acids
Cupric - n.a. n.a. emerald green, insoluble in
acetoarsenite crystalline water, soluble
powder in acids
Gallium - 1238 n.a. dark grey insoluble in
arsenide crystals water
Lead - 720 decomp. white, slightly soluble
arsenate (decomp.) crystalline in hot water;
solid soluble in HN03,
caustic alkalis
Compound Vapour Melting Boiling Description Solubility
pressure point point (g/litre)
(mmHg) (°C) (°C)
Potassium - 288 - white, soluble in
arsenate crystalline cold water, (190);
powder very soluble in
hot water; soluble
in acid, glycerol,
ammonia
Potassium - 300 - white powder soluble in water;
arsenite (decomp.) slightly soluble
in ethanol
Sodium - 86 - white powder soluble in cold
arsenate water, (389);
dodecahydrate ethanol, glycerol
Sodium - n.a. n.a. grey-whitish very soluble in
arsenite powder water; slightly
soluble in ethanol
a n.a. = not available.
decomp. = decomposes.
1.5 Production and uses
World production of arsenic, as arsenic trioxide, has been estimated
at around 60 000 tonnes annually; it has been estimated that about
one-third is used for wood preservation. Metallic arsenic is
currently used in alloys, in combination with lead and copper, in
semiconductor devices, and in low-melting point glasses. The most
important use of arsenic(III) oxide is in the manufacture of a variety
of insecticides, herbicides, fungicides, algicides, sheep dips, and
pharmaceutical products (Fowler's solution). Arsenic sulfide is used
for dehairing skins in tanning, in the manufacture of pyrotechnics and
semiconductors, and in the manufacture of special optical glass.
Calcium and lead arsenates have been used as insecticides, e.g., for
the control of boll weevil and gypsy moth, but these arsenates have
been largely replaced for this purpose by more effective organic
chemicals. However, in many countries, lead arsenate is still used as
an insecticide on fruit trees, vegetables, rubber, coffee, cacao, and
grapefruit, and as a herbicide for the treatment of turf. Arsenic (as
lead or calcium arsenate) is not a normal constituent of the
fungicidal Bordeaux mixture (calcium hydroxide and copper sulfate),
but it has occasionally been added to widen its action to control some
insects. Sodium arsenite has been used in cattle and sheep dips, for
debarking trees, and for non-selective weed control.
Arsenic-containing wood preservatives are widely used and usually
consist of a chromated copper arsenate, applied under pressure.
2. SUMMARY AND EVALUATION
2.1 Natural occurrence and biological transformations in the
environment
As a result of its natural occurrence, humans are universally exposed
to arsenic in various forms. The various naturally occurring
inorganic and organic arsenic compounds are interlinked through
complex biotic and abiotic transformations in the environment.
Inorganic arsenic is found chiefly in the form of its compounds with
metals (arsenides), which usually occur in isomorphous mixture with
sulfides. High levels of arsenic may also be present in some coals
(up to 1500 mg/kg). As a result of the presence of arsenic in the
parent rock, arsenic is present naturally in soils in various
quantities. Soils overlying sulfide-ore deposits may contain several
hundred mg/kg. Arsenic is more strongly bound to soils that have a
high clay or high organic matter content and, in these circumstances,
is less available to plants. Arsenic is phytotoxic. Plants take up
arsenic in proportion to the soil concentration, except at very high
soil concentrations. Plants growing on mine or smelter wastes have
developed resistance to arsenic toxicity; such plants sometimes have
concentrations of arsenic (6000 mg/kg has been found) that may be
toxic to animals eating the plants. Arsenic taken up by plants is
distributed to all tissues.
Inorganic arsenic can be converted to methylated species in soil by a
number of microorganisms under aerobic, as well as anaerobic,
conditions. In anoxic parts of the soil layer, arsenic can be
immobilized as the sulfide. Arsenic is present in water at a
concentration that varies greatly. Extremely high levels of inorganic
arsenic have been found in some ground waters. Arsenic in aquatic
systems partitions preferentially to the sediment.
