IJCA - Volume 3 - Flipbook - Page 10
8
The International Journal of Conformity Assessment
As sampling design and execution are not addressed
by the ISO/IEC 17025 quality standard, laboratories
and conformity assessment bodies must therefore
evaluate sampling protocols under other—more
general—quality management system standards.
Because sampling is not a core competency
of all laboratories, much of today’s food safety
testing is performed on samples collected in an
uncontrolled manner. If steps are not taken to guard
the representativity of a sample, the results may be
skewed or useless.
TRACEABILITY
In a similar fashion, if sample traceability is not
maintained from the original lot through the chain
of custody to the laboratory and within an analytical
procedure, results cannot be guaranteed to represent
the lot of interest. When lots are mixed, for example,
residues may be diluted, and limits of quantitation
may not be met (when evaluated against the original
lots) due to the dilution. If a critical result is found, it
cannot be determined without further testing which
of the mixed lots may be un昀椀t for market.
CONTAMINATION
While it is di昀케cult to prevent contamination 100
percent of the time, many practical steps can be
taken to avoid inadvertently invalidating a collected
sample: proper use of personal protective equipment
and hygiene, correct execution of validated protocols,
use of materials previously veri昀椀ed to be free from
background presence of analytes, and proper training
of staff throughout the chain of custody.
Common Critical Failures Affecting
Impact or Use of Information
DELAYS IN TIME
It is vital to ensure that analytical results are reported
before pivotal decisions are taken. For example, if
a load of perishable goods must be o昀툀oaded by
08:00 but the results are not ready until 12:00, the
buyer loses the opportunity to evaluate results before
accepting the load. Or, if meta-control samples are
collected at the point-of-sale and microbiological
pathogens are detected, the information may arrive
too late to prevent consumers from ingesting these
foodborne pathogens.
ANALYTICAL ERRORS
It is possible for errors to occur even when
laboratories are accredited under ISO/IEC 17025,
participate in regular interlaboratory tests, use
validated analytical procedures, and maintain
appropriate quality controls. In such cases, results
may be entirely or partially invalidated simply due to
laboratory error. Storing counter samples may provide
options for remedying such mistakes, but counter
sample results can only be used for risk prevention
when the decision time frames are su昀케ciently wide.
FAILURE IN COMPETENCE
Compliance is not always straightforward in food
safety, as regulations may not always be clear in
their intent or technical details, and regulators may
differ from published texts in their enforcement
approaches. Even if the integrity of a sample is
maintained and analytical work is appropriate, incorrect
compliance evaluations and misguided decisions can
result from out-of-date information, inadequate breadth
or depth of knowledge, or a lack of familiarity with
changes in the legal and regulatory landscape.
Common Critical Failures Affecting
Interpretability
INCORRECT SCOPE OF TESTING
Appropriately de昀椀ning the scope for a given test is
as important as performing the test correctly. It is
a common occurrence that residues in food remain
undiscovered simply because they are not tested.
However, not knowing that a critical residue is present
does not absolve those involved in food trade of their
responsibility towards the consumer.
Here’s a speci昀椀c example: When a broad-spectrum
multiresidue pesticide analysis does not include
well-known metabolites of toxicological and
regulatory relevance, decision-makers may be misled
by interpreting “clean” reports as truly residue-free.
When one is unsure of scope, consulting a competent
subject matter expert for risk assessment is highly
recommended.
INADEQUATE LOQs
Similarly, relevant low quantities of residues may
not be detected or reported if appropriate Limits of
Quantitation (LOQs) are not met in quality controls or
Reporting Limits (RLs) are set unjusti昀椀ably high. It is
not uncommon for testing scopes to be broad enough
to cover the breadth of testing needs but fail to
reach the rigorous LOQs required to make legitimate
compliance evaluations.
LACKING ACCREDITATION OR VALIDATION
Ensuring proper laboratory method validation prior
to reporting 昀椀ndings is central to the reliability of test
results. Here, conformity assessment bodies play
a vital role in verifying that these method validation
