The results of many years of systematic monitoring of the Rhine River demonstrate a dramatic decline of more than 90 percent in the volume and concentrations of LAS and almost all detergent-related substances, according to Germany’s Henkel KGaA.
Two factors are held primarily responsible for the decline: 1) the higher ecological quality of the detergents and their ingredients, and 2) the quantitative and qualitative improvement of waste water treatment. High rates of biodegration also were cited.
The Rhine study, involving some 140 sampling points along the river and its major tributaries, was supplemented more recently bu studies of the Rur and other smaller rivers receiving considerable volumes of sewage, often reflecting “worst case” values. The results were equally encouraging, showing predicted no-effect concentrations (PNEC) for LAS of between 0.09 and 0.24 ppm, considerably below the “critical” limit of 1.0. This demonstrates that LAS (and other surfactants) present no ecotoxicological risk and “no cause for concern,” according to the study.¹
The Henkel reports conclude that “the concentrations of all surfactants in the aquatic environment are very low (<6µg/1)… (and) are of no immediate concern.”
The Rur study indicated that more than 90 percent of LAS was successfully eliminated in treatment facilities, confirming the findings of the ERASM ² studies in five European countries, which found an average eliination rate of 99.2 percent. The Rur study also found that colder temperatures appeared to have no effect on surfactant concentrations.
Moreover, rates of biodegration of LAS and other surfactants in river water were found to be rapid. Halflives, the time required for half the surfactant to biodegrade, was found to be 1-3 hours.
1) The Rhine and Rur studies were described in detail by Dr. F.R. Schröder in Tenside Det. Surf., 32 (1995) 492-497, SOFW Journal, 121 (1995) 420-427.
2) Environmental Risk Assessment Steering Committee of AIS/CESIO (J. Waters and T.C.J. Feijrel, Chemosphere 30 (1995) 1939-1956.
A thorough environmental risk assessment of LAS was recently completed by the Soap and Detergent Association of the United States (SDA) and published as a monograph titled “Linear Alkylbenzene Sulfonate.” The assessment concludes:
“The environmental risk assessment for LAS is based on an extensive data base, probably more so than for any other chemical, and the risk assessment substantiates the environmental acceptability of LAS use in U.S. detergents and household cleaning products. The comprehensiveness of the studies carried ou on LAS provides documentation of the environmental safety of LAS that is rarely available for chemicals in commerce.”
Among specific findings of the risk assessment were these:
- LAS readily undergoes primary and ultimate biodegradation under a wide variety of wastewater treatment processes.
- Traces of LAS ans LAS biodegradation intermediates in effluents from municipal wastewater treatment facilities continue to biodegrade in receiving water environments.
- Recent monitoring studies from the Mississippi River and from 50 sites in the U.S. confirm that LAS is not accumulating in river waters or sediments.
- LAS is not impacting sediment organisms in the Mississippi River despite the large wastewater input and the lack of secondary treatment by several large metropolitan cities along the river.
- LAS applied to soils via sewage sludge biodegrades quickly, with halflives of between 7 and 22 days. No potential for groundwater contamination was indicated.
- LAS concentrations in sediments below activated sludge treatment facilities are 10 to 100 times lower than NOEC’s (no observable effect concentrations).
For further information regarding the SDA monograph please contact The Soap and Detergent Association, 475 Park Avenue South, New York, NY 10016.
In its end-of-year report, Britian’s Department of the Environment states that LAS is “readily biodegradable” and its widespread use in consumer products “poses no hazard to human health or the environment.”
This conclusion by the department’s technical committee on detergents and the environment follows an extensive review of the research and published literature, including the proceedings of several international symposia.
LAS has remained the major surfactant throughout the world, the report notes, because of its effectiveness, versatility, cost/performance and environmental safety.
