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Chloroform

DESIGNATIONS

CAS No.: 67-66-3
Registry name: Chloroform
Chemical name: Trichloromethane
Synonyms, Trade names: Methyl trichloride, methane trichloride, formyl trichloride, Haloform, R20
Chemical name (German): Chloroform, Trichlormethan
Chemical name (French): Chloroforme
Appearance: clear, colourless, highly refractive liquid with sweet odour

BASIC CHEMICAL AND PHYSICAL DATA

Empirical formula: CHCl 3
Rel. molecular mass: 119.4 g
Density: 1.48 g/cm3
Relative gas density: 4.12
Boiling point: 61C
Melting point: -63C
Vapour pressure: 21 x 103 Pa
Solvolysis/solubility: in water: 8.1 g/l

miscible with solvents such as benzene, pentane, hexane, ethanol and diethyl ether

Conversion factors: 1 ppm = 4.96 mg/m3

1 mg/m3 = 0.20 ppm

ORIGIN AND USE

Usage:
Most of the total production of chloroform is used to produce monochlorodifluoromethane (CFC22) which is used as a refrigerant but also as an intermediate in the manufacture of tetrafluoroethene which then may be polymerised (PTFE). Chloroform is also used in the production of dyes, pharmaceuticals and pesticides. Its use as a solvent and application in anaesthesia is rapidly on the decline.

Origin/derivation:
90 - 95 % of chloroform is produced either by the hydrochlorination of methanol or by the chlorination of methane. 5 - 10 % is of natural origin and found in seawater (reaction of methyl iodide with inorganic chlorine). Chlorine bleaching of cellulose produces large quantities of chloroform. Considerable amounts likewise result from water chlorination. Commercially available chloroform contains, amongst other substances, bromochloromethane, bromodichloromethane, methylene chloride, tetrachloromethane, 1,2-dichloroethane, trichloroethylene and tetrachloroethane as contaminants.

Production figures:

Worldwide 1973: 245,000 - 300,000 t acc. KOCH, 1989
D 1982: 35,500 t acc. UBA, 1986

Emissions:
The production and application-related emissions amount to some 10,000 t; this is supplemented by annual impacting of surface and groundwater with a further 10,000 t/a (acc. KOCH, 1989).

Toxicity

Humans: 5,000 mg/m3 after 7 min. dizziness, head congestion acc. BUA, 1985
20,000 mg/m3 feeling faint acc. BUA, 1985
69,440 mg/m3 deep full anaesthesia acc. BUA, 1985
> 79,360 mg/m3 apnoea, death acc. BUA, 1985
LDLo 10 ppm, inhalation (1 a) acc. KOCH, 1989
Mammals:
Rat: LD50 1,194 mg/kg, oral acc. DVGW, 1988
LCLo 8,000 ppm, inhalation (4 h) acc. BUA, 1985
Mouse: LD50 80 mg/kg, oral acc. BUA, 1985
LD50 28,000 mg/kg, inhalation acc. BUA, 1985
Dog: LD50 1,100 mg/kg, oral acc. DVGW, 1988
Rabbit: LDLo 500 mg/kg, oral acc. BUA, 1985
Guinea pig: LCLo 20,000 ppm, inhalation (2 h) acc. BUA, 1985
Aquatic organisms:
Golden orfe: LC50 162-191 mg/l (48 h) acc. UBA, 1986
Rainbow trout: LC50 18-66.8 mg/l (96 h) acc. UBA, 1986
Blue perch: LC50 18-115 mg/l (96 h) acc. UBA, 1986
Water flea: LC50 28.9 mg/l (48 h) acc. UBA, 1986

Characteristic effects:

Humans/mammals: Intake is most frequently by inhalation with some of the substance being resorbed in the lungs and the remainder being exhaled. Oral application likewise results in the majority being exhaled or discharged by the kidneys.

Chloroform damages the liver and the kidneys, the central nervous system and the heart. Large doses have a narcotic effect.

