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DESIGNATIONS
CAS No.:
Registry name: Chlorophenols
Chemical name: Chlorophenols
Synonyms, Tradenames:
Chemical name (German): Chlorphenole
Chemical name (French): Chlorophénols
Appearance: colourless solids (except o-chlorophenol) with offensive odour
Note: The group of the chlorophenols consists of 19 different compounds. As pentachlorophenol (PCP) is the most important compound in this group, the basic chemical and physical data refer to PCP.
| CAS No.: | 87-86-5 |
| Registry name: | Pentachlorophenol |
| Chemical name: | Pentachlorophenol |
| Synonyms, Tradenames: | PCP, 2,3,4,5,6-Pentachlorophenol, Dowicide G, Dowicide 7, Penta, Santophen 20, Pentacon, Penchlorol, Pentakil, Sontobrite, Weedone |
| Chemical name (German): | Pentachlorphenol |
| Chemical name (French): | Pentachlorophénol |
| Appearance: | colourless solid with offensive odour |
BASIC CHEMICAL AND PHYSICAL DATA
| Empirical formula: | C6Cl5OH |
| Rel. molecular mass: | 266.35 g |
| Density: | 1.978 g/cm3 |
| Boiling point: | 300°C (decomposition) |
| Melting point: | 190°C |
| Vapour pressure: | 23 x 10-3 Pa |
| Solvolysis/solubility: | in water: 20 mg/l soluble in alcohol, ether, acetone, benzene |
| Conversion factors: | 1 ppm = 11.1 mg/m3 1 mg/m3 = 0.09 ppm |
ORIGIN AND USE
Usage:
Because of their broad-spectrum antimicrobial properties,
chlorophenols have been used as preservative agents for wood,
paints, vegetable fibres and leather and as disinfectants. In
addition, they are used as herbicides, fungicides and
insecticides and as intermediates in the production of
pharmaceuticals and dyes.
Origin/derivation:
Most of the commercially important chlorophenols are obtained by
direct chlorination of phenol using chlorine gas. In the
technical product, there are impurities of other chlorophenol
isomers or chlorophenols with more or less chlorine. The heavy
chlorophenols are mainly contaminated by
polychlorophenoxyphenols, chlorodibenzoparadioxins and
chlorodibenzofurans. Emissions are mainly due to the manufacture,
storage, transportation and application of chlorophenols.
Production figures:
| World (excluding former COMECON and China) | 100,000 t/a |
| heavy chlorophenols (4-5 chlorine atoms) | 35-40,000 t/a |
| light chlorophenols (1-3 chlorine atoms) | 60,000 t/a |
(figures taken from ULLMANN 1985)
Toxicity
| Humans: | LD 50-500 mg/kg, oral (estimated) | |
| Mammals: | ||
| Rat | LD50 670 mg/kg, oral (2-chlorophenol) | acc. ULLMANN 1986 |
| Rat | LD50 950 mg/kg, percutaneous (2-chlorophenol) | acc. ULLMANN 1986 |
| Rat | LD50 570 mg/kg, oral (3-chlorophenol) | acc. ULLMANN 1986 |
| Rat | LD50 1030 mg/kg, percutaneous (3-chlorophenol) | acc. ULLMANN 1986 |
| Rat | LD50 261 mg/kg, oral (4-chlorophenol) | acc. ULLMANN 1986 |
| Rat | LD50 1390 mg/kg, percutaneous (4-chlorophenol) | acc. ULLMANN 1986 |
| Rat | LD50 580 mg/kg, oral (2,4-dichlorophenol) | acc. ULLMANN 1986 |
| Rat | LD50 1730 mg/kg, percutaneous (2,4-dichlorophenol) | acc. ULLMANN 1986 |
| Rat | LD50 820 mg/kg, oral (2,4,5-trichlorophenol) | acc. ULLMANN 1986 |
| Rat | LD50 2260 mg/kg, percutaneous (2,4,5-trichlorophenol) | acc. ULLMANN 1986 |
| Rat | LD50 1620 mg/kg, oral (2,4,5-trichlorophenol, sodium salt) | acc. ULLMANN 1986 |
| Rat | LD50 820 mg/kg, oral (2,4,6-trichlorophenol) | acc. ULLMANN 1986 |
| Rat | LD50 140 mg/kg, oral (2,3,4,6-tetrachlorophenol) | acc. ULLMANN 1986 |
| Rat | LD50 210 mg/kg, percutaneous (2,3,4,6-tetrachlorophenol) | acc. ULLMANN 1986 |
| Rat | LD50 50 mg/kg, oral (pentachlorophenol) | acc. ULLMANN 1986 |
| Rat | LD50 100 mg/kg, percutaneous (pentachlorophenol) | acc. ULLMANN 1986 |
| Rat | LD50 210 mg/kg, oral (pentachlorophenol,sodium salt) | acc. ULLMANN 1986 |
| Rat | LD50 72 mg/kg, percutaneous (pentachlorophenol, sodium salt) | acc. ULLMANN 1986 |
| Aquatic organisms: | ||
| Golden orfe | LC50 0.60 mg/l (96 h), pentachlorophenol | acc. RIPPEN 1990 |
