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Substance Flow Analysis of Resorcinol

5 Environmental and health hazards of resorcinol

5.1 Toxicity and ecotoxicity of resorcinol
   5.1.1 Classification and labelling
   5.1.2 Human toxicity
   5.1.3 Animal toxicity
   5.1.4 Carcinogenicity
   5.1.5 Endocrine disruption
   5.1.6 Environmental fate and exposure
   5.1.7 Ecotoxicity

5.1 Toxicity and ecotoxicity of resorcinol

5.1.1 Classification and labelling

Resorcinol is classified by the EU and the Danish authorities as harmful (Xn), irritant (Xi) and dangerous for the environment (N). The following risk and safety phrases apply:

• R22 (Harmful if swallowed)
• R36/38 (Irritating to eyes and skin)
• R50 (Very toxic to aquatic organisms)
• S2 (Keep out of the reach of children)
• S26 (In case of contact with eyes, rinse immediately with plenty of water and seek medical advice)
• S61 (Avoid release to the environment. Refer to special instructions/Safety data sheets)

5.1.2 Human toxicity

Resorcinol is harmful if swallowed, inhaled or absorbed through skin and causes eye and skin irritation. The compound is irritating to mucous membranes and upper respiratory tract. Depending on the intensity and duration of exposure, effects may vary from mild irritation to severe burns.

Cutaneous application of solutions or salves containing from 3 to 25% of the compound may result in local hyperemia, itching, dermatitis, corrosion, and the loss of superficial layers of the skin.

The substance may cause effects on the blood, resulting in formation of methaemoglobin. The effects may be delayed and medical observation is indicated. (HSDB, 2003). Several cases of fatal poisoning following skin contact with resorcinol have been reported (Jensen, 2001).

Resorcinol is regarded as goitrogenic, causing hypo-thyroidism following persistent exposure, e.g. through intake of drinking water polluted with resorcinol from coal gasification and shale oil production, or through use as topical ointment on skin lesions. It is this effect that has been shown by epidemiological studies and used as evidence for listing resorcinol as a category 1 substance (substance of high concern) in the EU list of substances for further evaluation of their role in endocrine disruption (BKH, 2000).

5.1.3 Animal toxicity

Resorcinol is moderately toxic in animal tests. The following toxicity values have been reported (HSDB, 2003):

LD₅₀ (rat, oral): 301 mg/kg; 980 mg/kg
LD₅₀ (mouse, ip.): 215 mg/kg
LD₅₀ (rabbit, dermal): 3.36 g/kg

Lethal oral doses have been reported to approx. 0.37 g/kg for rats and guinea pigs, and approx. 0.75 g/kg for rabbits.

In an inhalation toxicity test, aerosol (resorcinol-water) concentrations as high as 7800 mg/m³ for a 1-hour period and 2800 mg/m³ for an 8-hour period caused no deaths or lesions attributable to inhalation of the aerosol at gross autopsy.

Application of 0.1 g of resorcinol into the eyes of rabbits caused discomfort, conjunctivitis and corneal ulcerations, which were not reversible. Application of 0.5 g of resorcinol moistened with saline to intact or abraded skin of rabbits for up to 24 hours caused reactions varying from no irritation to moderate irritation of the intact skin, and from no irritation to necrosis of the abraded skin.

5.1.4 Carcinogenicity

IARC (1999) has evaluated that no epidemiological data relevant to the carcinogenicity of resorcinol were available. There is inadequate evidence in experimental animals for the carcinogenicity of the compound. The overall evaluation from IARC is that resorcinol is not classifiable as to its carcinogenicity to humans and the compound is placed in Group 3.

5.1.5 Endocrine disruption

Resorcinol has been assessed at an expert panel meeting as a step in the procedure towards the establishment of a priority list of substances for further evaluation of their role in endocrine disruption (BKH, 2000).

The expert panel concluded that human health relevant endocrine disruption data were of category 1, i.e. that at least one study providing evidence on endocrine disruption in an intact organism was identified. In practice, a study documenting changes in goitrogenic activity in workers (decreased T4/T3 metabolism) was used as evidence. Wildlife endocrine disruption data were evaluated as category 3, i.e. there was no scientific basis for inclusion in the list or no data.

Due to the potential for human exposure through use as a pharmaceutical or cosmetic on skin and by wood or cigarette smoke inhalation, resorcinol is prioritised by the expert panel as being af substance of high concern.

5.1.6 Environmental fate and exposure

Resorcinol is readily biodegradable and do not bioaccumulate.

If released to air, the vapour pressure (4.9 * 10^-4 mm Hg at 25°C) indicates that resorcinol will exist solely as a vapour in the ambient atmosphere. Vapour-phase resorcinol will be degraded in the atmosphere by reaction with photochemically produced hydroxyl radicals, the half-life for this reaction is estimated to be 1.9 hours. If released to soil, resorcinol is expected to have a high mobility based upon an estimated coefficient of adsorption for substance in soil (Koc) of 65.

Biodegradation is expected to an important environmental fate process for resorcinol. Complete degradation occurred in 8 days as determined by a 100% UV absorbancy loss. The half-life of resorcinol in an aerobic screening test ranged from 0.16 to 0.24 days using activated sludge.

An estimated bioconcentration factor (BCF) of 2 suggests that the potential for bioaccumulation in aquatic organisms is low. Hydrolysis is not expected to an important environmental fate process due to a lack of hydrolysable functional groups.

5.1.7 Ecotoxicity

Resorcinol is toxic to aquatic organisms.

HSDB (2003) quotes a number of LC₅₀-values from K. Verschuerens “Handbook of environmental data of organic chemicals” from 1983. The conditions of the bioassys were not specified for any of the following values:

The AQUIRE database gives additional information for daphnia (AQUIRE, 2003):

LC₅₀, daphnia:     0.25-0.9 mg/l (96 h)

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Version 1.0 November 2004, © Danish Environmental Protection Agency