Chloroform has proved to be carcinogenic in animal experiments. Mutagenic or teratogenic effects have not been established to date.

ENVIRONMENTAL BEHAVIOUR

Water:
The degradation of chloroform in water is extremely slow (water hazard class 3). The high volatility results in degasification over surface water. Bioaccumulation is minimal despite the high fat solubility of chloroform (bioconcentration factor in fish: 6; UBA, 1986).

Air:
Chloroform ingresses into the atmosphere because of its high volatility and is accumulated there in small quantities. The substance is decomposed by photolysis.

Soil:
There is no adsorption on particles thus precluding the possibility of accumulation in soil or sediment.

Degradation, decomposition products:
Biological degradation under anaerobic conditions results in carbon dioxide, chloride and methane; degradation in the organism produces carbon dioxide, chloride and phosgene. The presence of oxidising agents causes chloroform to decompose with phosgene and hydrochloric acid being formed (DVGW, 1988).

Food chain:
Chloroform is ubiquitous and thus may also be found in foodstuffs. Drinking water sometimes contains high chloroform concentrations caused by water chlorination. The daily chloroform absorption is estimated at an average of 10 m g/person with one quarter each resulting from drinking water and foodstuffs and the other half from the atmosphere (DVGW, 1988).

ENVIRONMENTAL STANDARDS

Medium/ acceptor Sector Country/ organ.

Status

Value Cat. Remarks Source
Water: Surface D/NL

(L)

1 mg/l IAWR For natural treatment acc. DVGW, 1988
Surface D/NL

(L)

5 mg/l IAWR For phys.-chem. treatment acc. DVGW, 1988
Drinkw CDN

(L)

350 g/l   1978 acc. DVGW, 1988
Drinkw CH

(L)

25 g/l   1) acc. DVGW, 1988
Drinkw D

(G)

25 g/l   BGA commission1) acc. DVGW, 1988
Drinkw USA

(L)

100 g/l   Sum of trihalomethanes acc. DVGW, 1988
Drinkw WHO

G

30 g/l     acc. DVGW, 1988
Air: Emiss. D

L

20 mg/m3   mass flow > 100 g/h acc. TA Luft, 1986
Foodstuffs:   D

L

25 g/l   Table, mineral water acc. DVGW, 1988

Notes:

1) Sum of chloroform, bromoform, bromodichloromethane, dibromochloromethane
2) Substance with a suspected carcinogenic potential
The use of chloroform in cosmetics, medicines and pesticides is banned in Germany

Comparison/reference values

Medium/origin Country Concentration Source
Water:
Rhine (Wiesbaden, 1986) D 0.35-2.1 g/l acc. DVGW, 1988
Rhine (Lobith, 1985) D 0.5-4 g/l acc. DVGW, 1988
Main (Sindlingen, 1983) D 21 g/l acc. DVGW, 1988
Moselle (1983) D 0.5-0.7 g/l acc. DVGW, 1988
Elbe (1983) D 0.6-9.8 g/l acc. DVGW, 1988
North Sea coast (Emden) D 0.56-3.8 g/l acc. UBA, 1986
Baltic coast D 0.06-0.17 g/l acc. UBA, 1986
Sediment:
Ruhr (1972-1981) D 1-3 mg/kg acc. DVGW, 1988
Air:
Basic atmospheric impact   0.05-0.1 g/m3 acc. KOCH, 1989
Urban areas   up to 74 g/m3 acc. KOCH, 1989

Assessment/comments

On account of its ubiquitous distribution and the considerable quantities emitted into the environment every year, chloroform has to be considered as an environmental hazard. There is no information to date on the effect and concentration in soils and soil organisms and the genotoxic potential likewise remains unclear. In particular, water chlorination should be avoided as far as possible in order to reduce the pollution of groundwater and drinking water without neglecting the necessity of hygienic prevention measures.


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