These conclusions of Britain’s Department of the Environment are similar to other recent findings by the European Union, the Netherlands, and the Environmental Protection Agency of the United States. (August 1995)
A working group of the Organization for Economic Cooperation and Development (OECD) and the U.S. Environmental Protection Agency reached agreement on a risk assessment for LAB, classifying it in Category 1 of the OECD/SIDS (screening information data set) risk assessment document. This means that LAB is considered of low potential risk and low priority for further assessment. (June 1995)
The Netherlands government has concluded that there is no significant environmental risk from LAS or other large-volume surfactants used in laundry detergents. A comprehensive risk assessment found that LAS, alcohol ether sulfates and soap are all efficiently removed (over 99%) in sewage treatment systems. (June 1995)
The Dutch Environmental Ministry (VROM) has concluded that the environmental risk of LAS and other currently used laundry and cleaning product ingredients is “low” and “acceptable in every respect.” This conclusion is based on joint risk assessments conducted by VROM and cleaning products: linear alkylbenzene sulfonate (LAS), alcohol ethoxylates, alcohol ether sulfates and soap. The conclusions were announced by Margaretha de Boer, the Minister of VROM, in a letter to the Dutch Parliament.
The risk assessments were initiated in 1991 as part of a plan to evaluate all components of laundry and cleaning products, beginning with the largest volume ingredients. The four surfactants chosen for the first round of assessments represent over 80% of the total volume of surfactants used in laundry and cleaning products.
The first step in the risk assessments was a comprehensive inventory of all the aquatic toxicity data on the four surfactants, including data and comments submitted by CLER member companies. From a review of this data, the Maximum Tolerable Risk (MTR,) or maximum safe level, was determined for each surfactant in surface waters. Next, monitoring studies conducted at seven treatment plants showed that the four surfactants were almost completely removed (99.1-99.8%) in sewage treatment. Based on these results, the expected concentrations in surface waters immediately downstream of sewage the treatment plants in The Netherlands are a factor of 100 lower than the MTR levels. Since the predicted environmental concentrations are lower than the maximum safe levels, the surfactants are judged to be safe.
Because surfactants are the highest volume ingredients in laundry and cleaning products, VROM has decided that there is no need to conduct an extensive assessment of the remaining ingredients. (December 1995)
The Regulatory Commission on Ecolabeling for the European Union completed its work on establishing ecolabel criteria for laundry detergents. The criteria affirm the environmental acceptability of LAS, thus ensuring that detergent products made with LAS will qualify for the EU ecolabel. (June 1995)
LIFE CYCLE STUDY FINDS ENVIRONMENTAL CLAIMS MADE FOR CERTAIN SURFACTANTS LACK SCIENTIFIC BASIS:No Surfactant Found Superior to LAS
The most comprehensive Life Cycle Inventory (LCI) study ever conducted on the major surfactants used in laundry detergents has just been completed in Europe. LAS and six other surfactants were studied. The LCI study is a compilation of all the energy and raw materials consumed and all emissions to air, water and solids produced in the manufacturing of the surfactants.
The study found that there is no scientific basis to conclude that any surfactant is environmentally superior: all consume natural resources and produce various wastes. This finding contradicts frequently made claims that various surfactants or groups of surfactants, such as palm or coconut oil-based surfactants, are environmentally superior. Such claims have typically been made based on the consideration of one or only a few attributes of the surfactant. The power of the LCI study is that it systematically considers all environmental aspects of the production process and thus provides a comparison across all attributes.
The study provides a benchmark for surfactant producers to use in improving their manufacturing processes. Specifically regarding LAS, the study commented: “LAS, as with most of the petrochemical-derived surfactants, is produced in technologically well advanced processes … leading to reduced environmental emissions.”
The LCI study was conducted by Franklin Associates, a leading environmental consulting firm, under the supervision of a work group of the European Chemical Industry Council (CEFIC) and the European Center of Studies on LAB/LAS (ECOSOL). All the major surfactant manufacturing companies in Europe participated in the study. The first part of the study was published in the February, 1995, issue of the scientific journal, Tenside Surfactants Detergents. The final part was presented in a workshop in Brussels at the end of October. (November 1995)
The results of a monitoring study at ten U.S. sewage treatment plants have confirmed the environmental safety of linear alkylbenzene sulfonate (LAS) and dialkyltetralin sulfonate (DATS), a co-product of LAS manufacturing. In this study, the levels of LAS, DATS and their biodegradation intermediates were measured in raw sewage coming into treatment plants, treated water leaving the plants, and river water both upstream and downstream of the mixing zones where treated water is discharged into rivers and streams. This is the first study to measure real world levels of DATS and DATS intermediates in these environments.
