Pyrethroids were the alternative to organochlorines and organophosphates
because of their low toxicity and persistence, usually lower than 90 days [2].
However, they are found in environmental samples, such as sediments and water
[3, 4], food [5, 6], mammals [7, 8] and humans [9, 10].
Agronomics should be an important source for the introduction of pyrethroids in
the environment. Conversely, it has been reported that the occurrence of pyrethroids
in rivers caused by agronomics fluctuates depending on their application [3].
Moreover, their use in agronomics has been banned in some countries with
legislation such as the Council Directive 91/414/EEC. On the other hand, they are
commonly used in industrial and domestic sectors. The United States Environmental
Protection Agency (EPA) Pesticides Industry Sales and Usage 2008–2012 Market
Estimates estimated that in 2012 between 450 and 1,360 t of pyrethroid active
ingredient were used only in the US home and garden market sector. Hence,
domestic and urban applications may be an important source [11].
Benthic organisms can be exposed to pyrethroids via ingestion or contact
with contaminated sediment particles or from interstitial water [7]. Fish can absorb
pyrethroids either through their gills due to their lipophilicity or through food webs.
All things considered, pyrethroids are still generally regarded as safe as fish
can oxidate them and mammals can hydrolyse them into non-toxic metabolites
[12, 13]. Most studies on exposure have been based on the analysis of these
metabolites in urine samples. This chapter reports data of the actual pyrethroids
accumulated in biota samples, including humans.
2 Bioavailability
Pyrethroids are applied for pest control in agricultural and urban areas. They are
easily adsorbed to sediment due to their very low water solubility (of a few μg/L)
and high hydrophobicity (with logarithms of their octanol-water partition coefficient
(K ow ) ranging from 5.7 to 7.6) [14].
Bioavailability plays a key role in sediment toxicity [15, 16]. Desorption of
chemicals from sediment occurs in different kinetic stages [17, 18]. There is a simple
method to assess the availability of contaminants associated with sediment
and, therefore, the fraction of them that is bioavailable [19]. This method uses
Tenax, a polymeric sorbent, in solid-phase extraction to measure the rate of mass
transfer from the sediment to the Tenax. Tenax has been applied to determine
desorption of contaminants like dichlorodiphenyltrichloroethane (DDT), polycyclic
aromatic hydrocarbons (PAHs), polybrominated diphenyl ethers (PBDEs) and
polychlorinated biphenyls (PCBs) [20, 21].
Many publications report that bioaccumulation levels are not a good estimate
of bioavailability for organic compounds that can be metabolized [22]. Additionally,
toxic compounds would kill sensitive species after exposure [23, 24]; thus
toxicity endpoints have been used with sensitive species to assess the bioavailable
pyrethroids in sediment samples [25].
Bioavailability and Bioaccumulation of Pyrethroid Insecticides in Wildlife and. . .
207
because of their low toxicity and persistence, usually lower than 90 days [2].
However, they are found in environmental samples, such as sediments and water
[3, 4], food [5, 6], mammals [7, 8] and humans [9, 10].
Agronomics should be an important source for the introduction of pyrethroids in
the environment. Conversely, it has been reported that the occurrence of pyrethroids
in rivers caused by agronomics fluctuates depending on their application [3].
Moreover, their use in agronomics has been banned in some countries with
legislation such as the Council Directive 91/414/EEC. On the other hand, they are
commonly used in industrial and domestic sectors. The United States Environmental
Protection Agency (EPA) Pesticides Industry Sales and Usage 2008–2012 Market
Estimates estimated that in 2012 between 450 and 1,360 t of pyrethroid active
ingredient were used only in the US home and garden market sector. Hence,
domestic and urban applications may be an important source [11].
Benthic organisms can be exposed to pyrethroids via ingestion or contact
with contaminated sediment particles or from interstitial water [7]. Fish can absorb
pyrethroids either through their gills due to their lipophilicity or through food webs.
All things considered, pyrethroids are still generally regarded as safe as fish
can oxidate them and mammals can hydrolyse them into non-toxic metabolites
[12, 13]. Most studies on exposure have been based on the analysis of these
metabolites in urine samples. This chapter reports data of the actual pyrethroids
accumulated in biota samples, including humans.
2 Bioavailability
Pyrethroids are applied for pest control in agricultural and urban areas. They are
easily adsorbed to sediment due to their very low water solubility (of a few μg/L)
and high hydrophobicity (with logarithms of their octanol-water partition coefficient
(K ow ) ranging from 5.7 to 7.6) [14].
Bioavailability plays a key role in sediment toxicity [15, 16]. Desorption of
chemicals from sediment occurs in different kinetic stages [17, 18]. There is a simple
method to assess the availability of contaminants associated with sediment
and, therefore, the fraction of them that is bioavailable [19]. This method uses
Tenax, a polymeric sorbent, in solid-phase extraction to measure the rate of mass
transfer from the sediment to the Tenax. Tenax has been applied to determine
desorption of contaminants like dichlorodiphenyltrichloroethane (DDT), polycyclic
aromatic hydrocarbons (PAHs), polybrominated diphenyl ethers (PBDEs) and
polychlorinated biphenyls (PCBs) [20, 21].
Many publications report that bioaccumulation levels are not a good estimate
of bioavailability for organic compounds that can be metabolized [22]. Additionally,
toxic compounds would kill sensitive species after exposure [23, 24]; thus
toxicity endpoints have been used with sensitive species to assess the bioavailable
pyrethroids in sediment samples [25].
Bioavailability and Bioaccumulation of Pyrethroid Insecticides in Wildlife and. . .
207