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ARS Home » Plains Area » Lincoln, Nebraska » Agroecosystem Management Research » Research » Publications at this Location » Publication #144858
Title: CHLORINE INACTIVATION OF ADENOVIRUS TYPE 40 AND FELINE CALICIVIRUS

Author
item THURSTON ENRIQUEZ, JEANETTE
item HAAS, CHARLES - PHILADELPHIA PA
item JACANGELO, JOSEPH - LOVETTSVILLE VA
item GERBA, CHARLES - TUCSON AZ

Submitted to: Applied and Environmental Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/1/2003
Publication Date: 11/1/2003
Citation: THURSTON ENRIQUEZ, J.A., HAAS, C.N., JACANGELO, J., GERBA, C. 2003. CHLORINE INACTIVATION OF ADENOVIRUS TYPE 40 AND FELINE CALICIVIRUS. JOURNAL OF APPLIED & ENVIRONMENTAL MICROBIOLOGY. 69:3979-3985.

Interpretive Summary: Chlorine is the most widely used drinking water disinfectant in the United States and disinfection is a critical barrier to viral pathogens due to their small size. Information available for determining adequate chlorine concentrations and contact times for viral inactivation in water are based on experiments conducted with one or a few dispersed enteric viruses, commonly poliovirus type 1 (PV-1) and other enteroviruses, that are suspended in buffered disinfectant demand free (BDF) water. However, enteric viral pathogens are shed in fecal matter in a clumped or aggregated form, water is not buffered or free of substances that consume disinfectants, and information regarding the effectiveness of drinking water disinfectants for inactivation of viruses recently identified as potential human health threats (emerging viruses) in drinking water is lacking. This study assessed the inactivation of a poliovirus type 1 (PV-1) and emerging enteric viruses, adenovirus type 40 (AD40) and feline calicivirus (FCV), by chlorine in both the dispersed (single particle) and aggregated states. FCV was used as a surrogate for the human caliciviruses since it is closely related based on nucleic acid organization and capsid architecture and can be assayed by mammalian cell culture. Since chlorine disinfection is affected by pH and temperature, experiments were conducted at high and low pH and temperatures. Viral inactivation was generally higher at low pH and high temperature conditions compared to high pH and low temperature conditions. The order of sensitivity of the studied viruses to chlorine is: FCV (most sensitive) >AD40>PV-1. The United States Environmental Protection Agency (USEPA) published a manual that guides water utility operators on the appropriate Ct, disinfectant concentration multiplied by the contact time, values for adequate inactivation of viruses. For experiments carried out with dispersed viruses, Ct values were below the suggested USEPA Ct values, however, experiments conducted with aggregated viruses and those suspended in treated groundwater were higher. Considering the state of viruses in water is most likely aggregated and associated with organic or inorganic matter, reevaluation of USEPA Guidance Manual Ct values is necessary since they would not be useful for ensuring inactivation of viruses in these states. According to commonly used free chlorine concentrations (1 mg/l) and contact times (237 min) applied for drinking water treatment in the United States, however, AD40, FCV, and PV-1 dispersed or aggregated particles would be sufficiently inactivated.

Technical Abstract: Ct, chlorine concentration multiplied by the contact time, values were determined for chlorine inactivation experiments carried out with chloroform extracted (dispersed) and non-chloroform extracted (aggregated) feline calicivirus (FCV), adenovirus type 40 (AD40) and polio virus type 1 (PV-1). Experiments were carried out with high and low pH and temperature conditions. Ct values, concentration of disinfectant multiplied by contact time of disinfectant and virus, were calculated directly from bench-scale chlorine inactivation experiments and from application of the Efficiency Factor Hom (EFH) model. For each experimental condition, Ct values were generally higher at pH 8 than pH 6, at 5 oC compared to 15 oC, and for AD40 compared to FCV. FCV and AD40 were more sensitive to free chlorine compared to PV-1. Cts for aggregated FCV and PV-1 experiments were 31 and 2.8 orders of magnitude higher than those calculated from experiments carried out with dispersed virus. Cts for 2 log inactivation of dispersed FCV and AD40 in treated groundwater at 15 oC were 1.2 and 15.1 times greater than buffered demand free water experiments at 5oC. Ct values listed in the United States Environmental Protection Agency (USEPA) Guidance Manual were close to, or lower than Ct values generated for AD40, FCV, and PV-1 experiments conducted with aggregated viruses and treated groundwater. Since the state of viruses in water is most likely aggregated and associated with organic or inorganic matter, reevaluation of USEPA Guidance Manual Ct values are necessary since they would not be useful for ensuring inactivation of viruses in these states. AD40, FCV, and PV-1 particles would be inactivated by commonly used free chlorine concentrations and contact times applied for drinking water treatment in the United States.