A number of microorganisms (e.g., fungi and bacteria in soil, algae in
water) have the capacity to methylate inorganic arsenic to the much
less acutely toxic compounds methane-arsonic acid and dimethylarsinic
acid (cacodylic acid); the latter is readily converted in soil to the
volatile methylarsines. Algae (unicellular organisms and seaweeds)
actively take up naturally occurring arsenate, and transform inorganic
arsenic into a variety of organic arsenic compounds. The
bioconcentration of arsenic in unicellular algae has been reported to
reach up to 3000 times the concentration in the surrounding water.
This is a major source of arsenic for higher organisms. Fish and
crustaceans accumulate arsenic compounds via the food-chain, in the
form of arsenocholine and arsenobetaine. Arsenobetaine is
metabolically very stable and is bioaccumulated in the higher trophic
levels of the aquatic food-chains. Marine fish and crustaceans
commonly contain 2-20 mg arsenic/kg - mainly as organic arsenic - on a
wet weight basis, although higher values have been reported (up to
50-100 mg/kg).
2.2 Human exposure
Exposure of the general population occurs mainly through arsenic
present in food and drinking-water. In some areas, the natural high
arsenic content of the drinking-water has caused endemic, chronic
arsenic poisoning. A significant portion of the population in other
areas is exposed to arsenic levels in drinking-water that lie above
the present WHO drinking-water guideline value for arsenic of
50 µg/litre. In humans, the total daily intake of arsenic is greatly
influenced by the amount of seafood in the diet, and consumers may
reach several thousand µg of total arsenic per day. However, 85-95%
of the arsenic present in marine products is present as the much less
toxic, organic arsenic compounds.
In the working environment, if precautions are not taken, high
inhalation exposures may be associated with the smelting of
non-ferrous sulfide ores, glass manufacturing, wood preservation
plants, and the agricultural application of arsenic-containing
pesticides.
2.3 Effects on organisms in the environment
For most aquatic animal species, the acute toxicity of inorganic
arsenic compounds is moderate to low (LC50 10-100 mg/litre).
However, long-term exposure of immature fish populations to sublethal
doses may result in toxic effects at about 4 mg/litre, and exposure of
Daphnia may lead to slightly impaired reproduction at 0.5 mg/litre.
In aquatic ecosystems, algal communities seem to suffer most from
exposure to arsenic. The growth of some species of unicellular algae
is inhibited at arsenate concentrations as low as 75 µg/litre.
Communities of some species of marine macro algae (seaweed) may be
eliminated at exposures of about 10 µg/litre. Arsenic is also toxic
to terrestrial plants.
2.4 Uptake, metabolism, and excretion
Studies on experimental animals, as well as on humans, have shown that
over 90% of an ingested dose of dissolved inorganic trivalent or
pentavalent arsenic is absorbed from the gastrointestinal tract. In
the lungs, water-soluble compounds, such as oxides and arsenites, are
rapidly absorbed, whereas there may be considerable retention of
arsenic compounds of low solubility. Since inorganic arsenic
compounds are considered to be poorly absorbed through the skin
(except for corrosive compounds like arsenic trichloride), in the work
environment, dermal exposure is usually of less significance than
inhalation exposure.
Although high levels of arsenic are maintained for long periods of
time in the bone, hair, and nails of exposed individuals, most
inorganic arsenic is eliminated at a much higher rate with the urine,
mainly as dimethylarsinic acid and methane-arsonic acid. Depending on
the administered dose, the half-life in man, after short-term
exposure, is in the range of 1-3 days. There is no long-term
accumulation of arsenic in soft tissues. Placental transfer of
inorganic arsenic has been demonstrated in both experimental animal
and human studies.
With increasing arsenic intake, the proportion of arsenic detoxified
(methylated) is reduced. Increases in the inorganic arsenic body
burden may be expected at daily intakes exceeding about 200 µg/person.
