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Laundry Additives - Residual Self-Sanitization
DIS/TSS-14 July 29, 1981
Efficacy Data Requirements
Laundry Additives – Residual Self-Sanitization
The following requirements apply to products which bear claims to provide
residual self-sanitizing activity (i.e., significant reduction in numbers
of infectious microorganisms which may contaminate the items) on treated
fabrics when used in automatic or manual washing machine operations, usually
in the final rinse. Label claims for residual antimicrobial activity on
laundered materials or articles can only be considered in those situations
when such materials are likely to become and remain wet (for example,
diapers, and bed linens of incontinent persons) under normal conditions
of use and storage between launderings.
(a) Laundry operations. A clear distinction should be made on
the label between products recommended for household and coin-operated
laundering and products represented as commercial-industrial-institutional
laundry additives. The water to fabric ratio in home or coin-operated
machines is about 10:1 (w/w), whereas in industrial laundering operations
the ratio is about 5:1. The effectiveness of products may be significantly
altered by these differences; thus, demonstrated efficacy in one system
may not be extrapolated to the other. In addition, directions for use
of household laundering products may require different dosages for front-loading
automatics (e.g., 8-10 gallon water capacity) and top-loading automatics
and wringer-type washers (e.g., 12-15 gallon water capacity). Product
dosages, in this instance, should be specified in household measurements.
Dosage instructions for industrial laundering may be based on pounds of
dry fabric.
The directions for use of laundry additives should specify the machine
cycle in which the product is to be added, water level, temperature range,
and treatment time. Compatibility of the treatment with other common additives
(e.g., soaps, detergents, bleach, starch, bluing, sours, fabric softeners)
should be determined in testing an addressed in labeling, when applicable.
(b) Test standard. A suggested protocol published by Petrocci
and Clarke (J. AOAC 52:836-842) is acceptable for treating the fabric.
The basic elements outlined in the protocol of the "Quantitative
Procedure" of the American Association of Textile Chemists and Colorists
(AATCC) Test Method 100-1974 employing Staphylococcus aureus (ATCC 6538)
and Klebsiella pneumoniae (ATCC 4352) are acceptable for evaluating the
residual antimicrobial activity. However, 3 samples, representing 3 different
product batches must be tested, and the following modifications to the
method must be incorporated:
(1) Use a sufficient number of swatches placed exactly on top of each
other so that they completely absorb 1 ml of inoculum which is prepared
to contain at least 107 microorganisms/ml.
(2) The number of swatches used per jar must be reported.
(3) Incubation must be at 20-21 C (68-70 F).
(4) Quantitative bacteriological assays should be performed at the
following time intervals: 0, 30 min., 1-hr, 3-hr, 6-hr, and 24-hr. Consideration
could be given to fewer or different time intervals, depending on the
label claims, on a case-by-case basis.
(c) Performance standard. For residual self-sanitizing claims
against pathogenic microorganisms, the reduction of each test microorganism
must be at least 99.9% over the "0-time" control and the parallel
untreated inoculated control.
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