Cypermethrin, permethrin, λ-cyhalothrin and fenvalerate were detected in all or
almost all the samples. Cyfluthrin, fluvalinate, phenothrin and resmethrin were
never detected. Individual concentrations decreased from cypermethrin (up to
16.4 ng/g lw) through tetramethrin, λ-cyhalothrin, bifenthrin, permethrin, fenvalerate
to deltamethrin (up to 1.86 ng/g lw).
Pyrethroid profiles suggested usage of different pyrethroids in different areas.
For example, bifenthrin had a great contribution in the Brazilian samples, but
not so much in the others. Cypermethrin was the biggest contributor to the
Colombian profiles, which is consistent with the pesticide use in that country [10].
Finally, permethrin dominated the Spanish samples, which agrees with the results of
the aforementioned striped dolphin livers from southern Spain [8].
The authors reported no correlation between pyrethroid levels and the age
of the mother or between the domestic use of pesticides and levels in breast milk.
On the other hand, the contamination in milk decreased exponentially with parity
(number of children of a mother), supporting the hypothesis of maternal transfer of
pyrethroids. All samples presented EDI values below the ADI values. However,
cypermethrin was very close to its 50 μg/kg bw/day ADI with occasional EDI
values of 48.8 and 44.2 μg/kg bw/day for samples from 2003 to 2004, respectively.
Cypermethrin had been used to control dengue.
3.4 Isomer-Specific Accumulation
Pyrethroids have two or three chiral centres in their structures. This means that
they have two or four diastereomers and four or eight enantiomers. Many of
the works referenced in this chapter performed isomeric analysis with a chiral
chromatographic column after the corresponding quantitative analysis. The
enantiomeric factors (EF) for each enantiomeric pair were calculated dividing
the chromatographic area of the first eluting enantiomer by the sum of the areas
of both enantiomers [63]. A racemic mixture, containing equal amounts of each,
corresponds to EF ¼ 0.5. As type I pyrethroids present a cis and a trans enantiomeric
pairs, EF cis and EF trans are defined. Type II pyrethroids present two of each, defined
as EF cis1 , EF cis2 , EF trans1 and EF trans2 . Diastereoisomeric factors (R) were also
calculated [63]. R cis/trans represents the ratio between cis and trans isomers of
an individual pyrethroid; meaning cis1 + cis2 and trans1 + trans2 for type II
pyrethroids. R cis1/cis2 and R trans1/trans2 were also assessed for type II pyrethroids.
These factors can help determine isomer-specific accumulation or metabolization
in mammals. R values for esfenvalerate, permethrin and cypermethrin for calves,
juvenile and adult Franciscana dolphins were calculated [7]. While esfenvalerate
and cypermethrin showed no differences with age group (R esfen ¼ 0.48–0.67,
R cyp ¼ 0.28–0.49), some differences were reported for permethrin. The mean
R perm value in calves was 0.84, showing a higher contribution of the first isomer.
However, the mean R perm values for juveniles and adults were 0.60 and 0.69,
suggesting either a selective bioaccumulation of the trans isomer in the first years
Bioavailability and Bioaccumulation of Pyrethroid Insecticides in Wildlife and. . .
215
almost all the samples. Cyfluthrin, fluvalinate, phenothrin and resmethrin were
never detected. Individual concentrations decreased from cypermethrin (up to
16.4 ng/g lw) through tetramethrin, λ-cyhalothrin, bifenthrin, permethrin, fenvalerate
to deltamethrin (up to 1.86 ng/g lw).
Pyrethroid profiles suggested usage of different pyrethroids in different areas.
For example, bifenthrin had a great contribution in the Brazilian samples, but
not so much in the others. Cypermethrin was the biggest contributor to the
Colombian profiles, which is consistent with the pesticide use in that country [10].
Finally, permethrin dominated the Spanish samples, which agrees with the results of
the aforementioned striped dolphin livers from southern Spain [8].
The authors reported no correlation between pyrethroid levels and the age
of the mother or between the domestic use of pesticides and levels in breast milk.
On the other hand, the contamination in milk decreased exponentially with parity
(number of children of a mother), supporting the hypothesis of maternal transfer of
pyrethroids. All samples presented EDI values below the ADI values. However,
cypermethrin was very close to its 50 μg/kg bw/day ADI with occasional EDI
values of 48.8 and 44.2 μg/kg bw/day for samples from 2003 to 2004, respectively.
Cypermethrin had been used to control dengue.
3.4 Isomer-Specific Accumulation
Pyrethroids have two or three chiral centres in their structures. This means that
they have two or four diastereomers and four or eight enantiomers. Many of
the works referenced in this chapter performed isomeric analysis with a chiral
chromatographic column after the corresponding quantitative analysis. The
enantiomeric factors (EF) for each enantiomeric pair were calculated dividing
the chromatographic area of the first eluting enantiomer by the sum of the areas
of both enantiomers [63]. A racemic mixture, containing equal amounts of each,
corresponds to EF ¼ 0.5. As type I pyrethroids present a cis and a trans enantiomeric
pairs, EF cis and EF trans are defined. Type II pyrethroids present two of each, defined
as EF cis1 , EF cis2 , EF trans1 and EF trans2 . Diastereoisomeric factors (R) were also
calculated [63]. R cis/trans represents the ratio between cis and trans isomers of
an individual pyrethroid; meaning cis1 + cis2 and trans1 + trans2 for type II
pyrethroids. R cis1/cis2 and R trans1/trans2 were also assessed for type II pyrethroids.
These factors can help determine isomer-specific accumulation or metabolization
in mammals. R values for esfenvalerate, permethrin and cypermethrin for calves,
juvenile and adult Franciscana dolphins were calculated [7]. While esfenvalerate
and cypermethrin showed no differences with age group (R esfen ¼ 0.48–0.67,
R cyp ¼ 0.28–0.49), some differences were reported for permethrin. The mean
R perm value in calves was 0.84, showing a higher contribution of the first isomer.
However, the mean R perm values for juveniles and adults were 0.60 and 0.69,
suggesting either a selective bioaccumulation of the trans isomer in the first years
Bioavailability and Bioaccumulation of Pyrethroid Insecticides in Wildlife and. . .
215