The level at which overloading of the detoxification system occurs may
be lowered by a protein-deficient diet. In persons with a low
(stable) dietary arsenic intake, the urinary levels may be used to
monitor exposure to inorganic arsenic. Since the elimination of
arsenic takes place mainly via the kidneys, the concentration of
arsenic in the urine is a good indication of exposure to inorganic
arsenic.
2.5 Effects on experimental animals
In general, the toxic action of arsenic in experimental animals
resembles that seen in man. The oral LD50 of arsenic ranges from
15 to 293 mg/kg body weight in rats, and from 11 to 150 mg/kg body
weight in other experimental animals. Trivalent arsenic is, in
general, more toxic than pentavalent arsenic. With long-term oral
administration, liver lesions, anaemia, and pathological skin changes
have been produced in animal models. Studies on experimental animals
have demonstrated the development of tolerance towards the acute
effects of arsenic compounds.
There has been no consistent demonstration of carcinogenicity in tests
with several species of animals, when various chemical forms of
arsenic have been administered by the oral route, or to the skin.
Teratogenic effects have been induced in pregnant golden hamsters
given a high dose by either intravenous or intraperitoneal injection.
Available mutagenicity data are equivocal; however, inorganic arsenic
compounds have been shown to enhance the potency of other mutagenic
agents.
2.6 Effects on humans
In man, the smallest recorded fatal dose is in the range of 70-180 mg,
but recovery has been reported after much larger doses. Acute
symptoms develop within 30 minutes to 2 hours, in the form of a sudden
and explosive gastroenteritis. Common symptoms include: nausea,
vomiting, abdominal pain, rice-water diarrhoea (which develops into
bloody stools), progressive general weakness, and severe dehydration
leading to collapse and heart failure. The patient complains of a
metallic taste, salivation, hoarse voice, constriction of the throat,
and difficulty in swallowing. The skin is pale and moist, and the
stomach may be distended. Severely poisoned patients develop shock as
a result of increased capillary permeability and loss of fluids and
electrolytes. Death usually results from heart failure within 24
hours to 4 days. If the patient survives, hepatic and renal
impairment and central nervous and peripheral nervous system damage
may become evident. The sequelae of acute poisoning include loss of
hair (which grows back with recovery) and brittle fingernails with
white horizontal striae ("Mees" lines). Peripheral nervous
disturbances, primarily of a sensory type, are frequently encountered
in individuals surviving poisoning, and there may also be transient
effects on the blood constituents. Irritant and vesicant arsenic
compounds, such as arsenic trioxide and arsenic trichloride, have been
known to cause severe damage to the respiratory system following
inhalation.
Tolerance to arsenic can develop after repeated exposure. The chronic
signs of toxicity are insidious and may be difficult to diagnose.
They are chiefly related to the skin, gastrointestinal tract, and
nervous system, but also to the mucous membranes, lungs, and liver.
Signs of poisoning are: progressive general weakness, anorexia,
nausea, vomiting, stomatitis, colitis, salivation, nose bleed and
bleeding gums, conjunctivitis, "Mees" lines, thirst, runny nose,
hoarseness, dermatitis, severe skin exfoliation, low-grade fever, and
weight loss. The following signs and symptoms might also be observed:
garlic odour of breath, motor paralysis, tingling of the skin of
extremities, foot and wrist drop, tremors, severe pain and ataxia, and
loss of hair. Perforation of the nasal septum may be helpful in the
diagnosis of chronic poisoning caused by inhalation of inorganic
arsenic. A major symptom of chronic poisoning by arsenic is a
symmetrical hyperkeratosis of the palms and soles, as well as
melanosis. The skin changes may progress and cover the entire body in
multiple forms, and eventually develop into skin cancer (mostly
squamous cell epithelioma). In certain populations, a vascular
disorder resulting in gangrene of the lower extremities ("Blackfoot
disease") has also been observed. An allergic type of contact
dermatitis is frequently seen among workers who are exposed to arsenic
trioxide. A common finding among arsenic-exposed workers is
conjunctivitis and perforation of the nasal septum as a result of
irritation of the upper respiratory organs by arsenic dust.
