|Substance Group: TAED |
1. Executive Summary
TAED (tetraacetylethylenediamine) is a bleaching activator which is mainly used in detergents and additives for laundry washing and dishwashing. Typical concentrations of TAED range between 1.4% and 13% in these products. The amount of TAED which is used in household cleaning products in Europe was estimated to be 61,000 t in 2001. After starting the washing process, TAED is completely dissolved within minutes in the wash liquor and undergoes perhydrolysis in the presence of persalts such as perborate or percarbonate via triacetylethylenediamine (TriAED) to diacetylethylenediamine (DAED). A recent kinetic study of the perhydrolysis under conditions of the washing process (pH 10) has shown that TAED is converted >99% to DAED even at low temperature (23 degree C). In this risk assessment report the parent compound TAED as well as the final degradation product DAED were assessed. TriAED was not considered as no significant concentrations arise during the perhydrolysis process.
For the Environmental Assessment it was assumed that after the washing process has been finished 99% of DAED and 1% of TAED is discharged into the sewer. A full environmental risk assessment was carried out for TAED and DAED with the modelling program EUSES using different scenarios. TAED and DAED which have high water solubility are readily eliminated in sewage treatment plants (> 97%) and degradation in river water is rapid with half-lives of about 9d. Although TAED and DAED do not sorb strongly to dissolved and suspended matter some emissions to agricultural soil may occur via application of sewage sludge. Emissions to air can be neglected. Due to the low octanol-water partitioning coefficient of TAED and DAED bioconcentration and bioaccumulation will not occur. For the same reasons secondary poisoning and indirect exposure of humans via environment are unlikely. TAED and DAED show low acute aquatic ecotoxicity. Sediment and soil ecotoxicity data are not available but estimations were carried out using the equilibrium partitioning method. From these data and the estimates PNECs for the different environmental compartments were derived. The Risk Characterisations for water, sediment, soil and sewage treatment plant based on the estimated PECs and PNECs show that the risk quotients for all scenarios were below 1 (acceptable risk).
TAED is of very low toxicity by all exposure routes examined. Up to 2 g/kg BW there is no acute toxicity. TAED is practically non-irritating to skin and eyes and there is no evidence of a sensitizing potential by skin contact. The only effect after repeated oral and dermal dosing was reversible centrilobular hypertrophy in the liver at high doses due to the induction of metabolizing enzymes. In a 90-day whole body inhalation study no adverse effects in the rat lung, respiratory tract or nasal mucosa were observed. Biokinetic data showed that TAED is rapidly absorbed from the rat intestine and largely metabolized via diacetylation to TriAED and DAED which are excreted in the urine. Skin penetration studies indicated, that 0.13%-4.3% of pure TAED or TAED present in solutions of detergent bases can penetrate rat skin depending on contact time. TAED was not genotoxic and not teratogenic. Chronic toxicity, carcinogenicity, fertility and late stages of developmental toxicity (from birth to sexual maturity of offspring) have not been addressed. However, based on the chemical structure and the available toxicity and kinetic data it can be expected that TAED will cause no concern with respect to these endpoints. Based on above data, the No Observed Adverse Effect Level of 90 mg/kg BW/d was deduced to assess systemic TAED exposure. There are only a few toxicity data available on DAED and they all indicate very low toxicity. DAED was not acute toxic at a dose of 2 g/kg BW when given orally and was non-mutagenic and non-sensitizing. It was rapidly absorbed from the gastroinestinal tract and excreted via urine. The No Observed Effect Level of 5700 mg/kg BW/d has been reported in a 90-day rat feeding study. For all other endpoints, data on TAED can be used as bridging data. The presence of TAED in many commonly used household detergents gives rise to a variety of possible consumer contact scenarios including direct and indirect skin contact, inhalation, and oral ingestion. The total systemic exposure resulting from these scenarios was estimated to be 0.013 µg TAED and 0.089 µg DAED/kg BW/day. In conjunction with the NO(A)ELs for systemic exposure (90 mg TAED/kg BW/d and 5700 mg DAED/kg BW/d) the extremely high Margin of Exposures of 7,030,000 and 64,100,000 were determined for TAED and DAED, respectively, indicating no risk for human health. On the basis of the toxicological data skin sensitization, accidental exposure of skin or eyes as well as accidental ingestion are of low concern. It can be concluded that TAED contained in consumer washing and dish washing products as well as the amount of DAED formed during the washing process do not cause concern to human health.