Food micro geek Don Schaffner of Rutgers University responds in a point-counterpoint style discussion of antibacterials in soap and effectiveness.

According to the story, a new study published in the Journal of Antimicrobial Chemotherapy found that antibacterial handwash is no more effective than plain soap at killing bacteria.

In recent years numerous products have appeared on the shelves claiming they were effective in killing 99.9 per cent of all germs.

But Korea University scientists investigated the effect of triclosan, the most commonly used active antiseptic ingredient in soap, in everyday conditions on bacteria such as MRSA, salmonella and listeria.

In recent years numerous products have appeared on the shelves claiming they were effective in killing 99.9 per cent of all germs. That’s actually a regulated label claim.  And it’s not “99.9 per cent of all germs.”  It’s 99.9 percent (3 log reduction for the math nerds) of certain regulatory-specified organisms under specified test conditions.

One central key weakness of the study is that authors state in their methods, “Antibacterial soap had the same formulation as plain soap except that it contained 0.3% triclosan.” While this might seem to be a good idea from the science perspective, it turns out that soap formulation is a tricky business. For antimicrobials to be optimally effective, the formulation might need to be adjusted. You can’t just throw sh*t in at ‘the maximum allowed by law’ and expect it to work.