In a number of studies of populations of smelter workers, as well as
of pesticide applicators, a clear association between occupational
arsenic exposure and an increased incidence of lung cancer has been
established. The carcinogenic effect of arsenic taken up by
inhalation is potentiated by smoking, and possibly also by other
agents present in these occupational environments.
As to the chronic toxic effects caused by oral intake, it appears that
the ingestion of 3 mg of inorganic arsenic per day, over a period of a
few weeks, may give rise to severe poisoning in infants, and symptoms
of toxicity in adults. Chronic arsenic poisoning, with skin lesions,
is often accompanied by moderate anaemia and leukopenia. Chronic
signs of intoxication may persist for several years after the
cessation of exposure.
3. CONCLUSIONS AND RECOMMENDATIONS
3.1 Conclusions
Exposure of the general population to arsenic compounds occurs
predominately via food and drinking-water. Over-exposure in the
working environment and during agricultural application occurs mainly
through inhalation.
The acute toxicity of inorganic arsenic compounds for man is very
high. The smallest, fatal, single dose for a human is in the range of
70-180 mg. With long-term exposure, significant toxic effects can be
expected to occur above a daily oral intake of 100-200 µg.
The main chronic effects of inorganic arsenic compounds are damage to
the nervous system and hyperkeratosis of the skin, leading to skin
cancer.
Inorganic arsenic is a proven human carcinogen after long-term oral
intake, as well as after inhalation.
Arsenic is moderately toxic for fish and aquatic invertebrates, but is
highly toxic for some algal species. There is field evidence of
arsenic affecting aquatic ecosystems.
3.2 Recommendations
To minimize the risk to humans, the use of inorganic arsenic compounds
as pesticides should be stopped, wherever this is feasible.
Occupational exposure should be kept to a minimum.
Regularly exposed workers should be kept under strict medical
surveillance.
A daily oral intake of 2 µg of inorganic arsenic/kg body weight should
not be exceeded.
The medicinal use of inorganic arsenic compounds, in particular
potassium arsenite (Fowler's solution), is to be strongly discouraged.
4. HUMAN HEALTH HAZARDS, PREVENTION AND PROTECTION, EMERGENCY ACTION
4.1 Human health hazards, prevention and protection, first aid
4.1.1 General population
Where populations are exposed to naturally occurring arsenic in water,
every effort should be made to provide drinking-water of better
quality.
4.1.2 Occupationally exposed population
In order to interrupt the chain of generation/release/transmission of
the hazardous agent, the main goal should be primary prevention
through interventions in the work environment. These should include
such measures as exhaust ventilation, closed systems, enclosure of
sources, and good housekeeping practices. Local exhaust ventilation
systems must include air cleaning devices, to prevent environmental
pollution.
When these measures are not technically feasible, as is the case in
the formulation and application of pesticides, or during temporary
operations, the use of personal protective clothing and equipment
(e.g., disposable dust masks) is recommended.
Respirators must be appropriately selected, used, and maintained. In
the case of arsenic compounds in a particulate form, a respirator for
particles should be used; however, when arsine is formed
accidentally, this type of respirator is completely ineffective.
Routine cleaning and maintenance of respirators is essential,
including the renewal of filters or cartridges. This requires proper
supervision and training of workers, and adequate facilities. The
exposure limits adopted should be strictly observed.
Safe work practices are important preventive measures, particularly
when the way a task is performed may influence the generation or
release of the agent, or may influence exposure. In the case of
arsenic compounds, conditions that can lead to the accidental
generation of arsine must be spelled out in the work practices, as
well as ways of preventing such generation.
The following precautions should be observed during handling and use:
* Avoid contact with the skin and eyes, by using a face-mask and
complete protective clothing.
* Do not smoke, drink, or eat in the workplace. Wash the hands and
any exposed skin before eating, drinking, or smoking, and after
work.
Regular medical supervision of workers occupationally exposed to
arsenic is recommended. For employees exposed for 10 years or more,
examinations should be repeated every 6 months. Owing to its
corrosive properties, skin contact with arsenic trichloride is
associated with a high risk of systemic intoxication.
