pyrethroids are widely used indoors, accounting for more than 80% of the total
market of public health insecticides. And, degradation rates of pyrethroids are
much lower in indoor than outdoor environments, that is because pyrethroids
have been detected at high levels in the indoor environments, with levels between
the range of low ng/m
3 and low μg/m
3 . Outdoor pyrethroid concentrations
were much lower, with values between pg/m
3 and low ng/m
3 range. In indoor
environments we must not forget either the contamination of house dust.
Pyrethroids are semi-volatile compounds with low vapor pressures and high
octanol/water and water/organic carbon partitioning coefficients facilitating their
absorption onto the organic component of house dust.
Some studies carried out in different areas of the world showed the presence of
pyrethroid insecticides in food products. The positive detection ranged between
10 and 30% of the samples analyzed and with the detection of between 2 and
5 different pyrethroids. In addition, in several cases the levels found exceed
the established maximum residue limits (MRLs). Thus, exposure to pyrethroids
through food consumption is reaching alarming levels. In any case, ingestion of
food and household dust are generally larger exposure routes than inhalation,
which contributes between 5 and 10% to the total exposure [9].
Numerous epidemiology studies have evaluated the association between health
outcomes in humans and pyrethroid exposure. Absorbed pyrethroids are quickly
metabolized and excreted, being the plasma half-life of pyrethroids in general less
than 8 h [10]. Many studies used urinary levels of metabolites to quantitatively
estimate pyrethroid exposure. However, pyrethroids are rapidly metabolized and
excreted, and a single measure of their urinary metabolites may only reflect current
or recent exposures, with misclassification of past exposures. In order to provide
more robust data on potential health outcomes from exposure to pyrethroids,
future epidemiological studies should quantify exposure over time.
Given the suspected effects of pesticides on the development of the fetus,
exposure to pyrethroids during pregnancy is a major public health concern.
Some studies suggest that environmental exposure to pyrethroids have adverse
effects on pregnancy outcomes and infant health, including birth size, immune
system, and neurodevelopment. One of the largest case-control studies suggested
that exposure to two or more pyrethroids during the first or second trimester of
pregnancy may increase the risk of spontaneous preterm birth [11]. Moreover,
in case-control studies in China, the geometric mean concentrations of urinary
pyrethroid metabolites of patients were higher than those of healthy children,
indicating that exposure to pyrethroids may be associated with an increased risk
of childhood brain tumors, childhood acute lymphocytic leukemia, and coronary
heart disease [12–14].
Human contact to one or more pyrethroid insecticides is likely. That because
future research works on risk assessment related with the exposure to pesticides
should focus on the analysis of total cumulative intake.
Acknowledgments This research study was funded by the Spanish Ministry of Transición
Ecológica y Reto Demográfico through the project APAN (Ref. 2392/2017) and by the Generalitat
de Catalunya (Consolidated Research Group: Water and Soil Quality unit 2017 SGR 1404).
312
E. Eljarrat
market of public health insecticides. And, degradation rates of pyrethroids are
much lower in indoor than outdoor environments, that is because pyrethroids
have been detected at high levels in the indoor environments, with levels between
the range of low ng/m
3 and low μg/m
3 . Outdoor pyrethroid concentrations
were much lower, with values between pg/m
3 and low ng/m
3 range. In indoor
environments we must not forget either the contamination of house dust.
Pyrethroids are semi-volatile compounds with low vapor pressures and high
octanol/water and water/organic carbon partitioning coefficients facilitating their
absorption onto the organic component of house dust.
Some studies carried out in different areas of the world showed the presence of
pyrethroid insecticides in food products. The positive detection ranged between
10 and 30% of the samples analyzed and with the detection of between 2 and
5 different pyrethroids. In addition, in several cases the levels found exceed
the established maximum residue limits (MRLs). Thus, exposure to pyrethroids
through food consumption is reaching alarming levels. In any case, ingestion of
food and household dust are generally larger exposure routes than inhalation,
which contributes between 5 and 10% to the total exposure [9].
Numerous epidemiology studies have evaluated the association between health
outcomes in humans and pyrethroid exposure. Absorbed pyrethroids are quickly
metabolized and excreted, being the plasma half-life of pyrethroids in general less
than 8 h [10]. Many studies used urinary levels of metabolites to quantitatively
estimate pyrethroid exposure. However, pyrethroids are rapidly metabolized and
excreted, and a single measure of their urinary metabolites may only reflect current
or recent exposures, with misclassification of past exposures. In order to provide
more robust data on potential health outcomes from exposure to pyrethroids,
future epidemiological studies should quantify exposure over time.
Given the suspected effects of pesticides on the development of the fetus,
exposure to pyrethroids during pregnancy is a major public health concern.
Some studies suggest that environmental exposure to pyrethroids have adverse
effects on pregnancy outcomes and infant health, including birth size, immune
system, and neurodevelopment. One of the largest case-control studies suggested
that exposure to two or more pyrethroids during the first or second trimester of
pregnancy may increase the risk of spontaneous preterm birth [11]. Moreover,
in case-control studies in China, the geometric mean concentrations of urinary
pyrethroid metabolites of patients were higher than those of healthy children,
indicating that exposure to pyrethroids may be associated with an increased risk
of childhood brain tumors, childhood acute lymphocytic leukemia, and coronary
heart disease [12–14].
Human contact to one or more pyrethroid insecticides is likely. That because
future research works on risk assessment related with the exposure to pesticides
should focus on the analysis of total cumulative intake.
Acknowledgments This research study was funded by the Spanish Ministry of Transición
Ecológica y Reto Demográfico through the project APAN (Ref. 2392/2017) and by the Generalitat
de Catalunya (Consolidated Research Group: Water and Soil Quality unit 2017 SGR 1404).
312
E. Eljarrat