| Rainbow trout | LC50 0.12-0,26 mg/l (96 h), pentachlorophenol | acc. RIPPEN 1990 |
| Water flea | LC50 0.33-0.41 mg/l (96 h), pentachlorophenol | acc. RIPPEN 1990 |
| Bacteria (div.) | NOEC 12.3 mg/l (30 min), growth | acc. RIPPEN 1990 |
| Algae | EC50 10-7000 µg/l (96h), growth, pentachlorophenol | acc. RIPPEN 1990 |
Characteristic effects:
Humans/mammals: Chlorophenols can be absorbed through the lungs, the gastro-intestinal tract and the skin. Some 80% is excreted via the kidneys without undergoing any transformation.
The toxicity of chlorophenols depends upon the degree of chlorination, the position of the chlorine atoms and the purity of the sample. Chlorophenols have an irritating effect on the eyes and on the respiratory tract. Toxic doses of chlorophenols cause convulsions, shortness of breath, coma and finally death. After repeated administration, toxic doses may result in damage to the inner organs (primarily liver) and the bone marrow.
Pentachlorophenol has a toxic effect on embryos in animal experiments (lethal at higher concentrations). Technical PCP may possibly be carcinogenic not least due to contamination. Mutagenic potential can not be excluded.
ENVIRONMENTAL BEHAVIOUR
Water:
In the aquatic environment, chlorophenols may be dissolved in
free or complexed form or adsorbed on suspended matter. Removal
is mainly by way of biodegradation which is rapid when adapted
microorganisms are already present. However, PCP is biodegraded
much more difficultly than other chlorophenols. Chlorophenols are
also removed from water by photodecomposition and volatilisation.
Finally, adsorption of chlorophenols on suspended matter plays a
role in the amount of chlorophenols in water: light chlorophenols
are hardly fixed whereas PCP is fixed very strongly.
Air:
PCP ingresses into the atmosphere on account of its volatility.
Volatility increases considerably with increasing temperature,
but is likewise dependent on possible additives and e.g. the
nature of the treated wood. Burning wood treated with PCP
liberates polychlorinated dibenzodioxins and -furans (PCDD/F).
Soil:
The persistence of chlorophenols in soil depends on their
adsorption-desorption characteristics. Only the adsorption of PCP
has been studied in depth. It is fixed very strongly on soil
particles and not easily washed off by rain. Apart from
adsorption and desorption, rapid seepage paths can play an
important role in the transportation of PCP in soil. Once it
reaches the groundwater, it is doubtful whether PCP is degraded.
Since 1984 there has been a ban in Germany on the storage of
waste products from the manufacture of PCP on open dumps to avoid
the infiltration of PCP-contaminated seepage water.
Degradation, decomposition products, half-life:
Free PCP or PCP dissolved in water is photomineralised within
a few days when exposed to sunlight (even more so with adsorption
on solids). There is no such degradation if PCP has reached lower
soil levels or the groundwater. The degradation in water is
always dependent on the pH and the temperature. It is subject to
pronounced fluctuations (example: half-life at pH 5.1 = 328 h, at
pH 6 = 3,120 h (at 30°C in both cases)). Although PCP may be
degraded by microorganisms under certain conditions, the
substance is to be classed as scarcely biodegradable. Quinone
forms in the course of degradation and the process may involve
complete mineralisation.
Food chain:
Bioaccumulation in aquatic ecosystems does not only appear to be
extremely type-specific, but also dependent to a large extent on
the biotope as well as the duration and the intensity of
exposure. Excretion is likewise type/organ-specific with
half-lives ranging between 7 hours and 7 days. There are
contradictory findings as to whether PCP is absorbed directly
from the water by fish and other aquatic organisms or whether the
food chain is involved. Plants may accumulate PCP stored in the
soil over the course of several vegetation periods.
