What type of system do handlers use when properly mixing pesticides packaged in water-soluble packets?

Handlers use a closed mixing system when properly mixing pesticides packaged in water-soluble packets because this method minimizes the risk of exposure to pesticide residues during the mixing process. In a closed mixing system, the materials are contained within a sealed environment, which not only protects the handler from potential chemical contact but also reduces the likelihood of environmental contamination.

This approach is particularly important for water-soluble packets, as these packets dissolve in water, allowing for the safe mixing of the pesticide without releasing harmful particles or vapors into the air. Additionally, a closed system often incorporates features that facilitate precise measurements and mixing, further ensuring application accuracy and safety.

The other options refer to different mixing methods that do not provide the same level of safety or containment. Open mixing systems expose handlers to potential pesticide exposure, and manual mixing systems may lack the protective features found in closed systems. Chemical mixing systems could imply various handling methods but do not specifically pertain to the safe practices used for water-soluble packets.