DOWANOL, an environmentally safe adjuvant

Abstract

AbstractPesticide spray formulations include a variety of adjuvants as wetting agents, surfactants or emulsifiers. DOWANOL TPM (tripropylene glycol methyl ether) is one such adjuvant in current common use in spray formulations of the insecticide fenitrothion. Unlike some other adjuvants which we have tested, DOWANOL appears to have no significant toxicity for duckweed, Lemna minor L., an environmentally important aquatic plant, which has been previously shown to be sensitive to some formulations. Four parameters were monitored, namely, biomass, photosynthetic function, adenosine triphosphate level and changes in the electrical potential of the bathing media. Reported concentrations of DOWANOL in forest pools after spraying are of the order of 1 μg ml−1. We have tested concentrations up to 956 μg ml−1. The highest concentration produced significant functional impairment in the plants, which, however, recovered within 2 d in freshwater. Lower concentrations had no measurable effects. The threshold concentration for DOWANOL toxicity to Lemna is thus about three orders of magnitude higher than observed field concentrations, and we conclude that it therefore can be judged to be a relatively environmentally safe adjuvant.