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Substance Flow Analysis of Resorcinol

4 Exposure of humans and the environment

4.1 Resorcinol as a chemical intermediate
4.2 Resorcinol in wood glue
4.3 Resorcinol in rubber adhesives
4.4 Resorcinol in hair dye products
   4.4.1 Human exposure from use of hair dye products
4.5 Resorcinol in pharmaceuticals
4.6 Consumption as trace element and Unintended uses as contaminant
4.7 Summary and discussion
   4.7.1 Emission estimates
   4.7.2 Waste estimates

In this chapter, the information obtained from statistical sources and industrial surveys is used to estimate the environmental exposure and – where relevant – also human exposure.

The environmental exposure is estimated in the form of emissions to air, water and soil from processes taking place in Denmark. This is done by using the calculation procedures and default values from the EU Technical Guidance Document for risk assessment (TGD). Human exposure from the use of hair dye products containing resorcinol is also estimated by using the procedures of the TGD. Finally, generation of waste with active resorcinol is estimated by using information from the users of resorcinol and resorcinol-containing products.

The estimates are presented for each industrial and private application, allowing an identification of the most important leaks to the environment.

4.1 Resorcinol as a chemical intermediate

In 2002, two tons of resorcinol was imported to Denmark for use in chemical synthesis. It has not been possible to obtain information on the processes applied or the products being manufactured from resorcinol. Another 751 kg were imported for use in manufacturing of glue adhesives.

Based on the methodology described in the Technical Guidance Document (TGD) for EU risk assessment, the emissions to air, wastewater and soil can be estimated, the main assumption being that the total of 2,751 kg is used as an intermediate in chemical synthesis.

For chemicals with a vapour pressure < 1 Pa, the TGD assumes that there will be no emissions to air.

When processing less than 1,000 tons per year, the fraction being released to wastewater is assumed to be 0.02, corresponding to 55 kg.

The fraction emitted to soil is assumed to be 0.0001 of the processed amount, corresponding to 0.028 kg.

There is no information on generation of waste in chemical synthesis.

4.2 Resorcinol in wood glue

The EU TGD does not contain information relating to manufacturing of wood products. In order to give an estimate of the emissions, it has therefore been assumed that the emission pattern is similar to that of curing agents used for thermosetting resins in the polymer industry.

For this use category, a fraction of 0.075 (7.5%) is estimated to be released to air, corresponding to between 254 kg and 872 kg when low/high estimates from the industrial survey are used. The worst case estimate, assuming that 14 tons is used as wood glue, is that 1050 kg are emitted to air.

A fraction of 0.00005 is assumed to be realeased with wastewater, corresponding to between 0.17 kg and 0.58 kg when low/high estimates from the industrial survey are used. The worst case estimate, assuming that 14 tons is used as wood glue, is that 0.7 kg is emitted to water.

A fraction of 0.00001 is assumed to be released to soil, corresponding to between 0.03 kg and 0.12 kg when low/high estimates from the industrial survey are used. The worst case estimate, assuming that 14 tons is used as wood glue, is 0.14 kg being emitted to soil.

In the production of laminated wood/plywood small amounts of glue containing resorcinol will inevitably be disposed. A small survey among laminated wood manufacturers found that specialised recirculation processes minimise the glue waste. In practice, there will only be spills from the inside of the glue containers. This is estimated to be 1% of the total amount (34-116 kg/worst estimate 140 kg) and is assumed to be disposed of as chemical waste to Kommunekemi.

4.3 Resorcinol in rubber adhesives

There is no emission estimates for rubber production in the EU TGD. Production of thermosetting resins is assumed to cover the processes, and based on the EU TGD, the following fractions are assumed to be released to air, water and soil, respectively:

A fraction of 0.075 (7.5%) is estimated to be released to air, corresponding to between 19.5 kg (survey estimate) and 292.5 kg (statistical estimate; worst case).

A fraction of 0.00005 is assumed to be estimated with wastewater, corresponding to between 0.01 (survey) and 0.2 kg (worst case).

A fraction of 0.00001 is assumed to be released to soil, corresponding to between 0.003 kg (survey) and 0.04 kg (worst case).

The empty barrels with resorcinol adhesive will be disposed as chemical waste to Kommunekemi. It is estimated that 5% of the resorcinol is remaining in the barrels, corresponding to 13 kg and 195 kg, respectively, for survey and worst case estimate.

4.4 Resorcinol in hair dye products

Resorcinol in hair dye products is not included in the statistical information. The estimates below are therefore low/high estimates from the industrial survey.

In the EU TGD the default emission fraction values for cosmetics used privately are:

• Air: 0
• Waste water: 0.8, corresponding to 800-1360 kg/year)
• Soil: 0.001, corresponding to 1.0-1.7 kg/year

The default value for emissions via wastewater (80%) to municipal water treatment plants is assumed to be a fair estimate. Interviews with hairdressers reveals that any surplus colour will be rinsed from the mixing bowl and emitted to the waste water.

