Survey of azo-colorants in Denmark

Methodology

Mass flow analysis

The mass flow analysis paradigm

The mass flow analysis of the present survey on azo colorants is based on an evaluation of the individual parameters in the equation below:

Input + Production = Output + Accumulation

The individual parameters of the balance are defined as follows:

	Input data consist of data on imports of azo colorants and products containing the colorants.
	Production encompasses azo colorants produced in Denmark and products containing colorants.
	Output data are re-exports of azo colorants, exports of colorants in products, disposal of waste (azo colorants and products) and emissions to the environment (water, soil and air).
	Accumulation refers in the present survey to stock building. Accumulation is assumed to be zero.

Principally the equation always balances, as matter cannot be formed nor destroyed.

The Danish EPA has made a paradigm for mass flow analysis (Miljøsty- relsen, 1993) which focuses on analysis of compounds or products. The present survey is based on this particular paradigm, which has also provided the basis for definition of the scope of the survey.

However, conducting a survey like the present on azo colorants in Denmark implies that several thousand compounds are of potential interest, due to the fact that the azo colorant consists of more than 3,000 compounds and that at least 120 compounds, which are restricted in some countries, are in focus. The survey is further complicated because most statistical records describe the compounds on an aggregated basis.

Therefore, the method of the mass flow analysis has been adjusted to match the available data.

Statistics

It should be noted that no available statistics or database records specifically address the comsumption and applications of azo colorants in Denmark.

Generally, statistics of foreign trade and statistics on total supply are of limited value for the present survey. Single groups, like the azo colorants, are only registered in connection with trade in colorants (dyes and pigments), whereas their presence as ingredients in other products are difficult to trace in the statistics, exclusively.

Method of the present mass flow analysis

Input and output of colorants are estimated on the basis of studies of the application in products. Therefore, based on studies of specific uses and product groups, the input may be calculated. Knowing the input of azo colorants to a specific product group (application) and how it is used, the fate of the azo colorant may be estimated.

Numbers

Results from calculations are shown with 2-3 digits in order to facilitate control.

The parameters of the mass balance analysis

Each parameter of the mass balance analysis is described below with special attention to the sources of information and data input. Furthermore, the general assumptions and background for the estimates in chapter 4 are presented and discussed.

Input

Input data have been gathered from three main sources:

The statistics on supply and foreign trade have been used when describing individual product groups and country of origin.

Statistics on total supply and foreign trade have been used extensively. Both references provide data in terms of weight and sales values for a detailed list of materials and products according to the customs tariff. The statistics of foreign trade specify country of origin and destination, and the latter includes the Danish production. None of these references specify azo colorants.

Certain products with dangerous properties must be registered in the Product Register. Here information on use and quantities of dyes and pigments is registered, and if they are mixed with chemicals which have to be registered.

It is not possible to conduct a broad survey of azo colorants as such in the Product Register. Therefore, the first survey was carried out on 200 specific azo colorants, which according to the literature are commonly used. Later a survey was conducted on approximately 100 azo colorants which are restricted in Germany and the Netherlands.

The survey on the data from the Product Register only provided in-formation on whether a colorant is in use or not. The data on the volume in use are doubtful due to the structure of the database, as pigments/dyes in e.g. paints are normally registered in bulks with a fixed percentage of all goods, even though some of the paint may not be coloured at all. Consequently, data from the Product Register on quantities of colorants are not used directly in this survey.

In some cases the colorants are only present in a part of a product (e.g. colorants in shoes are only to be found in leather and not all shoes consist of leather). In these cases the product group (shoes) is divided into more homogenous groups (clogs, sandals), where the relative share of the colour containing the element (leather) can be estimated more precisely. The volumes in tonnes of the product groups are obtained from the statistics. This method is used to estimate colorants used in leather, textiles and printed matter.

Output

Output data have been described and estimated by using different sources:

	Reports from the Danish EPA and articles are the main references. In some cases data from these sources are considerably older than those in the above mentioned statistics and thus adding uncertainty to the analysis.
	Experts from companies, organisations etc. have supplied with in-sight, comments and estimates in cases where objective evidence is missing (e.g. on manufacturing of coloured plastics):

	Federation of Danish Textile & Clothing
	Association of Graphic Industries in Denmark
	The Danish Plastics Federation
	The Danish Paintmakers Association
	The Danish Paintmakers Association
	Makrodan, Kunsstofkemi, Wilson Color, Berendsen Miljø, Brdr. Hartmann, Store Dalum
	Institute for Product Development
	Danish Technological Institute - Textile
	The Graphic Arts Institute of Denmark

	Through their trade organisation, the above manufacturers of paints and varnishes have supplied us with information on their use of specific colorants.
	Foreign organisations and companies have supplied with data, articles and references on colorants:
	ETAD (Ecological and Toxicological Association of Dyes and Organic Pigments Manufacturers, Switzerland)
	European Chemicals Bureau, ISPRA, Italy
	RPA (Risk and Policy Analysis Limited, Great Britain)
	Bundesministerium für Jugend, Familie und Umwelt, Austria

Disposal and emissions

In the output analysis of disposal and emissions, some general assumptions have been made:

Predominantly disposal takes place through disposal of waste to landfills and incineration.

