The EN 1656 is a phase 2 step 1 suspension test used for anti-bacterial activity in the veterinary area. The EN 1656 is usually the first test you would do on a veterinary product much like the EN 1276. This is required for all biocides that are going to be sold into the veterinary market. If the product is going to be sold into other markets, then there are the EN 1276 and the EN 13727 which may be more appropriate. As the EN 1656 is a phase 2 step 1 test for bacteria it is similar to both the EN 1276 and the EN 13727 and similar results can often be expected.
The EN 1656 is a suspension test which means it is carried out in a suspension of test organism, interfering substance and test product. The interfering substance and the organism make up 20% of this mix so even ready to use product are diluted to 80% during the testing. If the product is prediluted before the testing starts, we increase the percentage of product by 1.25 to account for the 80% dilution.
Although there are named obligatory organisms in the EN 1656 additional bacteria can be added to support additional claims. This regularly includes organisms specific to the area of veterinary that the product is going to be used in. Many people choose to add specific animal disease causing bacteria. Virtually any bacteria can be added the to EN 1656.
For BPR submission the EN 1656 is essential, and 3 concentrations must be tested. These have to include the final usage concentration, a concentration that fails the test and then any other. Most commonly people opt for the end concentration, 50% of that and the 10% or 1% of that.
Although the standard has specific requirements as outlines in the table certain other establishments may have more rigorous requirements. For example, some veterinary practices may want a certain temperature or time depending on the end use of the product. This should be taken into consideration before deciding on the conditions.