The European detergent industry divides along environmental lines, with the major players being represented by the Association Internationale de Savonniers (AIS) and smaller manufacturers catering specifically for the "green" market by the Environmental Detergent Manufacturers Association (EDMA).
The study by the Danish Consumers Organisation showed that a product made by Ecover, the EDMA's leading light, was likely to be ten times less damaging to the aquatic environment than its closest rival.
The study used the Microtox test, a bioassay based on the response of photo-luminescent bacteria, to measure the relative toxicity of the products before and after biodegradation. Toxicity was measured as the number of dilutions necessary to give a zero toxicity rating using the test. The biodegradability of the products was compared using a standard method approved by the OECD.
The toxicity and biodegradability scores were combined to give an overall score for environmental impact. This was calculated by multiplying the toxicity before degradation by the proportion of product not biodegraded and by the toxicity after degradation (see table ).
The study was condemned in a statement from the AIS, which maintains that the findings are based on methods which had not been verified by the scientific community. The AIS prefers to use OECD standardised tests for both biodegradability and toxicity.
While doubtful about the way the Danish organisation calculated its environmental scores, Ecover endorses the use of the Microtox test and has been working hard to get it accepted internationally. The company wants the test included in the EC eco-labelling criteria for detergents.
The current proposals, due to be presented to the European Commission by a German-led working group in September, include only absolute toxicity data for individual ingredients. The group has reservations about the Microtox method because it may not measure accurately the toxicity of less soluble ingredients in detergent formulations. Although as a test of bacterial toxicity it might be relevant to sewage treatment, the toxicity of both sludges and effluents needs also to be considered, it says.
Ecover counters that the established methods of testing for biodegradability and toxicity are too far removed from what happens when products enter the environment. It says the Microtox test is superior to assessments based on animal testing, which it refuses to support.
OECD biodegradability tests also use unrealistically high concentrations and temperatures, Ecover believes. The AIS companies, it says, have tailored the established test methods to suit their products and have not considered whether they are representative of environmental conditions.
The EDMA regards the point as fundamental and is considering non-participation in the eco-labelling scheme unless the detergent criteria are made more stringent. Ecover says it would prefer a standard which would allow only 40% of its own products to qualify for an eco-label.