Many of the cited works performed isomeric analysis to assess the isomer-specific
accumulation or metabolization in mammals. The Franciscana dolphins seemed
to either bioaccumulate trans-permethrin selectively in their first years of life
or metabolize cis isomer better after they reached sexual maturity [7]. An
enrichment on the trans isomer of permethrin was also observed in the samples of
human milk from Mozambique [59]. The isomeric data of Mediterranean striped
dolphins [8] showed no enantiomer-specific accumulation of tetramethrin. However,
enantiomer-specific accumulation of (1S,3S)-permethrin over (1R,3R)-permethrin
was suggested.
Almost all the samples of Iberian river fish showed a preference to bioaccumulate
the cis isomers of pyrethroids, with only tetramethrin opposing that trend [43].
The authors argued that this could mirror the environmental contamination
as commercial mixtures might be rich in trans-tetramethrin and a dominance of
cis-permethrin was also observed for the samples of Spanish human milk [10]
and the unhatched eggs from Doñana [53]. Isomer-selective bioaccumulation
depending on fish species was also hinted at in this study [43] and on the one on
farmed salmon [48].
The analysis of human milk samples from Brazil, Colombia and Spain
showed higher accumulation of the cis isomer for esfenvalerate and permethrin
and the contrary for cyfluthrin, cypermethrin and tetramethrin [10]. Cyfluthrin and
cypermethrin disagree with the cis-dominating trend of other studies, which might
imply that their trans isomers were selectively accumulated in human milk. The
human milk samples from Mozambique contradicted the cis-dominating trend
for permethrin, which might reflect a higher bioaccumulation of the trans isomer
or a better metabolization of cis-permethrin [59].
Analysing environmental samples from the areas where biological samples are
collected would allow more accurate observations regarding isomer selectivity.
Related to breast milk, lactation and gestation result in the maternal transfer
of contaminants [66, 67]. The maternal transfer of pyrethroids has been observed
using samples of breast milk and placenta from pregnant and lactating Franciscana
dolphins [7] and several tissues from mother-foetus pairs of Franciscana dolphins
and Guiana dolphins [70]. Foetuses showed a higher pyrethroid burden in blubber
than their mothers, but the contrary happened for muscle tissue. As pyrethroids are
also found in human milk, they must be transferred to lactating babies; however,
the EDI values reported by the corresponding studies for each pyrethroid were below
their corresponding ADI [10].
References
1. Barr DB, Olsson AO, Wong LY et al (2010) Urinary concentrations of metabolites of pyrethroid
insecticides in the general U.S. population: national health and nutrition examination survey
1999–2002. Environ Health Perspect 118:742–748. https://doi.org/10.1289/ehp.0901275
2. AERU (2007) PPDB: Pesticide Properties DataBase. Agriculture & Environment Research
Unit (University of Hertfordshire). http://sitem.herts.ac.uk/aeru/footprint/index2.htm [data de
consulta: November 2019]
Bioavailability and Bioaccumulation of Pyrethroid Insecticides in Wildlife and. . .
221
accumulation or metabolization in mammals. The Franciscana dolphins seemed
to either bioaccumulate trans-permethrin selectively in their first years of life
or metabolize cis isomer better after they reached sexual maturity [7]. An
enrichment on the trans isomer of permethrin was also observed in the samples of
human milk from Mozambique [59]. The isomeric data of Mediterranean striped
dolphins [8] showed no enantiomer-specific accumulation of tetramethrin. However,
enantiomer-specific accumulation of (1S,3S)-permethrin over (1R,3R)-permethrin
was suggested.
Almost all the samples of Iberian river fish showed a preference to bioaccumulate
the cis isomers of pyrethroids, with only tetramethrin opposing that trend [43].
The authors argued that this could mirror the environmental contamination
as commercial mixtures might be rich in trans-tetramethrin and a dominance of
cis-permethrin was also observed for the samples of Spanish human milk [10]
and the unhatched eggs from Doñana [53]. Isomer-selective bioaccumulation
depending on fish species was also hinted at in this study [43] and on the one on
farmed salmon [48].
The analysis of human milk samples from Brazil, Colombia and Spain
showed higher accumulation of the cis isomer for esfenvalerate and permethrin
and the contrary for cyfluthrin, cypermethrin and tetramethrin [10]. Cyfluthrin and
cypermethrin disagree with the cis-dominating trend of other studies, which might
imply that their trans isomers were selectively accumulated in human milk. The
human milk samples from Mozambique contradicted the cis-dominating trend
for permethrin, which might reflect a higher bioaccumulation of the trans isomer
or a better metabolization of cis-permethrin [59].
Analysing environmental samples from the areas where biological samples are
collected would allow more accurate observations regarding isomer selectivity.
Related to breast milk, lactation and gestation result in the maternal transfer
of contaminants [66, 67]. The maternal transfer of pyrethroids has been observed
using samples of breast milk and placenta from pregnant and lactating Franciscana
dolphins [7] and several tissues from mother-foetus pairs of Franciscana dolphins
and Guiana dolphins [70]. Foetuses showed a higher pyrethroid burden in blubber
than their mothers, but the contrary happened for muscle tissue. As pyrethroids are
also found in human milk, they must be transferred to lactating babies; however,
the EDI values reported by the corresponding studies for each pyrethroid were below
their corresponding ADI [10].
References
1. Barr DB, Olsson AO, Wong LY et al (2010) Urinary concentrations of metabolites of pyrethroid
insecticides in the general U.S. population: national health and nutrition examination survey
1999–2002. Environ Health Perspect 118:742–748. https://doi.org/10.1289/ehp.0901275
2. AERU (2007) PPDB: Pesticide Properties DataBase. Agriculture & Environment Research
Unit (University of Hertfordshire). http://sitem.herts.ac.uk/aeru/footprint/index2.htm [data de
consulta: November 2019]
Bioavailability and Bioaccumulation of Pyrethroid Insecticides in Wildlife and. . .
221