Biocide

A biocide is a chemical substance capable of killing different forms of living organisms used in fields such as medicine, agriculture, forestry, and mosquito control.

A biocide can be:
 * A pesticide, which includes fungicides, herbicides, insecticides, algicides, molluscicides, miticides and rodenticides.
 * An antimicrobial, which includes germicides, antibiotics, antibacterials, antivirals, antifungals, antiprotozoals and antiparasites. See also spermicide.

Uses
Biocides can also be added to other materials (typically liquids) to protect the material from biological infestation and growth. For example, certain types of quaternary ammonium compounds (quats) can be added to pool water or industrial water systems to act as an algicide, protecting the water from infestation and growth of algae. Chlorine can be added in low concentrations to water as one of the final steps in wastewater treatment as a general biocide to kill micro-organisms, algae, etc. It is often impractical to store and use poisonous chlorine gas for water treatment, so alternative methods of effectively adding chlorine are used. Adding hypochlorite solutions to pools, etc. is one possible solution. Hypochlorite can gradually release chlorine into the water. Even more convenient for some users are compounds such as sodium dichloro-s-triazinetrione (dihydrate or anhydrous), sometimes referred to as dichlor, and trichloro-s-triazinetrione, sometimes referred to as trichlor. These compounds are stable while solid and may be used in powdered, granular, or tablet form. When added in small amounts to pool water or industrial water systems, the chlorine atoms hydrolyze from the rest of the molecule forming hypochlorous acid (HOCl) which acts as a general biocide killing germs, micro-organisms, algae, etc. Halogenated hydantoin compounds are also used as biocides.

European Community Classification
The Biocidal Products Directive 98/8/EC (BPD), the classification of biocides is broken down into 23 product types (i.e. application categories), with several comprising different subgroups:

MAIN GROUP 1: Disinfectants and general biocidal products


 * Product-type 1: Human hygiene biocidal products
 * Product-type 2: Private area and public health area disinfectants and other biocidal products
 * Product-type 3: Veterinary hygiene biocidal products
 * Product-type 4: Food and feed area disinfectants
 * Product-type 5: Drinking water disinfectants

MAIN GROUP 2: Preservatives


 * Product-type 6: In-can preservatives
 * Product-type 7: Film preservatives
 * Product-type 8: Wood preservatives
 * Product-type 9: Fibre, leather, rubber and polymerised materials preservatives
 * Product-type 10: Masonry preservatives
 * Product-type 11: Preservatives for liquid-cooling and processing systems
 * Product-type 12: Slimicides
 * Product-type 13: Metalworking-fluid preservatives

MAIN GROUP 3: Pest control


 * Product-type 14: Rodenticides
 * Product-type 15: Avicides
 * Product-type 16: Molluscicides
 * Product-type 17: Piscicides
 * Product-type 18: Insecticides, acaricides and products to control other arthropods
 * Product-type 19: Repellents and attractants

MAIN GROUP 4: Other biocidal products


 * Product-type 20: Preservatives for food or feedstocks
 * Product-type 21: Antifouling products
 * Product-type 22: Embalming and taxidermist fluids
 * Product-type 23: Control of other vertebrates

Literature

 * Wilfried Paulus: Directory of Microbicides for the Protection of Materials and Processes. Springer Netherland, Berlin 2006, ISBN 1-4020-4861-0.
 * Danish EPA (2001): Inventory of Biocides used in Denmark