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Phenol

DESIGNATIONS

CAS No.: 108-95-2
Registry name: Phenol
Chemical name: Phenol
Synonyms, Trade names: Carbolic acid, hydroxybenzene, monohydroxybenzene, oxybenzene, phenic acid, phenyl hydrate, phenyl hydroxide, phenyl acid
Chemical name (German): Phenol, Karbolsäure, Hydroxybenzol
Chemical names (French): Phénol, acide carbolique, acide phénique, benzénol, phénol ordinaire
Appearance: colourless/whitish red substance or colourless melt; sweetish odour

BASIC CHEMICAL AND PHYSICAL DATA

ORIGIN AND USE

Usage:
Phenol is used to make synthetic resins, dyes, pharmaceuticals, pesticides, synthetic tanning agents, perfumes, lubricating oils and solvents.

Origin/derivation:
In the phenols group, cresols and the parent compound itself are the most important compounds as well as thymol, naphthols, phenolphthalein, trichlorophenol and pentachlorophenol. Natural compounds such as pyrocatechol, guaiacol and their derivatives are not toxic. A well-known pyrocatechol derivative is adrenaline. Phenol naturally occurs in pine wood and pine needles, in the urine of herbivores (phenol sulphate) and in coal tar. Monohydric phenols provide numerous natural scents (e.g. vanillin, thymol, carvacrol, zingiverone (in ginger), salicylaldehyde). Amongst the synthetic multivalent phenols hexachlorophene is particularly toxic.

Phenol is obtained from the distillation of coal tar (according to RÖMPP, (1983) 1 t of coal gives approx.0.25 kg of phenol). Synthetic production has however become predominant and involves the decomposition of cumene hydroperoxide with acetone forming as by-product. Some use is still made of the preparation from benzene using benzene sulphonic acid or chlorobenzene.

Emissions are produced by the incomplete combustion of gasoline and coal tar, in the waste water from coking plants and as metabolites in the photolysis of benzene and chlorobenzene.

Production figures:

Toxicity

Toxicity data for various phenol compounds can be found in DFG, 1982, volume II: phenols.

Characteristic effects:

Humans/mammals: Vapours and liquids are toxic and easily absorbed through the skin. Once inhaled, vapours corrode the respiratory tract and the lungs. Severe burns result from the liquid coming into contact with skin and eyes (phenol is a powerful protoplasmic poison). Long-term exposure paralyzes the central nervous system and damages the kidneys and the lungs. Paralysis may cause death. Accompanying symptoms are headaches, tinnitus, dizziness, stomach and intestinal irritations, drowsiness, collapse, poisoning, loss of consciousness, irregular breathing, apnoea, heart failure and in some cases spasms. HORN (1989) classes phenol as having a teratogenic and carcinogenic effect. According to the Ames-test, phenol has no mutagenic potential.

Damage caused by oral intake is usually prevented by the alarming odour and taste (Refer also to "cresol" and "chlorophenol" information sheets)

Plants: Passive permeability impaired; growth inhibited.

ENVIRONMENTAL BEHAVIOUR

Water:
Phenol is heavier than water and sinks to the bottom. It dissolves slowly and continues to form toxic solutions even when diluted. Because of its considerable toxicity in water, phenol is listed in water hazard class 2 in Germany.

Air:
Vapours are heavier than air and form explosive mixtures when exposed to heat. The oxidation of phenol in air is accelerated by light or impurities with a catalytic effect.

Soil:
There is only limited accumulation because of the microbial degradation in the soil (aerobic or anaerobic). The accumulation level depends on the presence of clay minerals (great affinity with aluminium oxide).

Degradation, decomposition products:
The biological degradability of natural phenols is generally very good with the result that there is scarcely any accumulation in plants or animals. Aerobic bacterial degradation involves complete breakdown to carbon dioxide. Condensation to humic acids may be found in soil. The degradability of synthetic phenols is less pronounced as many phenols are toxic to microorganisms. Toxicity increases with the number of chlorine or nitrogen atoms in the phenols. "Pentachlorophenol" is thus the most toxic compound of the chlorophenol group and trinitrophenol (picric acid) is the most poisonous compound within the nitrophenol group.

There is roughly 90% degradation in surface water in approx. 7 days (standing water); the same rate is achieved in soil in roughly 1 day depending on microflora and concentration (RIPPEN, 1989); complete degradation in earthy suspensions takes more than two days.

Phenol metabolites can also be extremely toxic: Incomplete combustion of 2,4,5-trichlorophenol may cause the formation of TCDD (dioxin). Biodegradation generally produces acetic acid and CO₂ by way of pyrocatechol, o-quinone and dicarboxylic acids (RIPPEN, 1982).

Phenol is excreted from the organism with the urine after oxidation or conjugation with sulphuric or gluconic acid.

Food chain:
There is only little accumulation in foodstuffs. Smokers are at risk since cigarette smoke contains phenols. The presence of phenol in groundwater causes polluted drinking water which may not be used because of its evil taste.

ENVIRONMENTAL STANDARDS

Notes:

¹⁾ Assessment value for soil and groundwater contamination, A value = no impact
²⁾ Assessment value for soil and groundwater contamination, B value = further investigations necessary
³⁾ Assessment value for soil and groundwater contamination, C value = rehabilitation needed
⁴⁾ Impact limit up to which drinking water can be produced solely by natural methods
⁵⁾ Impact limit up to which drinking water can be produced using currently tried and tested chemical/physical methods
⁶⁾ "Swiss quality goal" used as basis for assessing surface water and drinking water supply
⁷⁾ Limit value for introduction of sewage into flowing water
⁸⁾ Guideline for requirements to be satisfied by sewage introduced into public sewage systems in Baden-Württemberg
⁹⁾ Areas in need of protection
¹⁰⁾ Areas in need of special protection
¹¹⁾ 0ther areas not in need of special protection

Comparison/reference values

Assessment/comments

There is urgent need for reduced emissions since synthetic phenols are more toxic than natural phenols. The risk of skin contact and inhalation when handling phenol needs particular attention.

(Refer also to "chlorophenols" and "cresols" information sheets).

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