Appendices 1-18 to: Report on the Health Effects of Selected Pesticide Coformulants

Appendices 1-18 to: Report on the Health Effects of Selected Pesticide Coformulants

22 Evaluation

As DME is a gas at ambient temperature, the main exposure routes for humans seem to be by inhalation and accidental dermal contact occurring from the use of DME as a carrier of active substances in aerosols.

The critical target organ at acute high concentrations is the CNS resulting in a narcotic effect. No contemporary human data are available in relation to CNS changes such as neurobehavioral disturbances.

Based on the limited and old data on human exposure to dimethyl ether it is not possible to estimate levels for the narcotic effects in humans.

The structurally related substance – diethyl ether – has been more extensively investigated according to narcotic effects, where exposure to concentrations of about 100000 ppm (308000 mg/m³) induces anaesthesia, and about 15000 ppm (46200 mg/m³) is the lowest anaesthetic concentration. (Strube 1995).

Available animal studies show a low order of acute and chronic toxicity, and any capability of dimethyl ether in being a genotoxic, carcinogenic or developmental toxicant has not been demonstrated.

Repeated dose toxicity studies have shown some effects of high concentrations of dimethyl ether on the liver (higher SGPT (= alanine amino transferase ALAT) and SGOT (= aspartate amino transferase (ASAT) values suggesting a possible onset of a hepatotoxic effect) and changes in white blood cell counts. The no-effect level in subchronic studies for haematological effects was reported to be 10000 ppm (19000 mg/m³) for rats and 5000 ppm (9600 mg/m³) for hamsters. In a 30-week study on rats, the no-effect level for increased levels of SGPT was reported to be 2000 ppm (3800 mg/m³) and for increased levels of SGOT 200 ppm (380 mg/m³). In a life-time study in rats, the no-effect level was stated to be 20000 ppm (38000 mg/m³); haematological investigations showed no evidence of changes, whereas no information is given whether biochemical parameters (as e.g., SPGT and SGOT) were investigated.

Overall, the no-effect level for effects of dimethyl ether in repeated dose toxicity studies is considered to be 2000 ppm (3800 mg/m³) based on the increased levels of SPGT observed at higher concentrations in the subchronic studies.