The relative distribution between landfills, incineration and recycling of household waste is assumed to be valid for industrial waste too, as precise data are unavailable. Due to the conditions in the specific uses, the distribution is modified as follows:

Paper: 42% of all types of paper products and waste are recycled, thus the remaining 58% are distributed between landfills and incineration.

Plastic, textile, leather and paint: As there is little or no recycling, the recycling rate is assumed to be approximately 0. Thus, the disposal is distributed between landfills and incineration.

The distribution is shown in Table 2.1.

The analysis only evaluates the amount of azo colorants deposited and not the amount of the decomposition products.

Emissions

Emissions comprise of: Emission to waste water, atmosphere and soil.

Emissions to waste water are calculated in total amounts before waste water treatment.

Emissions to the atmosphere during processing in the use phase are estimated to be zero.

Emissions of azo colorants to the atmosphere during incineration of waste are assumed to be negligible, as the azo colorants in question being organic molecules are decomposed by incineration at 800-1,200 ^o C.

Emissions to soil are generally estimated to be zero, except from disposal of de-inking sludge and application of sludge to agricultural soil (see chapter 4, section 4.5).

Share of azo colorants

No statistics exist on the share of azo dyes in relation to the total amount of dyes, but several references agree that azo dyes represent the majority: 70% (Brown & Anliker, 1988), 60 to 80% (RPA, 1997), 60 to 70 % (ETAD, 1997), and "the majority" (Eitel, 1988). If nothing else is stated, azo dyes are assumed to represent 70 % of all dyes.

Likewise 70% of the pigments are assumed to be azo colorants, if nothing else is stated. This is probably an overestimate, because the inorganic whitening pigment TiO₂ is extensively used in the graphic trade and in the manufacture of paints and lacquers.

Evaluation of the method

Critique

The applied method is one-dimensional, because the output is more or less estimated on the basis of the input. Alternative ways for estimating the parameters of the balance have been established for validation:

The data used have been cross-checked whenever it has been possible.

The method implies that there are no stocks (accumulation = 0) which presumably is rarely true. Accumulation is only of interest if the stocks are large or vary a lot from year to year.

Accumulation of colorants in production of materials and finished goods may be estimated to be approximately 0, as companies avoid binding capital in stocks. Accumulation of consumer products takes place to some extent, but it is assumed that stock piling is limited.

Accumulation of non-degraded colorants may take place in landfills and in soils, where sludge from waste water treatment is deposited. The mass flow analysis does not evaluate this process.

Validation

The results based on the above mentioned method are very dependent on the quality of the assumptions made. Apart from cross-checking whenever possible, the steering committee and independent experts have been consulted.

Technical aspects of azo colorants

The information on the technical aspects of azo colorants is mainly obtained from handbooks like Ullmann and Kirk-Orthmer, if no other author is stated.

Human toxicity assessment

Assessment of the human toxicity of azo colorants has been based on information from databases, namely CISDOC, ECDIN, NIOSHIC and HSDB (cf. references). Detailed information was provided by the published literature, including monographs published by IARC, the International Agency for Research on Cancer.

Due to the epidemiological evidence of carcinogenicity of azo dyes, extensive toxicological investigations were mainly related to carcinogeni- city and the mechanism behind. Some information from the clinic was available regarding some groups of azo colorants and skin sensitisation. To the remaining toxicological end-points, limited attention was given, because they are predominantly related obsolete colorants of today.

On this background the toxicity profile in chapters 5 and 6 reflects the relevant information available on azo colorants and therefore does not fulfil the whole spectrum of toxicological end-points.

Environmental assessment

Assessment of environmental fate and ecotoxicity of azo colorants are based on information from the databases ECDIN, AQUIRE, IUCLID and HSDB. Detailed information was provided by the published literature, including monographs published by MITI and NPIRI.

The assessment of persistence, accumulation and potential bioaccumulation as well as the ecotoxicity of azo colorants are based on the internationally accepted technical guidance documents of the EU Commission (TGD 1996).

Furthermore, the general lack of data on the above mentioned parameters implied that a serie of QSARs (Quantitative Structure Activity Relationship) had to be performed in order to obtain an estimated indication of, among other things, the partition coefficient and ecotoxicity. The applied QSAR methods are based on EPIWIN and TGD (1996).

The predicted environmental concentration (PEC) is estimated, based on a standard model of municipal sewage treatment plants accepted by the EU (TGD 1996). Predicted no effect concentration (PNEC) is estimated according to the OECD guidelines. Due to the limited availability of monitoring data, i.e. when no data from Denmark exist, worst case scenarios are presented.

Due to the epidemiological evidence of carcinogenicity of azo dyes in humans, studies have been performed to establish degradation in the environment and to a less extent the bioconcentration and the ecotoxicity of the dyes. The azo pigments are very poorly studied. Therefore, the survey is turned towards dyes. In general, no data on long-term exposure to azo colorants have been obtained.

Subsequently, the toxicity profile provided in chapters 5 and 6 reflects susceptibility and toxicity in short term studies, and therefore the effects of long-term exposure remain speculative.