There are some primary environmental factors that need to be considered when looking for a source of wool, such as the way the flock is treated for pesticides, the chemicals used in the treatment of the wool after shearing, and the distance from the source to its final destination. Sheep are often treated with insecticide and fungicide in a process called dipping. This leaves a residue on the fleece and can result in groundwater contamination if used improperly. These residues are often washed off once the fleece is sheared, but this results in three byproducts, grease, liquor, and sludge. The first two can be safely disposed of, but the latter contains remnants of the pesticides which cause a concern for disposal. When used in insulation wool is often treated with Borax to enhance its fire retardant and pest repellent qualities. Borax mining employs one of the cleanest mining techniques available and the Borax product has a low toxicity with no need for special safety precautions when handling it and requiring nothing more than washing hands and changing clothes daily after contact.