Surveillance programmes should include:
* routine air monitoring, to ensure that air concentrations are
below the acceptable standards;
* biological monitoring, by measuring arsenic concentrations in the
urine.
Interpretation of results must take into consideration
non-occupational values and, therefore, pre-exposure values.
4.1.3 First aid
Medical attention should be obtained as soon as possible. In the
meantime, first aid should be commenced. If material has been spilled
on the skin, immediately remove the patient from the source of
contamination, remove all contaminated clothing, and wash affected
areas with soap and water. If the material is in the eyes, flush with
clean water for at least 15 minutes. In case of ingestion, immediate
action is imperative: if the patient is conscious, give two glasses
of milk (or water), or a beaten egg, induce vomiting and subsequently
administer activated charcoal, if possible. Transport the patient to
a hospital.
4.2 Advice to physicians
Diagnosis is based on history, symptoms, signs, and laboratory
investigations, but treatment should start on suspicion of poisoning.
4.2.1 Treatment
Prognosis is dependent on dose, as well as the time between ingestion
of arsenic and first treatment. Gastric aspiration and lavage with
warm water followed by sodium sulfate (30 g) is indicated. Keep
patient warm and quiet; combat shock and dehydration. Apply
artificial respiration, oxygen therapy, whole blood, or fluids as
needed. Dimercaprol (BAL) by intra-muscular injection has been found
to be useful in cases of intoxication. A number of side-effects have
been associated with BAL, and the use of this antidote for treatment
of chronic intoxications is controversial. D-penicillamine has also
been used, although its efficacy has been questioned. A water-soluble
analogue of dimercaprol (meso-2,3-dimercaptosuccinic acid or DMSA) has
proved to be more effective and less toxic; therefore, it is indicated
as first choice chelator, if available. The sodium salt of
2,3-dimercaptopropanesulfonate (Unithiol, Dimaval, DMPS) has also been
reported to be effective and to induce less severe side-effects, in
comparison with dimercaprol.
4.3 Explosion and fire hazards
Finely divided arsenic metal may present an explosion risk. Most
industrially important inorganic arsenic compounds are not
combustible, but may evolve highly toxic and flammable arsine when
heated, or in the presence of other agents (see section 1.2). Arsine
may also be produced when arsenic is in contact with acids in the
presence of some metals, e.g., zinc or iron, as a consequence of the
liberation of hydrogen. Arsenic sulfides are combustible and yield
toxic and flammable hydrogen sulfide gas on contact with strong acids.
Do not use water to extinguish fires involving arsenic trichloride;
dry chemical or carbon dioxide extinguishers should be used.
Water sprays should only be used to cool undamaged stock; the use of
large amounts of water should be avoided because of the possibility of
highly toxic run-off from the site. Fire service personnel should be
advised that self-contained breathing apparatus and totally
encapsulated protective clothing are necessary.
4.4 Storage and transport
All products should be stored in secure buildings, kept dry and out of
the reach of children and animals, and separated from food and animal
feed. Containers should be sound and adequately labelled. Arsenic
trichloride is highly corrosive and must not be stored in containers
made from steel, galvanized steel, tin, or aluminium. Suitable
containers are high density polyethylene bottles, resin-lined metal
drums, and glass containers. Do not store near fertilizers, seeds,
insecticides, or fungicides.
These products should be transported in a separate compartment to
prevent contamination of food or feed.
4.5 Spillage
Keep spectators away from any leakage. Prevent contamination of other
goods or cargo, nearby vegetation, and surface waters. Absorb
spillage of liquid products with sand or earth, sweep up and place in
a separate container. Empty any product remaining in damaged or
leaking containers into a clean empty container, which should be
suitably labelled. Sweep up any spilt powder with damp sawdust,
taking care not to raise a dust cloud. Place in a separate container
for subsequent disposal. Contaminated absorbents, used containers,
surplus product, etc., should not be incinerated.
