Dimethyl sulfoxide

Endpoint summary

Additional information

Based on the intrinsic properties (low Log Kow, high water solubility, not persistent) the DMSO is not expected to sorb on soil particles. The DMSO show a very low toxicity in acute aquatic tests. According to the ITS Figure and table R7.11-2 of the ECHA guidance R7c, the substance fall into the hazard category 1 no testing are necessary. It is laid down in the REACh Regulation EC 1907/2006 Annexes IX and X, section 9.4., column 2, that terrestrial toxicity testing shall be proposed by the registrant if the chemical safety assessment (CSA) indicates such a need. Since the CSA indicates no risk for soil, no terrestrial toxicity testing is needed.

 

Toxicity to terrestrial species has not been deeply assessed on DMSO even if some indirect exposure can occur when used as co-formulant of agrochemical formulations. Nevertheless in this case DMSO toxicity is indirectly assesssed through agrochemical formulation testing. Otherwise, based on the identified uses, terrestrial compartment is not considered to be the final destination compartment for DMSO. Exposure is therefore unlikely.

No reliable studies were identified. Nevertheless some elements can be traced in the US EPA pesticide inert re-assessment finalized in 2006 (http://www.epa.gov/opprd001/inerts/decisiondoc_a2k.html).

 

Using mammals as a surrogate for birds and other terrestrial phase animals (eg. Reptiles), DMSO is likely to be practically non toxic on an acute ingestion basis.

 

In a study looking at the mortality of mature earthworms (Eisenia fetida), no effects were reported at the highest dose tested after over 48 hours exposure to DMSO in a 2-propanone carrier. The LC₅₀was characterized as > 1000 µg/cm². In a study of lethality in newts, rough-skinned newts (Taricha granulosa) were dosed once interperitoneally and observed for 300 days. Survival was affected at a lethal threshold concentration (LETC) of 15 g/kg. In the same study, the newts were immersed in solutions of DMSO ranging from 0.1 to 9% and observed for mortality over 300 days. The LETC was determined to be 2% for survival. Finally, in the same study, newts were intravenously injected with DMSO at 15 mg/kg once and followed for 43 days; the study also included a control group. At the end of the exposure period, all animals were sacrificed and organs were weighed and compared to whole body weight for the control and treated groups. Little difference was seen in the percent lipid fat, liver and spleen weights between control and treated groups.

 

In several studies looking at the effects of DMSO over 10 days on germination of butter print, green amaranth, ragweed, quackgrass, common morningglory, narrowleaf plantain, field sorrel, curley dok, giant bristlegrass, green foxtail, Johnson grass, and Jimsonweed seeds by fumigation, no effects were reported at a dose up to 1 mL. Details of the study design were insufficient to determine the application rate equivalent or fumigant concentration.

In a 28 day study in Jimsonweed seedlings, concentrations equivalent to 2% in formulation sprays applied to the plants resulted in no effects on chlorophyll production and biomass, but did should a slight decrease in stem plant size (11%) when compared to controls. In a study varying in duration from 5 to 19 days, wild carrot, soybean and lettuce, plants were soaked/dipped in a solution of 1% to 2% DMSO to determine the effects on biomass at the cellular level. Results indicated effects were likely at the 2% dose, however it was inconclusive as to whether these effects would result in long term impacts to the plants or its ability to reproduce. Further review of the supporting literature is necessary before a definitive conclusion can be made.