[107]. Therefore, food samples that present different profiles of stereoselectivity,
which may include the most toxic and persistent isomers, should not be compared to
reference values based on racemic formulations, since they are not equivalent. In
this case, variation at enantiomeric levels found in food samples can result in an
imprecise comparison between their contamination profile and the established limits
for quality and food safety.
5 Conclusions and Trends
The desired effects attributed to pyrethroids are related to specific enantiomers. In
this sense, studies have shown higher acute toxicity of active insecticide enantiomers
to nontarget organisms, such as earthworms, zooplankton, fish and tadpoles. However, adverse effects, such as endocrine disruption and cytotoxicity, determined
through in vivo and in vitro assays with fish and mammals have been reported in
studies considering enantiomers with low or no insecticidal action.
Although previous studies point to a higher occurrence of cis-isomers in biological systems, considerable research remains to be performed on the persistence of
pyrethroid enantiomers, their effects on sensitive organisms and the possible impacts
on complex environmental functions, such as the degradation of pollutants in soils
and at the base of the food chain in aquatic environments.
A possible action for minimizing environmental enantiomer overloads and the
expected impacts on environmental and human health was proposed in Regulation
(EC) No 1107/2009 from the European Community, which suggests the substitution
of agrochemicals applied to crops containing a significant proportion of non-specific
isomers [99]. In this direction, future policies aimed at sustainable innovation should
be considered for companies that propose enantiomerically pure, safe and less
persistent commercial formulations.
Although the persistence of pyrethroids is important for the maintenance of their
insecticidal action for an extended period, which can vary widely (from hours to
months) according to the compounds and the environmental conditions [8], the use
of less persistent formulations in domestic environments should also be considered.
However, studies are required to assess potential acute and chronic toxicity in a
scenario of increased human exposure to pyrethroid metabolites and their degradation products.
With regard to feeding safety, studies are required to address the stereoselective
behaviour of pyrethroids in food samples and the consequent dietary exposure to
more persistent and more toxic isomers. This approach should include the
established limits for food quality, as well as the behaviour and stability of these
chiral compounds during the preparation and cooking steps up to the industrial food
processing.
Stereoselectivity and Environmental Behaviour of Pyrethroids
169
which may include the most toxic and persistent isomers, should not be compared to
reference values based on racemic formulations, since they are not equivalent. In
this case, variation at enantiomeric levels found in food samples can result in an
imprecise comparison between their contamination profile and the established limits
for quality and food safety.
5 Conclusions and Trends
The desired effects attributed to pyrethroids are related to specific enantiomers. In
this sense, studies have shown higher acute toxicity of active insecticide enantiomers
to nontarget organisms, such as earthworms, zooplankton, fish and tadpoles. However, adverse effects, such as endocrine disruption and cytotoxicity, determined
through in vivo and in vitro assays with fish and mammals have been reported in
studies considering enantiomers with low or no insecticidal action.
Although previous studies point to a higher occurrence of cis-isomers in biological systems, considerable research remains to be performed on the persistence of
pyrethroid enantiomers, their effects on sensitive organisms and the possible impacts
on complex environmental functions, such as the degradation of pollutants in soils
and at the base of the food chain in aquatic environments.
A possible action for minimizing environmental enantiomer overloads and the
expected impacts on environmental and human health was proposed in Regulation
(EC) No 1107/2009 from the European Community, which suggests the substitution
of agrochemicals applied to crops containing a significant proportion of non-specific
isomers [99]. In this direction, future policies aimed at sustainable innovation should
be considered for companies that propose enantiomerically pure, safe and less
persistent commercial formulations.
Although the persistence of pyrethroids is important for the maintenance of their
insecticidal action for an extended period, which can vary widely (from hours to
months) according to the compounds and the environmental conditions [8], the use
of less persistent formulations in domestic environments should also be considered.
However, studies are required to assess potential acute and chronic toxicity in a
scenario of increased human exposure to pyrethroid metabolites and their degradation products.
With regard to feeding safety, studies are required to address the stereoselective
behaviour of pyrethroids in food samples and the consequent dietary exposure to
more persistent and more toxic isomers. This approach should include the
established limits for food quality, as well as the behaviour and stability of these
chiral compounds during the preparation and cooking steps up to the industrial food
processing.
Stereoselectivity and Environmental Behaviour of Pyrethroids
169