Ftalatos Dibutilftalato

Introduction: What are phthalates?

The source document for this Digest states:

Phthalates are widely used as plasticisers in a range of polymers (e.g., PVC) that are found in a wide range of consumer products including floor- and wall covering, furnishing, toys, car interior, clothing, hoses etc. Phthalates are also applied to paints and lacquers, adhesives and sealants, printing inks etc. The phthalates are not chemically bound in the polymers. Therefore, migration or emission of the phthalates from the product to water, air or other media in contact with the product is likely to occur. The emission of phthalates occurs in all life stages of a product (from production to disposal) and the phthalates are thereby widespread in the environment.

Five of the most widely used phthalates are di-(2-ethylhexyl) phthalate (DEHP), dibutyl phthalate (DBP), di-isononyl phthalate (DINP), di-isodecyl phthalate (DIDP) and benzyl butyl phthalate (BBP). These are the phthalates in focus in the present report.

Within the EU, specific programs on risk assessment for new and existing chemical substances, including the above-mentioned phthalates, are ongoing. A directive (EEC 1993a) provides the regulation on risk assessment of new notified chemical substances 1 and two Council regulations (EEC 1993b, EEC 1994) on risk assessment of existing substances.

The risk assessment process, in relation to both human health and the environment, entails a sequence of actions:

1) Effect assessment comprising a) hazard identification (identification of the adverse effects which a substance has, and b) dose (concentration) - response (effects) assessment (estimation of the relationship between dose, or level of exposure to a substance, and the incidence and severity of an effect.

2) Exposure assessment (estimation of the concentrations/doses to which human populations or environmental compartments are exposed).

3) Risk characterisation (estimation of the incidence and severity of the adverse effects likely to occur in a human population or environmental compartment due to actual or predicted exposure).

A Risk Assessment Report (EU-RAR) is prepared for each prioritised substance. The EU-RAR for DBP was published 18 March 2003 (http://ecb.jrc.it); however the final draft for decision on the conclusions by the EU Competent Authorities (DBP 2001) has been used in the present report. Regarding DEHP, DINP and DIDP, the EU-RARs have not yet been published and the final drafts for decision on the conclusions by the EU Competent Authorities have been used in the present report (DEHP, 2001; DINP, 2001, DIDP, 2001). For BBP, discussions are still ongoing in the EU Working Group and the draft report is not yet public available.

The exposure assessment and risk characterisation are carried out separately for three subgroups of the human population: workers, consumers, and man exposed indirectly via the environment.

Indirect exposure of humans via the environment may occur by consumption of food (fish, crops, meat and milk) and drinking water, inhalation of ambient air, and ingestion of soil. For existing substance, measured levels in various environmental compartments may be available; however , for new substances, usually no relevant measured data are available and concentrations of a substance in the environment must be estimated. The indirect exposure is estimated by the use of the European Union System for the Evaluation of Substances (EUSES) - a computer modeling program. EUSES estimates concentrations in food and the total daily intake of a substance based on predicted environmental concentrations for (surface) water, groundwater, soil, sediment and ambient air. The indirect exposure is principally assessed on two spatial scales: locally near a point source of the substance, and regionally using averaged concentrations over a larger area. It should be noted that a third spatial scale, the continental scale, is also assessed by EUSES; however, this it not included in the estimations of the indirect exposure. EUSES can specifically be used in the initial (or screening) and intermediate (or refined) stages of assessment. On the basis of the screening, it can be decided if more data need to be generated and if a more refined assessment is necessary. EUSES can also be applied for refined assessments by allowing the replacement of default values, estimated parameter values, or intermediate results by more accurately estimated values or by measured data. EUSES is not specifically designed for site-specific assessments (defaults represent a standard region in EU), but adjustment of parameters may allow for insight into specific local or regional situations.

The consumer, i.e. a member of the general public who may be of any age, either sex, and in any stage of health may be exposed to a new or existing substance by using consumer products. A consumer product is one, which can be purchased from retail outlets by members of the general public and may be the substance itself, or a preparation, or an article containing the substance. To assess the exposure to substances present in consumer products, information is needed on two sets of parameters: 1) contact parameters (where, how long and how often contact with the consumer occurs) and 2) concentration parameters (the concentration of as substance in a medium that might contact the body. Measured data on external exposure for specific scenarios may be available for a number of substances; however, most often such data are not available. A number of computerised models have been developed; no particular model is recommended above any other. Whenever possible measured or estimated values should be used for each of the numerical parameters in a given model, but when this is not possible default values may be derived from available data sources. Within the EU available consumer products are more or less the same and the consumer exposure assessments in the EU-RARs are likely also to represent more site-specific assessments and thus, are representative for Danish consumers as well.

Source & ©:  "Human exposure to selected phthalates in Denmark", Introduction (p.11-12)

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