BfR Annual Report 2015

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BfR | Annual Report 2015 74
Plant protection products residues:
processing factors must be taken into
account
Even when authorised plant protection products are
used in a proper manner and for the intended purpose to
protect plants against harmful organisms, it is still possi-
ble that residues may be present in the harvested crops
and in the food and feed therefrom. To ensure that these
residues do not pose a risk to the health of consumers,
the BfR draws up proposals for maximum residue levels.
In the European Union, maximum admissible residue lev-
els of pesticides are only established for raw agricultural
products (Annexes to Regulation (EC) No. 396/2005).
However, many of these products are not eaten raw but
after having been processed, and some of the process-
ing operations – such as milling of wheat grain or the
production of apple juice – can alter the chemical nature
and level of residues. Both increases and reductions in
residue levels may be observed in the various processed
fractions; for example, in bran and flour from wheat grain
or in pomace and juice in the case of apple fruit. The
ratio of residue concentration in the processed product
relative to that in the starting material is called “process-
ing factor”. The magnitude of this factor depends not
only on the type of processing method but also on the
physico-chemical properties of the active substance.
Processing factors are not only of importance for assess-
ment of health risks that can result from pesticide resi-
dues in processed food but also serve as an important
source of information for official food control activities.
Even if the statutory maximum residue levels are only
stipulated for raw products, they nevertheless apply to
the processed products made from these raw products
– by taking into account the processing factors. Only this
information allows for judgement of whether a sampled
processed product complies with the legal requirements.
The EU Regulation 396/2005 foresees the provision of
processing factors in a separate annex, but this annex
has not yet been established.
In the framework of the approval of pesticidal active
substances and the authorisation of plant protection
products, applicants are required to submit processing
studies to the regulatory authorities. In these studies,
processing factors are derived from processes simulat-
ed in the laboratory. In order to make the information in
these studies available also to interested public, the BfR
has evaluated the reliability of all available studies based
on strict criteria and published ca. 6,300 derived factors
for 193 active substances in a database on the BfR web-
site. Alongside the derived factors, the website also pro-
vides transparent information on how the BfR performed
its “quality check” for every individual study by outlining
all the key study parameters that determine the reliabil-
ity of the findings. These quality criteria include i. a. the
suitability of the analytical method used and the proved
storage stability of the samples. Dependent on the relia-
bility of the recorded results, the studies are divided into
three categories. In addition, some contents of the test-
ing guidelines used for the studies are critically reviewed
in the light of the experience gained, and suggestions
are made for improvements. One of these suggestions is
that the simulated processing methods should be stand-
ardised to a greater extent and that the terminology used
for processing fractions should be harmonised. A total
of 34 of such standard process diagrams have already
been proposed.
i More information (in German) on processing factors:
Container fumigation and residues of
volatile toxins in products
In the international freight transport sector, gaseous pesti-
cides are used to protect vulnerable goods. The transport-
ed goods are mostly treated directly in the container and
exposed against the fumigants between 24 and 72 hours
in general. However, illegal fumigation and inadequate
ventilation can lead to far longer exposure. The gaseous
biocides used for this purpose include substances such
as methyl bromide, hydrogen phosphide (“phosphine”),
sulphuryl fluoride or 1,2-dichloroethane, all of which own
an extremely high toxicity for both, harmful organisms (so-
called “pests”) and humans. There are reports of occa-
sional poisoning accidents due to insufficient ventilation,
involving employees in ports or import companies. As the
outgassing characteristics of the fumigants have not been
Gaseous pesticides are often used in containers to protect
vulnerable goods.