OMYA's biocides are classified as "pesticides" by the state of Vermont
Within the "pesticide" classification, they fall under the "Cooling Tower" category

Cooling Tower Pesticides used in Rutland County in 2000
in Pounds of Active Ingredients

2-Methyl-4-isotiazolin-3-one 84.35
5-Chloro-2-methyl-4-isothiazolin-3-one 277.14
Dazomet 90,767.37
Sodium O-phenylphenate 73,155.80
Sodium hypochlorite 162,877.00
TOTAL 327,161.66

Data from Vermont Department of Agriculture
October, 2001