mixture, the second pair differed from this behaviour with a potential selective
accumulation of (1S,3S,αR)-cypermethrin (EF cis2 < 0.35) as the commercial
pesticides had racemic mixtures.
While R cis/trans values for tetramethrin and cypermethrin were similar for
human milk and the commercial pesticides, suggesting no specific bioaccumulation,
cis-permethrin seemed to be selectively accumulated in human samples [63].
A great preference for the second cis isomer of cypermethrin eluted was also
observed when compared to the commercial pesticides.
4 Maternal Transfer
Maternal transfer occurs during gestation and lactation [66, 67]. Therefore, the
exposition of pregnant individuals to contaminants might threaten their offspring,
increasing their susceptibility to disease in adulthood [68, 69].
Samples of breast milk and placenta from three pregnant and lactating dead
Franciscana dolphins (Pontoporia blainvillei) were collected in Brazil and analysed
in a first attempt to study maternal transfer [7]. The placenta provides an indication
of prenatal exposure to pyrethroids, while breast milk indicates the postnatal
transfer to calves. Pyrethroids were found in both milk (2.5–4.8 ng/g lw) and
placenta (331–1812 ng/g lw), suggesting the maternal transfer of pyrethroids by
both gestational and lactation pathways.
The same authors added data to the literature with samples of several tissues from
five mother-foetus pairs of Franciscana dolphins and from three mother-foetus pairs
of Guiana dolphins (Sotalia guianensis) [70]. Muscle and blubber from mother
and foetus were taken from both species, as well as placenta, umbilical cord and
milk from Franciscana dolphins.
Pyrethroids were found in all the samples. Foetus-to-mother ratios (f/m) of total
pyrethroid concentrations in Franciscana dolphins were 1.43, 2.67, 4.13 and 19.5 in
blubber and 0.28 and 30 in muscle. A f/m value higher than 1 indicated higher
pyrethroid burden on the foetus than their mother. A higher bioaccumulation
in foetuses than mothers had already been observed for hexachlorobenzene in
long-finned pilot whales (Globicephala melas) from Australia and in beluga
whales (Delphinapterus leucas) from Alaska [71, 72]. A tendency to transfer
low-chlorinated contaminants and with lower log K ow from cetacean mothers to
foetuses had also been reported [68, 71]. Accordingly, the predominant pyrethroids
in foetal blubber of the Franciscana dolphins were two-chlorinated cypermethrin and
permethrin (log K ow 6.6 and 6.5), suggesting a tendency similar to low-chlorinated
pesticides [70].
The f/m values of total pyrethroid concentrations in Guiana dolphins were 0.42,
1.39 and 1.47 in blubber and 0.09, 0.12 and 0.35 in muscle. The two different tissues
showed different patterns, with a higher burden in the foetuses’ blubber, but higher
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Ò. Aznar-Alemany and E. Eljarrat
accumulation of (1S,3S,αR)-cypermethrin (EF cis2 < 0.35) as the commercial
pesticides had racemic mixtures.
While R cis/trans values for tetramethrin and cypermethrin were similar for
human milk and the commercial pesticides, suggesting no specific bioaccumulation,
cis-permethrin seemed to be selectively accumulated in human samples [63].
A great preference for the second cis isomer of cypermethrin eluted was also
observed when compared to the commercial pesticides.
4 Maternal Transfer
Maternal transfer occurs during gestation and lactation [66, 67]. Therefore, the
exposition of pregnant individuals to contaminants might threaten their offspring,
increasing their susceptibility to disease in adulthood [68, 69].
Samples of breast milk and placenta from three pregnant and lactating dead
Franciscana dolphins (Pontoporia blainvillei) were collected in Brazil and analysed
in a first attempt to study maternal transfer [7]. The placenta provides an indication
of prenatal exposure to pyrethroids, while breast milk indicates the postnatal
transfer to calves. Pyrethroids were found in both milk (2.5–4.8 ng/g lw) and
placenta (331–1812 ng/g lw), suggesting the maternal transfer of pyrethroids by
both gestational and lactation pathways.
The same authors added data to the literature with samples of several tissues from
five mother-foetus pairs of Franciscana dolphins and from three mother-foetus pairs
of Guiana dolphins (Sotalia guianensis) [70]. Muscle and blubber from mother
and foetus were taken from both species, as well as placenta, umbilical cord and
milk from Franciscana dolphins.
Pyrethroids were found in all the samples. Foetus-to-mother ratios (f/m) of total
pyrethroid concentrations in Franciscana dolphins were 1.43, 2.67, 4.13 and 19.5 in
blubber and 0.28 and 30 in muscle. A f/m value higher than 1 indicated higher
pyrethroid burden on the foetus than their mother. A higher bioaccumulation
in foetuses than mothers had already been observed for hexachlorobenzene in
long-finned pilot whales (Globicephala melas) from Australia and in beluga
whales (Delphinapterus leucas) from Alaska [71, 72]. A tendency to transfer
low-chlorinated contaminants and with lower log K ow from cetacean mothers to
foetuses had also been reported [68, 71]. Accordingly, the predominant pyrethroids
in foetal blubber of the Franciscana dolphins were two-chlorinated cypermethrin and
permethrin (log K ow 6.6 and 6.5), suggesting a tendency similar to low-chlorinated
pesticides [70].
The f/m values of total pyrethroid concentrations in Guiana dolphins were 0.42,
1.39 and 1.47 in blubber and 0.09, 0.12 and 0.35 in muscle. The two different tissues
showed different patterns, with a higher burden in the foetuses’ blubber, but higher
218
Ò. Aznar-Alemany and E. Eljarrat