What is a key limitation to biocides?

A key limitation to biocides is that they can kill some microorganisms, which may inadvertently create a safe haven for others. This phenomenon occurs because when certain pathogens or microorganisms are eliminated, it can allow surviving species, which may be more resistant to biocide treatment, to proliferate. This can lead to a shift in the microbial population, potentially resulting in more harmful organisms dominating the environment, thus undermining the initial purpose of using biocides for microbial control.

While the other options present relevant points, they do not capture this specific limitation of biocides as effectively. The requirement for oversight as per FIFRA is an important regulatory consideration but does not address the effectiveness and ecological balance concerns related to microbial populations. Similarly, needing to be used on porous surfaces or generating low levels of ozone are valid factors, though they do not reflect the broader implication of biocide use on microbial ecology.