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Assessment of the consequences of a possible ban on phosphates in household detergents 1 Identification of substances for the substitution of phosphateThe identification of substances for the substitution of phosphate in detergents has been conducted as a dialog between DHI and the Association of Danish Cosmetics, Toiletries, Soap and Detergent Industries (SPT) and various representatives from the industry (2007). Focus has been on substances in laundry detergent and detergents for automatic dishwashing for consumer use. Phosphate and the alternatives for phosphates are used as builders to enhance the surfactant effect in the detergents. The role of the builders is to lower the water hardness by scavenging the calcium and magnesium ions by adsorbing or chelating them. The most important substitutes for phosphates in laundry detergents are zeolites and polycarboxylates. Others are phosphonates, carbonates and different carboxylates such as citrates and succinates. Citrates are used in certain products. The phosphonates have different properties in the laundry detergent and are normally used in very low concentrations as part of the builder system together with other complex binding substances. Sodium tartrate and sodium gluconate are only used very seldom and not considered as important substitute for phosphates. The zeolites are not used in liquid laundry products. For the liquid systems, the substitution of phosphate may take place by the use of e.g. IminoDiSuccinate (IDS). The IDS is a new chelating agent belonging to the aminocarboxylates. Usage of NTA and EDTA has not been confirmed by the industry in the products used for the Danish market neither in consumer products nor in industrial products. New environmental friendly builders are available today. The new alternatives are having a good or strong complex binding effect. They are all biological biodegradable and therefore considered as a good environmental alternative to phosphates. The most important is IminoDiSuccinate (IDS). Also Methyl Glycin Diacetic Acid (MGDA) and GLutamic acid Diacetic Acid (GLDA) are used in builder systems though it is in low amounts as the new substances are expensive alternatives to phosphates. According to the industry, substitution of phosphates in the builder system in dishwashing products may lead to a product that is not as effective as the phosphate-containing product. The alternatives are not as good as phosphates to lower the hardness of the water. Alternatives to phosphates in automatic dishwashing products are a system consisting of citrates and silicates or carbonates. IDS may also be used as alternative to phosphates in automatic dishwashing systems. A prioritized list of alternatives for phosphates according to SPT and the industry is shown in Table 1-1. Table 1-1 Gross list of identified substances for substitution of phosphate in laundry detergents and automatic dishwashing products
In a report prepared by the Swedish Chemical Agency (2006), substances for the substitution of phosphates are identified. In the report, zeolites are described as dominating alternatives for phosphate. Other alternatives are citrate, polyacrylates and to a lesser extend phosphonate and EDTA. For automatic dishwashing products, NTA is mentioned as an alternative. Table 1-2 lists the substances which are potential candidates for the substitution of phosphates in laundry detergents and detergents for automatic dishwashing (powders and tabs) with the concentration given in percentage (w/w) in the final product. The concentrations are used to calculate a risk index (R) for the individual substances in the environmental assessment of the alternative substances for phosphates. Table 1-2 List of identified substances for substitution of phosphate in laundry detergents and automatic dishwashing products. The concentration in the products is given as the typical concentration based on average values (% w/w)
As background for the environmental assessment and the impact assessment on wastewater treatment plants recipes for prototypes of laundry detergents and tabs for automatic dishwashing has been set up. The prototypes are set up both for the builder system in phosphate-free system and phosphate-containing systems. An overview of the prototypes is shown in Appendix A as well as the approximations used as the background for the assessments. [3] Not important alternative for phosphate [4] New potential alternative for phosphate, not important today [5] The potential as alternative is indicated by SPT, but not confirmed by the industry (2007)
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