Polyhexamethylene guanidine (PHMG) is a

guanidine Guanidine is the compound with the formula HNC(NH2)2. It is a colourless solid that dissolves in polar solvents. It is a strong base that is used in the production of plastics and explosives. It is found in urine predominantly in patients experie ...

derivative that is used as a biocidal

disinfectant A disinfectant is a chemical substance or compound used to inactivate or destroy microorganisms on inert surfaces. Disinfection does not necessarily kill all microorganisms, especially resistant bacterial spores; it is less effective than st ...

, often in the form of its

salt Salt is a mineral composed primarily of sodium chloride (NaCl), a chemical compound belonging to the larger class of salts; salt in the form of a natural crystalline mineral is known as rock salt or halite. Salt is present in vast quantitie ...

polyhexamethylene guanidine phosphate (PHMG-P). Studies have shown that PHMG in solution has

fungicidal Fungicides are biocidal chemical compounds or biological organisms used to kill parasitic fungi or their spores. A fungistatic inhibits their growth. Fungi can cause serious damage in agriculture, resulting in critical losses of yield, quality, ...

as well as

bactericidal A bactericide or bacteriocide, sometimes abbreviated Bcidal, is a substance which kills bacteria. Bactericides are disinfectants, antiseptics, or antibiotics. However, material surfaces can also have bactericidal properties based solely on their ...

activity against both

Gram-positive In bacteriology, gram-positive bacteria are bacteria that give a positive result in the Gram stain test, which is traditionally used to quickly classify bacteria into two broad categories according to their type of cell wall. Gram-positive bacte ...

and

Gram-negative bacteria Gram-negative bacteria are bacteria that do not retain the crystal violet stain used in the Gram staining method of bacterial differentiation. They are characterized by their cell envelopes, which are composed of a thin peptidoglycan cell wall ...

. The substance also has

detergent A detergent is a surfactant or a mixture of surfactants with cleansing properties when in dilute solutions. There are a large variety of detergents, a common family being the alkylbenzene sulfonates, which are soap-like compounds that are more ...

, anti-corrosive, and flocculant properties and prevents

biofouling Biofouling or biological fouling is the accumulation of microorganisms, plants, algae, or small animals where it is not wanted on surfaces such as ship and submarine hulls, devices such as water inlets, pipework, grates, ponds, and rivers that ...

. PHMG-P is a white powdered solid, and as all polyguanidine salts, readily soluble in water.

Toxicity

Unlike the related polymer

polyhexanide Polyhexanide (polyhexamethylene biguanide, PHMB) is a polymer used as a disinfectant and antiseptic. In dermatological use, it is spelled polihexanide (INN) and sold under the names Lavasept, Serasept, Prontosan, and Omnicide. PHMB has been shown ...

(PHMB), PHMG has been described as a relatively new compound with properties, potency, and effects being not yet fully recognized. Preliminary findings indicate that PHMG and its derivatives primarily rely on damaging the

cell membrane The cell membrane (also known as the plasma membrane (PM) or cytoplasmic membrane, and historically referred to as the plasmalemma) is a biological membrane that separates and protects the interior of all cells from the outside environment ( ...

by inhibiting the activity of cellular

dehydrogenase A dehydrogenase is an enzyme belonging to the group of oxidoreductases that oxidizes a substrate by reducing an electron acceptor, usually NAD+/NADP+ or a flavin coenzyme such as FAD or FMN. Like all catalysts, they catalyze reverse as well as f ...

s. When PHMG is aerosolized and inhaled, it harms the lungs, causing death of the cells lining the

bronchioles The bronchioles or bronchioli (pronounced ''bron-kee-oh-lee'') are the smaller branches of the bronchial airways in the lower respiratory tract. They include the terminal bronchioles, and finally the respiratory bronchioles that mark the start o ...

and widespread damage to

alveoli Alveolus (; pl. alveoli, adj. alveolar) is a general anatomical term for a concave cavity or pit. Uses in anatomy and zoology * Pulmonary alveolus, an air sac in the lungs ** Alveolar cell or pneumocyte ** Alveolar duct ** Alveolar macrophage * ...

, along with

bronchiolitis obliterans Bronchiolitis obliterans (BO), also known as obliterative bronchiolitis, constrictive bronchiolitis and popcorn lung, is a disease that results in obstruction of the smallest airways of the lungs (bronchioles) due to inflammation. Symptoms include ...

, an often fatal form of non-reversible obstructive

lung The lungs are the primary organs of the respiratory system in humans and most other animals, including some snails and a small number of fish. In mammals and most other vertebrates, two lungs are located near the backbone on either side of t ...

disease in which the bronchiole are compressed and narrowed by

fibrosis Fibrosis, also known as fibrotic scarring, is a pathological wound healing in which connective tissue replaces normal parenchymal tissue to the extent that it goes unchecked, leading to considerable tissue remodelling and the formation of perma ...

(scar tissue) and/or

inflammation Inflammation (from la, wikt:en:inflammatio#Latin, inflammatio) is part of the complex biological response of body tissues to harmful stimuli, such as pathogens, damaged cells, or Irritation, irritants, and is a protective response involving im ...

.Merriam-Webster Medical Dictionary > bronchiolitis obliterans
Retrieved on August, 2010

Uses

PHMG was used in Russia to disinfect hospitals and from 2001 on, it was widely used in

South Korea South Korea, officially the Republic of Korea (ROK), is a country in East Asia, constituting the southern part of the Korea, Korean Peninsula and sharing a Korean Demilitarized Zone, land border with North Korea. Its western border is formed ...

as a disinfectant to prevent microbial contamination in household

humidifier A humidifier is a device, primarily an electrical appliance, that increases humidity (moisture) in a single room or an entire building. In the home, point-of-use humidifiers are commonly used to humidify a single room, while whole-house or furnac ...

s.Lee Hyun-jeong for the Korea Herald. April 24, 201
Oxy suspected of watering down report
/ref> PHMG was "originally marketed for cleaning a humidifier's water tank but instead used by the public as a water additive to suppress microbial growth."

South Korean lung disease outbreak and deaths

The pulmonary toxicity of PHMG was discovered due to an outbreak of severe lung disease in South Korea, detected in children in the spring of the years 2006 to 2011, and in adults in the spring of 2011; the mortality rate in children was 58%, while among adults, 53% died or required lung transplantation. Autopsies and epidemiological work, followed up by animal studies, led the South Korean CDC to identify PHMG used in humidifiers as the cause. It was banned in 2011, and new cases ceased occurring.

Reckitt Benckiser Reckitt Benckiser Group plc, trading as Reckitt, is a British multinational consumer goods company headquartered in Slough, England. It is a producer of health, hygiene and nutrition products. The company was formed in March 1999 by the merg ...

was one of the companies that sold this product in South Korea and it resisted taking responsibility until May 2016, when the Korean division chief apologized to victims and families in a press conference and offered compensation to the families of those who died to those who were injured; it was the first time the company had acknowledged that its products containing PHMG were harmful.

References

{{authority control Guanidines Antiseptics and disinfectants Organic polymers