The results of this study demonstrate that, due to effective biodegradation and removal in sewage treatment, concentrations of LAS, DATS and their biodegradation intermediates are very low (parts per billion range) in the rivers and streams receiving treated water. A previously reported study (Rapaport et al., 1992) has demonstrated that these trace levels of LAS, DATS and their intermediates pose no risk to aquatic or other environmental organisms. Other studies (Nielsen et al., 1992, 1993) have demonstrated that these trace levels will continue to biodegrade until they have mineralized into carbon dioxide, water and sulfate salts, materials harmless to the environment.
The monitoring study was sponsored by the Council for LAB/LAS Environmental Research (CLER) and the Procter & Gamble Company. The report has just been accepted for publication and will appear in the March, 1996, issue of the technical journal, Environmental Toxicology and Chemistry.
Geological Survey reports improved water quality
The latest study of the Mississippi River by the U.S. Geological Survey, published earlier this year, concludes that the rapid biodegradation of LAS has contributed significantly to improvement in the rivers water quality in recent years, despite a more than 30 percent increase in surfactant consumption.(1)
Concentrations of anionic surfactants (MBAS)(2) in the river have continued to decrease since 1972, and show a substantial drop since 1990, the study reports, despite increased populations and use. Druing the 1991-92 period, concentrations ofanionic surfactants were as low as 20 to 100 parts per billion, well below the drinking water standard of 500 parts per billion.
LAS concentrations in the river also were found to be very low. LAS was detected in only 16% of mainstream grab samples, at concentrations ranging from 0.1 to 10.3 parts per billion.
Although measurable concentrations of LAS were found near the major population centers of Minneapolis, St. Louis and New Orleans, LAS concentrations fell to below detectable levels within 80 km downstream from these sources as a result of dilution and instream biodegradation.
Concentrations of LAS in bed sediments ranged from about 0.1 to 1 part per million of sediment. Biodegradation continued to remove LAS from the sediment, the study found, but rates of biodegradation varied with river conditions.
The study notes that EDTA(3), the dissolved organic chemical generally considered to be an indicator of industrial contamination, is found in the Mississippi at about one-fourth of the concentration found in some European rivers.
1. Contaminants in the Mississippi River, 1987-92 / edited Robert H. Meade (U.S. Geological Survey circular: 1133); C.F. Tabor and L.B. Barber, II, Environ.Sci. Technol., 30(1996) 161-171. 2. Methylene-blue-active substances, a measure of anionic surfactant concentrations. 3. Ethylenediaminetetraacetic acid.
SOAP AND DETERGENT ASSOCIATION AFFIRMS SAFETY OF LAS
The U.S. Soap and Detergent Association recently completed a risk assessment monograph, “Linear Alkylbenzene Sulfonate Environmental Safety Summary,” which “substantiates the environmental acceptability of LAS use in detergents and household cleaning products.” It notes that the extensive database documenting the environmental safety of LAS is probably greater than for any other chemical.
“REAL WORLD” STUDIES IN SEVEN COUNTRIES FIND LAS BIODEGRADES RAPIDLY IN RIVERS, STREAMS
Five major studies of the environmental fate of LAS in rivers and streams in the United States, Japan and five European countries — Germany, Italy, the Netherlands, Spain and the United Kingdom — appear in the February 1997 issue of The CLER Review.
Together, the studies of more than 60 sewage treatment facilities in Europe and the U.S., and monitoring of miles of rivers and streams receiving treated wastewater, indicate substantial “real world” evidence that LAS biodegrades rapidly and poses little or no threat to aquatic ecosystems.
The U.S. and European studies demonstrate that LAS is effectively removed in most sewage treatment processes. Levels of LAS detected in receiving waters were well below those known or predicted to cause any adverse effects for aquatic or sediment organisms. In one study, LAS intermediates and DATS, a component of commercial LAS, were also shown to be significantly removed. High rates of biodegradation of LAS and other detergent surfactants were observed in river water.
“Biofilm” speeds biodegradation
In Japan, scientists at the Tokyo University of Agriculture and Technology studied LAS in a shallow urban stream receiving untreated household wastewater. They found an extremely rapid rate of biodegradation, which could not be duplicated in standard laboratory tests. Further research found that the rapid biodegradation was due to a “biofilm” of micro-organisms on the stream bed. The researchers conclude that this layer of biofilm also may be effective in the removal of other chemicals introduced into urban streams on a continuing basis.