3.3 Humans
A limited number of studies have considered the accumulation of pyrethroids in
human milk. In 2017, 206–258 million people were estimated to have contracted
malaria and 0.41 million died (94% in Africa and 67% children under 5 years) [57].
The World Health Organization (WHO) supports the use of specific pesticides for
malaria control. In tropical Africa, pyrethroids were used on mosquito nets and
as indoor sprays [58].
Pyrethroid exposure in a rural area at the south of Mozambique was assessed
using 22 breast milk samples from 2002 [59]. Indoor thatch samples were also
collected from walls to determine potential exposure. Permethrin and λ-cyhalothrin,
esfenvalerate, cypermethrin, tetramethrin and bifenthrin were found in 19 samples,
while cyfluthrin was detected in only 9 samples. Deltamethrin, phenothrin and
resmethrin were never detected. Individual concentrations went up to 36 pg/g lw
for bifenthrin; 160–230 pg/g lw for cypermethrin, esfenvalerate, tetramethrin,
cyfluthrin and permethrin; and 440 pg/g lw for λ-cyhalothrin. Total pyrethroid levels
were between 87 and 1,200 ng/g lw. The main contributor to the pyrethroid
profiles was λ-cyhalothrin (35%) followed by permethrin (21%) and cypermethrin,
esfenvalerate and tetramethrin (14%).
Pyrethroids had previously been found in human breast milk from Switzerland
with median total concentrations between 15 and 31 ng/g lw [60]. The difference to
the levels from Mozambique can be related to a more limited use for agricultural
and domestic applications in Switzerland [60].
Conversely, a mean value of 1,200 ng/g lw of permethrin and lower levels of
cypermethrin and cyfluthrin had been reported in samples from South Africa [61].
These pyrethroids were also detected in other samples from the same region at
14,500, 4,200 and 42,000 ng/l, respectively [9]. The authors suggested a domestic
source of contamination for the first group of samples and an agricultural source
for the latter. Converting these results according to their reported fat content of 4%,
total concentrations ranged from 110 to 1,050 ng/g lw, which is similar to the
milk samples from Mozambique.
The fact that mothers accumulate pyrethroids implies that they could be
transferred to their offspring through lactancy. Estimated daily intake (EDI) values
for the babies in Mozambique went from 0.12 μg/kg of body weight and per day
for cypermethrin to 3.4 μg/kg of body weight and per day for cyhalothrin [59].
The acceptable daily intake (ADI) values for individual pyrethroids are set between
10 and 50 μg/kg bw/day [62], which means that pyrethroid intake should not pose
a threat to the babies.
A bigger and more recent study included 56 human milk samples from Colombia,
Spain and Brazil, including urban and rural areas [10]. Pyrethroids occurred in all
the samples at concentrations from 1.45 to 24.2 ng/g lw in the three countries.
Their results were also similar to the ones reported for the Swiss samples [60].
Urban samples from Spain and Brazil showed a mean around 5 ng/g lw, and rural
samples from Brazil and Colombia had a mean value just above 9 ng/g lw.
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Ò. Aznar-Alemany and E. Eljarrat
A limited number of studies have considered the accumulation of pyrethroids in
human milk. In 2017, 206–258 million people were estimated to have contracted
malaria and 0.41 million died (94% in Africa and 67% children under 5 years) [57].
The World Health Organization (WHO) supports the use of specific pesticides for
malaria control. In tropical Africa, pyrethroids were used on mosquito nets and
as indoor sprays [58].
Pyrethroid exposure in a rural area at the south of Mozambique was assessed
using 22 breast milk samples from 2002 [59]. Indoor thatch samples were also
collected from walls to determine potential exposure. Permethrin and λ-cyhalothrin,
esfenvalerate, cypermethrin, tetramethrin and bifenthrin were found in 19 samples,
while cyfluthrin was detected in only 9 samples. Deltamethrin, phenothrin and
resmethrin were never detected. Individual concentrations went up to 36 pg/g lw
for bifenthrin; 160–230 pg/g lw for cypermethrin, esfenvalerate, tetramethrin,
cyfluthrin and permethrin; and 440 pg/g lw for λ-cyhalothrin. Total pyrethroid levels
were between 87 and 1,200 ng/g lw. The main contributor to the pyrethroid
profiles was λ-cyhalothrin (35%) followed by permethrin (21%) and cypermethrin,
esfenvalerate and tetramethrin (14%).
Pyrethroids had previously been found in human breast milk from Switzerland
with median total concentrations between 15 and 31 ng/g lw [60]. The difference to
the levels from Mozambique can be related to a more limited use for agricultural
and domestic applications in Switzerland [60].
Conversely, a mean value of 1,200 ng/g lw of permethrin and lower levels of
cypermethrin and cyfluthrin had been reported in samples from South Africa [61].
These pyrethroids were also detected in other samples from the same region at
14,500, 4,200 and 42,000 ng/l, respectively [9]. The authors suggested a domestic
source of contamination for the first group of samples and an agricultural source
for the latter. Converting these results according to their reported fat content of 4%,
total concentrations ranged from 110 to 1,050 ng/g lw, which is similar to the
milk samples from Mozambique.
The fact that mothers accumulate pyrethroids implies that they could be
transferred to their offspring through lactancy. Estimated daily intake (EDI) values
for the babies in Mozambique went from 0.12 μg/kg of body weight and per day
for cypermethrin to 3.4 μg/kg of body weight and per day for cyhalothrin [59].
The acceptable daily intake (ADI) values for individual pyrethroids are set between
10 and 50 μg/kg bw/day [62], which means that pyrethroid intake should not pose
a threat to the babies.
A bigger and more recent study included 56 human milk samples from Colombia,
Spain and Brazil, including urban and rural areas [10]. Pyrethroids occurred in all
the samples at concentrations from 1.45 to 24.2 ng/g lw in the three countries.
Their results were also similar to the ones reported for the Swiss samples [60].
Urban samples from Spain and Brazil showed a mean around 5 ng/g lw, and rural
samples from Brazil and Colombia had a mean value just above 9 ng/g lw.
214
Ò. Aznar-Alemany and E. Eljarrat