Symposium 8

Environmental toxicity and health

Fresenius J Anal Chem (1992) 343:29 - © Springer-Verlag 1992

The complexicity of ecosystems

N.N.

Manuscript not received

Fresenius J Anal Chem (1992) 343 :29 -30 - © Springer-Verlag 1992

Criteria to classify ecotoxic chemicals

G. Welter

Umwelt-Bundesamt, Bismarckplatz 1, W-1000 Berlin 33, Federal Republic of Germany

Up to now according to the German chemicals' law there exists no definition for the classification of chemicals on the basis of environmental effects. Within the EEC, by the 12. Amendment of Directive 67/548/EEC, dated March 1, 1991, criteria for classification came into force [1]. As stated in the amendment, the primary objective of classifying substances "dangerous for the environment" is to alert the user to the hazards these sub- stances present to ecosystems. Although the present criteria largely refer to aquatic ecosystems, it is recognised that certain substances may simultaneously or alternatively affect other eco- systems whose constituents may range from soil microflora and microfauna to primates.

This problem is one aspect of the fundamental difference between health hazards and environmental hazards. The purpose of the assessment of health hazards is to protect in- dividuals of one single species, while the environmental assess- ment is intended to protect populations and communities of very different kinds and composed of a multitude of different species.

All systems for the classification are based on the same type of information reflecting the intrinsic properties of chemical substances with regard to toxicity, potential for bioaccumula- tion and (bio) degradability. Additional parameters for the ex- posure assessment, are the quantity produced/imported and pro- cessed, the pattern of use and the physio-chemical properties. Due to the problems involved in careful exposure estimation, an aquatic concentration of 10 gg/1 is taken as a realistic worst case assumption for the upper limit of the aquatic exposure. This value was derived from experience with industrial chemicals of high production volume [2].

For the aquatic environment the most important parameter for the classification is the aquatic toxicity. Due to the fact that for new chemicals in the beginning only acute toxicity data are available, the criteria are mainly based on these data. The same situation is present for the more than 100000 "existing chemicals", i.e. substances which were on the common market before September 18, 1991. For aquatic organisms, acute toxicity means 96 h LC 50 for fish, 48 h EC 50 for Daphinia (effect:.immobilisation) or 72 h IC for algae (effect is reduction of algal growth).

Following the EEC directive, substances shall be classified as "very toxic to aquatic organisms" in case of an acute aquatic

toxicity of lower than 1 mg/1 for the most sensitive species; ranges for "toxic" and "harmful" are 1 to 10 and 10 to 100 mg/1, respectively.

Provided the acute aquatic toxicity is not lower than 1 mg/1, the potential for bioaccumulation and the biodegradation is considered additionally in order to estimate the potential for long-term adverse effects on the aquatic environment; sub- stances are only classified if they are not "readily biodegrad- able" or exhibit an octanol/water partition coefficient of more than 3.

In a more elaborated model, results of the tests for inherent biodegradability are used additionally [3]. These data are rele- vant for estimating the elimination of chemicals during the passage through industrial waste water treatment plants. Also, if available, the chronic aquatic toxicity is taken into considera- tion. Besides the different effects, the exposure of a target group is an important fact in the hazard assessment of chemicals. The limits for classification in this system were only developed for chemicals with an annual production and/or processing volume of more than 1000 tons. Here, one can expect in most cases a relevant exposure. Only for few chemicals, like only internally processed intermediates, significant exposure can sometimes be excluded after case-by-case judgement of the available data.

The system described above is merely used for discrimina- tion into groups related to environmental hazard, i.e. chemicals of concern or of low concern. Another approach would be the ranking of chemicals according to their initially assessed environmental hazard [4-8] .

All models use similar parameters but different limits and combinations of parameters for the classification. An often used way for the ranking of chemicals consists of the allocation of numerical scores on the basis of their respective hazard potential and of sorting them according to the magnitude of a specific combination of scores. In the scientific literature and within national and international organisations, the discussion on the merits and the drawbacks of the different models is still ongoing at present.

References

1. Richtlinie der Kommission vom 1. M/irz 1991 zur zw61ften Anpassung an den technischen Fortschritt der Richtlinie 67/ 548/EWG des Rates zur Angleichung der Rechts- und Verwaltungsvorschriften fiir die Einstufung, Verpackung und Kennzeichnung gef~hrlicher Stoffe (91/325/EWG). Amts- blatt der Europfiischen Gemeinschaften, Nr. L 180/2 vom 8.7. 1991

2. ECETOC - Technical Report No. 29 "Concentration of Industrial Organic Chemicals Measured in the Environment;