The major uncertainty is probably the amount of active resorcinol in the emissions. According to Rastogi et al, 2003, the compounds in hair dyes react very quickly, and it is possible that almost all resorcinol will be reacted before being emitted. The above estimate is therefore assumed to be conservative.

It is assumed that 5% of the active substances remain in the tubes in which they were delivered to the hairdresser. This corresponds to between 50 and 85 kg for low and high estimates, respectively.

4.4.1 Human exposure from use of hair dye products

In theory, hairdressers have the largest potential for exposure to resorcinol in hair dye products. However, plastic or rubber gloves are always used in the hair dyeing process, and the dermal exposure is therefore assumed to be insignificant. Based on the default values in the EU TGD, this is also the case for airborne emissions, but it is mentioned that there is a potential for aerosol formation during the dyeing process. This has not been quantified.

People having their hair dyed with products containing resorcinol are exposed to resorcinol through direct skin contact. According to the rules governing cosmetic products in the European Union (European Commission, 1999), the exposure shall be calculated using the assumption that the entire amount applied to the skin is absorbed. Furthermore, a partition coefficient between skin and hair of 0.9 has to be considered, i.e. that 10% of the total amount of hair dye is applied to the scalp.

If it is assumed that the product contains 1% of resorcinol, and 60 grams (cm³) of hair dye is used in each dyeing process, the potential uptake can then be calculated to 60 mg per session. With a body weight of 60 kg, the potential uptake per kg body weight per hair dyeing session is 1 mg. It is remarked that the Cosmetics Directive permits a content of up to 5% resorcinol in hair dye products, and the potential uptake is in this case 5 g/kg body weight. However, the maximum content of resorcinol found in hair dye products on the Danish market in 2002 was 1.13%.

4.5 Resorcinol in pharmaceuticals

The full amount of resorcinol applied to the human eye will be absorbed in the body, while the use in pharmaceuticals is assumed not to cause significant emissions to air, water or soil. It is remarked that there is a risk of resorcinol remaining after finishing of the treatment may be poured into the drain and accordingly be emitted with waste water.

4.6 Consumption as trace element and Unintended uses as contaminant

Resorcinol is known to be present in smoke from wood and cigarettes. Human exposure has been estimated by ASH in New Zealand (Action on Smoking and Health, www.ash.org.nz). A typical non-smoking service employee will inhale 123 ng of resorcinol in an 8 hour shift in a 300 m² area where there are 10 smokers smoking two cigarettes per hour and standard ventilation rates are applied.

No further efforts have been devoted to calculate the total emissions of resorcinol from tobacco and wood smoke in Denmark.

Resorcinol may be released to the environment in waste effluents associated with coal gasification and conversion, coal-tar production, and shale oil processing. The concentration of resorcinol in condensate water from a coal gasification plant in North Dakota, USA, ranged from not detected to 60 ppm over a two-year period. Resorcinol in concentrations of 1000 ppm was detected in wastewater from a synthetic coal conversion process. Information on such occurrences in Denmark has not been found.

4.7 Summary and discussion

4.7.1 Emission estimates

As described in the previous chapter there are some inconsistencies between the statistical information and the information obtained by surveys. In order to give the best overview it has been chosen to present the information in two ways, i.e. a worst-case estimate and a “survey” estimate. In the worst case estimate, the amounts being reported in statistical sources is supplemented with the information from the surveys, e.g. regarding the use in hair dye products.

The survey estimate presents the estimates of environmental exposures, based alone on survey information. In the survey, ranges are given for wood glue and hair dyes. Accordingly, a low/high estimate has been established and reported in the previous sections. In the presentation below, the low estimate from the survey is combined with the high (worst case) estimate from the combined statistical and survey information. Together, they are assumed to give a realistic figure for the range of emissions of resorcinol to different compartments of the environment.

Table 4.1. Minimum and maximum estimates(in kilos) of emission of resorcinol in Denmark.

4.7.2 Waste estimates

There is very little information available on generation of waste containing resorcinol. The information is summarized in Table 4.2 below.

Table 4.2. Generation of waste containing resorcinol in Denmark

1 Chemial waste disposed at Kommunekemi
2 Household waste, disposed by incineration

Besides the amounts generated during production and processing of resorcinol, estimates have been established regarding the amounts of resorcinol in final products. Eventually, all wood products with resorcinol are assumed to be incinerated with energy recovery. Rubber products are assumed to be incinerated or landfilled, depending of the disposal route for the products they are part of.

The figures are presented in appendices, the reason being that the resorcinol in the products are strongly bonded in a matrix, if not fully reacted. The potential for release of resorcinol to the environment via waste is therefore very small.

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Version 1.0 November 2004, © Danish Environmental Protection Agency