ASTM F1671 / F1671M – 13. Standard Test Method for Resistance of Materials Used in Protective Clothing to Penetration by Blood-Borne Pathogens Using Phi-X174 Bacteriophage Penetration as a Test System. ISO 16604: 2004. Clothing for protection against contact with blood and body fluids -- Determination of resistance of protective clothing materials to penetration by blood-borne pathogens - Test method using Phi-X 174 bacteriophage.
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Health professionals who treat and care for patients can be exposed to biological fluids that can transmit diseases. These diseases can be caused by a wide variety of microorganisms and can pose a significant risk to health and life. This situation is especially important in the case of blood-borne viruses, such as the hepatitis B virus (HBV), the hepatitis C virus (HCV) or the human immunodeficiency virus (HIV). To protect themselves from infectious agents transmitted by blood, health personnel should wear protective clothing made of materials that prevent microbes or viruses from passing through. These protective garments can be, for example, gloves, aprons, masks, hoods, or boots, among others.
The method described in these standards, evaluates the effectiveness of materials used in the manufacture of protective garments against bloodborne pathogens using a surrogate virus suspended in a liquid, simulating the spontaneous contact conditions in a sanitary environment. The material used in the protective garment will pass or fail in the test, depending on whether it resists penetration (is not traversed) or allows it (to be traversed). This method is not effective for testing protective clothing materials that are internally coated by a thick coating that can absorb the liquid containing the test virus. This method is specifically defined for a penetration model of hepatitis B virus, hepatitis C virus and human immunodeficiency virus, and it is considered by extension that if it resists penetration by these viruses, it will also resist penetration by larger microorganisms like bacteria.
To perform the method, samples of the materials are exposed to a nutrient broth containing the bacteriophage virus Phi-X174, as a virus surrogated by its characteristics similar in size to the hepatitis C virus, and by extension to the hepatitis B virus and of human immunodeficiency virus (these viruses are not used because of their difficulty to be cultured in laboratories). The exposure is carried out for a specified time and under a selected pressure. The pressure used under normal conditions corresponds to 13.8 kPa, but it can be chosen up to 345 kPa, as this is the pressure that can sometimes be reached in certain situations. The possible alterations of the protective material due to physical, chemical or thermal effects should be taken into account, since in this case they would negatively influence the behavior of the material, so that in case it can occur, the tests should be carried out before exposures to such material, physical, chemical or thermal conditions that may deteriorate it. The method is evaluated by two procedures: a) visual observation of the possible penetration of liquid from the suspension through the material, and b) by detecting the virus on the opposite surface to which the material subject to the study was exposed to the suspension viral, although the presence of fluid on the opposite side to the exposure had not been observed. Any visual or virological evidence of penetration will indicate the inability of the material to resist penetration.
The test is performed in a chamber of two compartments, separated by the material evaluated. In one of the 60 mL compartments capacity the viral suspension of exposure is introduced, containing the bacteriophage Phi-X174 and in the opposite compartment the appearance of liquid or the presence of the virus is detected. The pieces of the evaluated materials are recommended to have about 75 mm on each side, of which a 57 mm diameter circle is exposed. The manufacturer must indicate the possibility that the material under test can be altered by thermal treatment (wet sterilization), so as not to do so in the event that it can be altered. In case a non-sterile material is used, the test will include the corresponding controls to exclude the presence of the bacteriophage in the materials evaluated. The test includes a positive control consisting of a membrane with a pore slightly greater than the diameter of the bacteriophage (0.027 μm), which will allow the virus to pass through, as well as a negative control, which will be processed in the same conditions. Samples of the material under test are conditioned for at least 24 hours at a temperature of 21 ± 5°C and a humidity of 30 to 80%. The suspension used to prepare the suspension of bacteriophage use contains 3.0 to 7.0 x 1010 PFU/mL and is used at a concentration of 1.0 x 108 PFU/mL. The test is carried out observing the penetration of liquid without pressure for 5 minutes, followed by 1 minute at the indicated pressure (1.38-kPa, or higher if this has been chosen), performing the observation