4.6 Disposal
Arsenic-containing wastes should not be buried in landfill sites,
except in very small quantities interspersed with large volumes of
non-hazardous wastes. Do not incinerate and do not discharge to
sewers or water courses.
Precipitation and/or solidification are preferred methods but should
be carried out by a specialist in toxic waste disposal, because of the
persistence and toxicity of arsenic.
5. HAZARDS FOR THE ENVIRONMENT AND THEIR PREVENTION
Inorganic arsenic compounds are moderately toxic for fish and aquatic
invertebrates. They are highly toxic for some algae. Low
concentrations have been shown to have serious effects on aquatic
ecosystems. Biological transformation results in the production of
less acutely toxic organic arsenic compounds. Inorganic arsenic in
sediments may be released slowly over long periods. Groundwater
contamination has proved to be a serious problem in some areas.
Although persistent and taken up by plants and other organisms,
inorganic arsenic as such is not subject to significant biological
transfer through food-chains.
6. CURRENT REGULATIONS, GUIDELINES, AND STANDARDS
6.1 Previous evaluations by international bodies
The Joint FAO/WHO Expert Committee on Food Additives assigned a
provisional tolerable weekly intake (PTWI) of 0.015 mg/kg body weight
for inorganic arsenic, but stressed that there is a narrow margin
between the PTWI and intakes reported in epidemiological studies to
have toxic effects.
Arsenic trioxide has a minimum lethal dose for humans of 2 mg/kg body
weight, and is classified in The WHO recommended classification of
pesticides by hazard and guidelines to classification as an "extremely
hazardous pesticide", the oral LD50 for the rat being 180 mg/kg body
weight.
The International Agency for Research on Cancer (IARC) evaluated
arsenic and (inorganic) arsenic compounds and concluded that there is
sufficient evidence of their carcinogenicity in humans, and limited
evidence of their carcinogenicity in experimental animals (Group 1).
Because of the inadequacy of the data, and the concern over the
potential carcinogenicity of arsenic, no acceptable daily intakes
(ADI) for calcium and lead arsenate pesticides have been established
by the Joint FAO/WHO Meeting on Pesticide Residues.
A guideline value of 0.05 mg As(total)/litre has been recommended in
the WHO Guidelines for drinking-water quality. In the WHO Air
quality guidelines for Europe it was concluded that, because
inorganic arsenic is carcinogenic and there is no known safe
threshold, no safe level for arsenic can be recommended. At an
arsenic air concentration of 1 µg/m3, a conservative estimate of
lifetime risk is 3 × 10-3.
6.2 Exposure limit values
The information given in this section has been extracted from the most
recent International Register of Potentially Toxic Chemicals (IRPTC)
legal file. Regulatory decisions about chemicals, taken in a certain
country, can only be fully understood in the framework of the
legislation of that country. The regulations and guidelines of all
countries are subject to change and should always be verified with
appropriate regulatory authorities before application. Some exposure
limit values are given in Table 3.
6.3 Specific restrictions
No arsenic-containing pesticides (except for wood preservatives) or
pharmaceutical products are permitted in Sweden. Lead arsenate has
been prohibited from use as an insecticide in Japan since 1977.
In Germany, emissions of arsenic are controlled. The total
concentration of dusts of arsenic, cobalt, nickel, selenium, and
tellurium, including their inorganic compounds, may not exceed
1 mg/m3 at a mass flow of 5 g/hour or more.
In the United States of America, arsenic and compounds are classified
as toxic pollutants, for which the US Environmental Protection Agency
is required to set effluent limitations and pre-treatment standards
for 21 major industries. Permits are required for the discharge of
arsenic into USA national waters. Arsenic in outfalls must be
reported. Inspection, monitoring, and reporting requirements after
the issue of the permit are specified. Even if not required in the
permit, discharge of arsenic must be reported if it exceeds the higher
of the following levels: (a) 100 µg/litre; (b) five times the
maximum concentration reported in the application; (c) the level
established by the US EPA.