ENVIRONMENTAL STANDARDS
| Medium/acceptor | Sector | Country/organ. | Status |
Value | Cat. | Remarks | Source |
| Water: | Drinkw | D | L |
0.1 µg/l | acc. DVGW, 1988 | ||
| Drinkw | EC | L |
0.1 µg/l | acc. EC, 1980 | |||
| Groundw | D(HH) | G |
0.3 µg/l | Individual substance1) | acc. LAU-BW, 1989 | ||
| Groundw | D(HH) | G |
1.5 µg/l | Individual substance2) | acc. LAU-BW, 1989 | ||
| Groundw | D(HH) | G |
0.5 µg/l | Substance group1) | acc. LAU-BW, 1989 | ||
| Groundw | D(HH) | G |
2 µg/l | Substance group2) | acc. LAU-BW, 1989 | ||
| Groundw | NL | G |
0.25 µg/l | Monochlorophenol (sum) Reference |
acc. TERRA TECH 6/94 | ||
| Groundw | NL | L |
100 µg/l | Monochlorophenol (sum) Intervention |
acc. TERRA TECH 6/94 | ||
| Groundw | NL | G |
0.08 µg/l | Dichlorophenol (sum) Reference |
acc. TERRA TECH 6/94 | ||
| Groundw | NL | L |
30 µg/l | Dichlorophenol (sum) Intervention |
acc. TERRA TECH 6/94 | ||
| Groundw | NL | G |
0.025 µg/l | Trichlorophenol (sum) Reference |
acc. TERRA TECH 6/94 | ||
| Groundw | NL | L |
10 µg/l | Trichlorophenol (sum) Intervention |
acc. TERRA TECH 6/94 | ||
| Groundw | NL | G |
0.01 µg/l | Tetrachlorophenol (sum) Reference |
acc. TERRA TECH 6/94 | ||
| Groundw | NL | L |
10 µg/l | Tetrachlorophenol (sum) Intervention |
acc. TERRA TECH 6/94 | ||
| Groundw | NL | G |
0.02 µg/l | Pentachlorophenol (sum) Reference |
acc. TERRA TECH 6/94 | ||
| Groundw | NL | L |
3 µg/l | Pentachlorophenol (sum) Intervention |
acc. TERRA TECH 6/94 | ||
| Surface | D | G |
1 µg/l | Individual substance3) | acc. LAU-BW5), 1989 | ||
| Surface | D | G |
5 µg/l | Individual substance3) | acc. LAU-BW6), 1989 | ||
| Surface | D | G |
2 µg/l | Substance group4) | acc. LAU-BW5), 1989 | ||
| Surface | D | G |
10 µg/l | Substance group4) | acc. LAU-BW6), 1989 | ||
| Soil: | NL | L |
10 mg/kg AD | Substance group, Intervention | acc. TERRA TECH 6/94 | ||
| NL | L |
5 mg/kg AD | Pentachlorophenol, Intervention |
acc. TERRA TECH 6/94 | |||
| Air: | Workp | D | L |
0.5 mg/m3 | MAK | acc. DFG, 1989 | |
| Workp | SU | (L) |
0.1 mg/m3 | acc. DVGW, 1988 | |||
| Workp | USA | (L) |
0.5 mg/m3 | TWA | acc. DVGW, 1988 |
Notes:
1) The groundwater quality should be investigated in depth
2) Rehabilitation measures should be taken
3) For drinking water treatment using natural methods
4) For drinking water treatment using chemical and physical methods
5) Closer investigation necessary
6) Rehabilitation measures necessary
The use of all chlorophenols have been banned in Sweden since 1978.
Assessment/comments
Chlorophenols should be avoided where at all possible on account of the high toxicity level for aquatic organisms in some cases. The chlorination of drinking water to sterilise river water is problematic since this can lead to the formation of chlorophenols with penetrating odour and taste. Technical PCP contains impurities of other chlorinated phenols and aromatic substances as well as traces of polychlorinated dibenzo-p-dioxins and -furans (PCDD/F); it is thus one of the major sources of the ingress of these substances into the environment. Part of the toxicity of PCP can be attributed to such impurities.
Refer also to information sheets for 'phenols'.