Failure of the public health testing program for ballast water treatment systems

[Display omitted] •Ballast water treatment systems are tested and certified to protect public health.•We compared 10years of microbial test data against a minimum requirement for validity.•95% of tests were invalid.•In 62% of tests, target microbes in controls were below detection limits.•Treatment systems must be tested with concentrations found in contaminated waters. Since 2004, an international testing program has certified 53 shipboard treatment systems as meeting ballast water discharge standards, including limits on certain microbes to prevent the spread of human pathogens. We determined how frequently certification tests failed a minimum requirement for a meaningful evaluation, that the concentration of microbes in the untreated (control) discharge must exceed the regulatory limit for treated discharges. In 95% of cases where the result was accepted as evidence that the treatment system reduced microbes to below the regulatory limit, the discharge met the limit even without treatment. This shows that the certification program for ballast water treatment systems is dysfunctional in protecting human health. In nearly all cases, the treatment systems would have equally well “passed” these tests even if they had never been turned on. Protocols must require minimum concentrations of targeted microbes in test waters, reflecting the upper range of concentrations in waters where ships operate.