passively collects SVOCs including pyrethroids [26]. The silicone wristband is
extracted and analyzed by gas chromatography/mass spectrometry or by gas chromatography/electron capture detection for the pyrethroids. The latter, while not
positively confirming the compound’s identity, often has a lower detection limit.
The silicone wristband has the benefit of requiring little field effort and wearing it
presents relatively low participant burden that is often acceptable to individuals
across both genders and over a wide range of ages and ethnic groups. However, the
amount collected on the wristband may have contributions from dermal contact and
is dependent upon the compound’s diffusion rate which varies based on if the
wristband is opened to the air or covered by clothing and the time period it is
worn. Therefore, the amount collected does not readily translate to average personal
air concentrations [27] but rather provides a relative measure of the air concentration
encountered and provides confirmation that inhalation exposure occurred. Table 1
lists a number of studies conducted in different countries using this method and the
pyrethroids detected along with the mass collected on the silicone wristband. In
addition to detecting several pyrethroids in multiple settings, piperonyl butoxide, a
synergist added to pyrethroid application mixtures, was found in wristbands for
more than half of the participants.
6 Indoor Air Levels
While the quantity of pesticides sprayed outdoors during a single application in
agricultural settings is typically much higher than the amount sprayed indoors, indoor
pyrethroid air concentrations and the associated exposures can be higher than outdoors. Spraying indoors may occur in close proximity to individuals not wearing
personal protective equipment (PPE) such as a respirator or gloves. Further, spraying
indoors is done within a confined space, while spraying outdoors has significantly
more dilution due to the open area and wind. A variety of factors that degrade
pyrethroid residue outdoors, e.g., sunshine, precipitation, and temperature extremes,
are either not present or less extreme indoors extending their residence time in indoor
settings compared to outdoors [32]. Elevated pyrethroid air concentrations can also
occur indoors from the redistribution of these compounds from sprayed surfaces
when the pyrethroids volatilize, redistribute onto dust, and become resuspended
[33]. Pyrethroid pesticides are SVOCs with low vapor pressures and high octanol/
water and water/organic carbon partitioning coefficients facilitating their absorption
onto the organic component of house dust. House dust has been shown to be a
reservoir for many SVOCs, including pesticides [34]. An additional concern for
pyrethroids present in indoor air is that they are breathed by a range of individuals,
including those potentially more sensitive to adverse health effects than the healthy
workers including children, the elderly, and individuals with preexisting health
conditions. Further, the amount of time that people spend indoors (>90%) exceeds
that spent outdoors, which for the general population is <10% and for workers
20–50% (35–40 h/week). This results in more exposure to indoor contaminants.
232
C. P. Weisel
extracted and analyzed by gas chromatography/mass spectrometry or by gas chromatography/electron capture detection for the pyrethroids. The latter, while not
positively confirming the compound’s identity, often has a lower detection limit.
The silicone wristband has the benefit of requiring little field effort and wearing it
presents relatively low participant burden that is often acceptable to individuals
across both genders and over a wide range of ages and ethnic groups. However, the
amount collected on the wristband may have contributions from dermal contact and
is dependent upon the compound’s diffusion rate which varies based on if the
wristband is opened to the air or covered by clothing and the time period it is
worn. Therefore, the amount collected does not readily translate to average personal
air concentrations [27] but rather provides a relative measure of the air concentration
encountered and provides confirmation that inhalation exposure occurred. Table 1
lists a number of studies conducted in different countries using this method and the
pyrethroids detected along with the mass collected on the silicone wristband. In
addition to detecting several pyrethroids in multiple settings, piperonyl butoxide, a
synergist added to pyrethroid application mixtures, was found in wristbands for
more than half of the participants.
6 Indoor Air Levels
While the quantity of pesticides sprayed outdoors during a single application in
agricultural settings is typically much higher than the amount sprayed indoors, indoor
pyrethroid air concentrations and the associated exposures can be higher than outdoors. Spraying indoors may occur in close proximity to individuals not wearing
personal protective equipment (PPE) such as a respirator or gloves. Further, spraying
indoors is done within a confined space, while spraying outdoors has significantly
more dilution due to the open area and wind. A variety of factors that degrade
pyrethroid residue outdoors, e.g., sunshine, precipitation, and temperature extremes,
are either not present or less extreme indoors extending their residence time in indoor
settings compared to outdoors [32]. Elevated pyrethroid air concentrations can also
occur indoors from the redistribution of these compounds from sprayed surfaces
when the pyrethroids volatilize, redistribute onto dust, and become resuspended
[33]. Pyrethroid pesticides are SVOCs with low vapor pressures and high octanol/
water and water/organic carbon partitioning coefficients facilitating their absorption
onto the organic component of house dust. House dust has been shown to be a
reservoir for many SVOCs, including pesticides [34]. An additional concern for
pyrethroids present in indoor air is that they are breathed by a range of individuals,
including those potentially more sensitive to adverse health effects than the healthy
workers including children, the elderly, and individuals with preexisting health
conditions. Further, the amount of time that people spend indoors (>90%) exceeds
that spent outdoors, which for the general population is <10% and for workers
20–50% (35–40 h/week). This results in more exposure to indoor contaminants.
232
C. P. Weisel