6.4 Transport and labelling
The United Nations Committee of Experts on the Transport of Dangerous
Goods has classified arsenic and most inorganic arsenic compounds as
"Poisonous (toxic) substances". As such, strict regulations are
applied to their transportation. The International Maritime Dangerous
Goods code classifies such substances as marine pollutants, which
require appropriate warning labels.
Within the European Economic Community, the mandatory labelling of
arsenic, which is classified as "Toxic", includes the "skull and
crossbones" design. The label should read "Toxic by inhalation and if
swallowed", as well as:
Keep locked up, keep out of reach of children. When using do
not eat, drink, or smoke. After contact with skin, wash
immediately with plenty of .... (to be specified by the
manufacturer). If you feel unwell, seek medical advice (show the
label where possible).
Within the European Economic Community legislation, arsenic trioxide
is classified as a carcinogen
Class 1 (known human carcinogen) requiring the label:
May cause cancer; very toxic if swallowed; causes burns; avoid
exposure, obtain special instructions before use; in case of
accident or if you feel unwell, seek medical advice
immediately (show label where possible).
Table 3. Exposure limit values
Medium Specification Country/ Exposure limit description Value
organization (mg/m3)
Air Occupational Argentina Maximum permissible limit (MPC)
- Time-weighted average 0.5
Australia Threshold limit value (TLV)
- Time-weighted average (TWA) 0.2
Belgium Threshold limit value (TLV)
- Time-weighted average (TWA) 0.2
Canada Threshold limit value (TLV)
- Time weighted average (TWA) 0.2
Czechoslovakia Maximum allowable concentration (MAC)
- Time-weighted average (TWA) 0.2
Finland Maximum permissible limit (MPC)
- Time-weighted average (TWA) 0.01
Germany Technical guiding concentration (TRK)
- 8h - Time-weighted average (TWA) 0.1
Hungary Maximum allowable concentration (MAC)
- Time-weighted average (TWA) 0.3
Air Occupational Italy Threshold limit value (TLV) (carcinogen) 0.25
Netherlands Maximum limit (MXL)
- Time-weighted average (TWA) 0.5
Medium Specification Country/ Exposure limit description Value
organization (mg/m3)
Air Occupational Poland Maximum permissible limit (MPC)
- Time-weighted average (TWA) 0.3
Romania Maximum permissible limit (MPC)
- Time-weighted average (TWA) 0.2
Sweden Hygienic limit value (HLV)
1 day- Time-weighted average (TWA) 0.03
United Kingdom Permissible exposure limit (PEL)
8h - Time-weighted average (TWA) 0.2
USA Threshold limit value (TLV)
- Time-weighted average (TWA) 0.2
USSR Maximum allowable concentration (MAC)
- Time-weighted average (TWA) 0.01
Yugoslavia Maximum allowable concentration (MAC)
- Time-weighted average (TWA) 0.01
Air Ambient Czechoslovakia Maximum allowable concentration (MAC
- average/day 0.003
- average/0.5h 0.01
USSR Maximum allowable concentration (MAC)
- average/day 0.003
Water Drinking- Canada Maximum allowable concentration (MAC) 0.05 mg/litre
Czechoslovakia Maximum allowable concentration (MAC) 0.05 mg/litre
Germany Maximum permissible limit (MPC) 0.04 mg/litre
Medium Specification Country/ Exposure limit description Value
organization (mg/m3)
Water Drinking- Japan Maximum permissible limit (MPC) 0.05 mg/litre
USA Maximum permissible limit (MPC) 0.05 mg/litre
USSR Maximum allowable concentration (MAC) 0.05 mg/litre
WHO Guideline level (GL) 0.05 mg/litre
EEC Maximum allowable concentration (MAC) 0.05 mg/litre
Water Surface Czechoslovakia Maximum allowable concentration (MAC) 0.5 mg/litre
Japan Maximum limit (MXL) 0.05 mg/litre
Mexico Maximum permissible limit (MPC)
(depending on water use) 0.05-5.0 mg/litre
USSR Maximum allowable concentration (MAC) 0.05 mg/litre
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