Environmental and Health Assessment of Substances in Household Detergents and Cosmetic Detergent Products
2. Consumption of detergent and cleaning products
Most detergents are formulated products containing surfactants which remove dirt, stain, and soil from surfaces or textiles. Surfactants consist of a hydrophobic and a hydrophilic component and have the ability to change the surface properties of water. In aqueous solutions, surfactants tend to accumulate at air/solution or solid/liquid interfaces, whereby the surface tension of water is reduced. The physico-chemical properties of surfactants are the basis for their numerous applications. A very important effect of surfactants in cleaning products is the wetting effect. Because of the reduced surface tension, the water can be more evenly distributed over the surface and this improves the cleaning process. The emulsifying effect of surfactants is important for both cleansing and washing of textiles. Due to the hydrophobic and hydrophilic parts, surfactants can sorb to non-polar and polar materials at the same time. During cleansing and washing, the non-polar materials are kept in emulsions in the aqueous solution and removed by rinsing. By varying the hydrophobic and hydrophilic part of a surfactant, a number of properties may be adjusted, e.g. wetting effect, emulsifying effect, dispersive effect, foaming ability and foaming control. Surfactants are grouped according to their ionic properties in water:
 | Anionic surfactants have a negative charge |
| Nonionic surfactants have no charge |
| Cationic surfactants have a positive charge |
| Amphoteric surfactants have positive or negative charge dependent on pH |
The two major markets, household detergents and industrial and institutional cleaning products, consume more than 1 million and more than 200 thousand tons surfactants, respectively, in Europe (Morse 1999). The formulations, or products, in which these volumes are used, differ markedly in their contents of surfactants. E.g., a liquid product may contain approximately 50% surfactant compared to less than 25% in powders. The consumption of various household detergent products is estimated below by inclusion of figures from several sources (Table 2.1).
Table 2.1
Estimated annual consumption of household detergents.
Product |
Annual consumption (tons) |
|
|
Denmark (1997) |
Europe (1998) |
Laundry detergents, powders |
28,700 |
3,100,000 |
Laundry detergents, liquids |
4,900 |
560,000 |
Laundry detergents, specialty products |
3,200 |
- |
Fabric softeners |
9,100 |
1,000,000 |
All-purpose cleaning agents |
5,100 |
950,000 |
Toilet cleaning agents |
2,300 |
400,000 |
Hand dishwashing agents |
6,000 |
800,000 |
Machine dishwashing agents |
3,800 |
500,000 |
Personal care products |
14,200 |
1,900,000 |
The diversity of products to perform basic cleaning tasks in the house is growing, and
soap and detergent producers renew their product lines by introducing new additives,
improved surfactants, or new formulations to enhance performance. Several trends influence
the development of consumer detergent products, e.g.:
| Multifunctional chemicals with the ability to serve multiple functions in the product will reduce the number of raw materials and, hence, reduce the formulation costs |
| Formulation of chemicals that can be used as ingredient alternatives in the products in order to increase flexibility and independence of suppliers |
| Adjustment of existing formulations, e.g. by introduction of new additives or surfactants, or by utilizing synergistic effects between ingredients |
Mildness is an important property that plays a significant role for the use of surfactants in household products. Today, anionic surfactants are used in the largest volume, but the growth of anionic surfactants is expected to be relatively slow in the next few years, as they are gradually replaced by milder nonionic and amphoteric surfactants. The trend towards milder surfactants has already favoured the use of specific surfactant types. Mild components such as the amphoteric surfactants, alkyl betaines and alkylamido betaines, as well as the anionic surfactants, a -olefin sulfonates (AOS), are used in increasing volumes and the consumption of these chemicals is expected to grow (Morse 1999). The consumption of surfactants in household and in industrial and institutional detergents is estimated below by inclusion of figures from several sources (Table 2.2-2.3).
Table 2.2
Estimated consumption of surfactants in household detergents.
Surfactant |
Annual consumption 1998 (tons) |
||
Denmark |
Europe |
||
Anionic surfactants, subtotal |
8,700 |
780,000 |
|
|
AES |
1,800 |
123,000 |
|
AS |
1,000 |
117,000 |
|
LAS |
3,500 |
330,000 |
|
SAS |
600 |
55,000 |
|
Soap |
1,600 |
134,000 |
|
Other |
200 |
21,000 |
Nonionic surfactants, subtotal |
6,000 |
530,000 |
|
|
AE+AA |
5,400 |
455,000 |
|
APG |
200 |
28,000 |
|
FAGA |
200 |
28,000 |
|
Other |
200 |
19,000 |
Cationic surfactants, subtotal |
1,200 |
98,000 |
|
Amphoteric surfactants, subtotal |
460 |
40,000 |
|
Total |
16,360 |
1,448,000 |
|
Table 2.3
Estimated consumption of surfactants in industrial and institutional products.
Surfactant |
Annual consumption 1998 (tons) |
||
Denmark |
Europe |
||
Anionic surfactants, subtotal |
1,400 |
128,000 |
|
|
LAS |
800 |
80,000 |
|
Soap |
250 |
22,000 |
|
Other |
350 |
26,000 |
Nonionic surfactants |
1,100 |
96,000 |
|
Cationic surfactants |
200 |
17,000 |
|
Amphoteric surfactants |
80 |
7,000 |
|
Total |
2,780 |
248,000 |
|