Linear alkylbenzene sulfonate (LAS) is said to be the most used surfactant in the world for laundry detergent formulations. It has been used since the 1960's, and worldwide consumption is estimated to be around 2.8 million tons a year. LAS is staunchly defended by all surfactant and detergent makers, by the US Detergent and Soap Association and various industry supported groups such as CLER. These companies and organizations have sponsored much research in support of LAS's continued acceptance as a "safe" cleaning agent for laundry detergents. Few environmental protection agencies or even environment groups have come out with a comprehensive movement to get detergent manufacturers to stop using LAS in their detergent formulations.
LAS in Water of Lake Dainchi
Very eye-opening article published in January of this year about the effects of linear alkylbenzene sulfonate (LAS) done by a group of researcher from the Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China.
Lake Dainichi is the biggest lake in Yunnan Province, and the 6th biggest freshwater lake in China. It covers a surface area of approximately 300km, in terms of comparison, it is app. 3/5 the size of Lake Tahoe, North America's biggest Alpine lake. Lake Dainichi is being filled with untreated municipal and industrial sewage flows and LAS is one of the major chemical contributors. "There is about 2,276 tons of washing powder draining into Lake Dainchi every year". Researchers have found the level of LAS in Lake Dainichi has gone up 2.4 times since 1995 and the data they collected on the amounts of LAS they measured clearly threatens the life of the lake unless something is done immediately. Lake Dainichi is representative of many of China's eutrophic inland lakes that is being threatened by the overuse of surfactants in laundry detergents.
The data shows that the range of LAS in various areas of the lake ranged from 18.1 to 260.1 ug/l (micrograms per liter or ppb) and the average concentration was 52.6 ug/l. This converts to a minimum of 0.0181 mg/l to 0.26 mg/l (milligrams per liter or ppm). In polluted rivers running into Lake Dainchi, levels as high as 2.1 mg/l (2.1 ppm) were recorded.
"LAS is regarded as a toxic substance for aquatic organisms. A previous study (Lewis 1991) indicated that the chronic and sub-lethal toxicity of LAS to aquatic animals occurred at very low concentrations, such as 0.1 and 0.0002 - 40mg L, respectively. Venhuis and Mehrvar (2004 reported that 0.02 - 1.0mg/L LAS in aquatic environment can damage fish gills, cause excess mucus secretions, decrease respiration in the common goby, and damage swimming patterns in blue mussel larva. Van de Plassche et al. (1999) reported final no-effect concentration (NEC) of 0.25mgL (-1) for LAS to aquatic organisms. Belanger et al. (2002) estimated a NEC of 0.293 mg L(-1) which was based on a broad array of organisms (e.g.algae and invertebrates) that responded in similar time frames and concentrations. Jorgensen and Christoffersen (2000) observed that LAS had a negative impact on the survival of heterotrophic nanoglagellates and ciliates at very low concentrations under field conditions (the NEC as low as 0.02 mg L (-1) They also demonstrated that NEC appeared to be lower in field tests than for similar organisms tested under laboratory conditions. Moreover, several studies had demonstrated that some responses, such as swimming activity and weight gain in fish, were impaired when chronically exposed to 0.2 mg L(-1) LAS. In China, the Environmental Quality Standards for Surface Water specifies a value of 0.2 mg L(-1) for fresh water . The present study showed that LAS in Lake Dianchi may have potential ecologic risk since (1) the rapid increasing trend was found in the lake during (the)past decade and (2) the concentration of LAS in the lake may be close to the reported toxic levels. Thus, the pollution of LAS in this lake should receive more attention by government to reduce pollution levels in the lake. In this kind of situation, according to the dynamics of the LAS in different parts of the lake, the government needs to improve the efficiency and capability of sewage treatment plants to pre-treat wastewater containing LAS before they enter the lake, especially in the Northwest. Fortunately, several programs for river cleaning have been initiated recently by local government."
LAS Is More Eco-Toxic Than Arsenic
There are several points that need to be stressed from the above findings:
1. The evidence that laundry detergent is the source of this pollution was substantiated by the amount of other ingredients found in laundry detergents such as phosphates and nitrogen. Data collected over 4 years showed, "Concentration of LAS was positively correlated with TP (total phosphate), TN (total nitrogen), and NH4+-N of 22 sampling sites in Lake Dianchi for four seasons combined. "
2. The study quotes only a few of many studies that have taken place through the years that confirm exactly how toxic LAS is to marine life. The Lewis study shows certain aquatic animals are effected in amounts as low as 1 part LAS for 10 million parts water. (half a pint of LAS poured into an olympic-sized pool, would get a reading of 1.04 parts per 10 million). While there may exist chemicals that are more toxic to marine life than LAS, you will not find it in the same abundance as LAS, and, with the potential to do as much harm to ourselves and the environment. Compare LAS to arsenic for example, a much more well known poison. Research generally shows LC50 of Daphnia magna (water fleas) when exposed to LAS is somewhere in the range of 3.6 to 4.7ppm (mg/L). For Arsenic, it's around 7.4 - 7.5ppm. LAS is twice as toxic for marine life than arsenic. In this context, it is outrageous that detergent manufacturers continue to be the main players in putting over 5 billion pounds of LAS into our environment year after year for over 40 years.
3. Supporters of LAS will quickly point out LAS can not be found in the same concentrations in the waters of developed countries which have better waste water treatment facilities. They will also tell you it quickly biodegrades so it is safe. This should not be good enough for regulators to keep allowing the use of LAS. In all water located near human populations that use detergent, LAS can be found. In river bank sediment, where the lack of air decreases greatly LAS's ability to biodegrade, dangerously high levels of LAS can be found, well in excess of 100mg/L (in major tributaries like the Mississippi), much higher than what aquatic animals can bear. Obviously during times of heavy rain and flooding, this sediment mixes back into water. What happens to grey water still in drainage systems when it rains heavily and the drains overflow? It must run directly into creeks and rivers without ever going through a waste-water treatment plant, causing levels of surfactants in water to spike, and in some cases leading to large fish kills. More alarming however is the appearance of frogs with 6 legs and male fish carrying fish eggs. Mutations among these species are indicators that all water creatures are being effected by pollutants and there is enough evidence and data to say surfactants are among the most common and deadly.
Major detergent makers can come up with much safer formulations and regulators and consumers must persuade them to do so.