June 2, 2000



FLORENCE, Italy – New studies further affirming the environmental safety of the surfactant LAS (linear alkylbenzene sulfonate) were presented at the CESIO World Congress, here May 29 – June 2.

Specifically, several studies demonstrated that LAS biodegrades satisfactorily even in anaerobic conditions, where oxygen is not present to aid biodegradation.

The Council for LAB/LAS Environmental Research (CLER) and its European counterpart, the European Centre for Studies on LAB/LAS (ECOSOL) participated in the surfactants conference as exhibitors and its representatives contributed to key presentations on the environmental safety of LAS.

“All the information presented during the CESIO congress was very favorable toward LAS,” said Tom Grumbles, chairman of CLER. “We are most optimistic about the new findings on anaerobic biodegradability of LAS.”

A poster presentation by J.L. Sanz and colleagues of the Autonomous University of Madrid reported on a study conducted on the potential of high concentrations of LAS to inhibit the anaerobic sludge digestion process. Researchers observed a 40-60% loss of LAS indicating that at least 50-70% of LAS biodegraded under anaerobic conditions.

Similarly, Irini Angelidaki and colleagues of the Denmark Technical University in Copenhagen found 14-25% removal of LAS by anaerobic sludge digesters fed high daily doses of LAS. The Danish EPA sponsored the study.

In follow up experiments to those that demonstrated 30-93% removal of LAS in anaerobic conditions over 250 days, Daniel Prats and colleagues of the University of Alicante, Spain observed 35% removal of LAS in just 21 days using the ECETOC-28 test method. These findings were reported in a poster presentation.

Based on these findings, CLER and ECOSOL are hopeful that LAS will be reclassified as anaerobically biodegradable and allow detergents made from LAS to receive certain environmentally preferred ecolabel designations, such as the White Swan in Sweden, which currently exclude products containing LAS only because of the belief it is not degradable under anaerobic conditions.

CLER and ECOSOL members also discussed with scientists the Danish executive order on concentrations of LAS in sludge used for agriculture. Independent experts at the conference were in agreement that the Danish directive was not supported by scientific evidence.

Presenting conclusions from the 1999 Danish workshop on the issue, John Solbé of Unilever stated, “We find no scientific basis for the Danish restrictions on the concentration of LAS in sludge permitted for use in agricultural soil. This is consistent with the fact that LAS has a 35 year record of safe use.” Solbé urged regulators to base their decisions on “a firm scientific footing.”