254
10 Illustrative Case Study
• Mass in the different compartments: m s , m w , m a (in mol or kg)
• First-order degradation rate constants in the compartments: k s , k w , k a (in
s −1 )
• Emissions into the compartments: E s , E w , E a (in mol/hr or kg/hr)
• First-order transfer rate constants between the compartments: t as , t sa , t aw ,
t wa , t ws , t sw (in s −1 )
(b) In order to run the level III model, the emission rate of ASM is needed in
addition to the earlier parameters used for the level I model and provided
in Table 10.6. Use the assumed ASM concentration, application rate, and
application interval in Table 10.7 to calculate the estimated continuous emission
rate [mol/hr] of ASM into 1 hectare of soil during the growing season.
(c) In the small-region model (Scheringer and MacLeod, 2021), update the partition
coefficients, degradation half-lives, and fractions covered by water and soil
to match those used previously in the small-world model. Update the total
surface area parameter to represent 1 hectare of land. Keep all of the other
parameters as their default values. Now, obtain the expected distributions in
the different environmental compartments using the level III solution. Perform
this analysis for the following four emission scenarios using the calculated
continuous emission rate:
• Emission only to air (e.g., represents spraying the product from above onto
the agricultural field)
• Emission only to water (e.g., represents when the product is accidentally
spilled into surface water)
• Emission only to soil
• Emission only to sediments
(d) Comment on the resulting predicted distribution for each of the four emission
scenarios. What is the relationship between the emission scenario and the
distribution of the chemical in the environment?
(e) What are the assumptions and limitations of the level III model? What is
required to obtain a more realistic environmental fate model?
10.4.2.2 Human Exposure: Occupational
Occupational exposure to crop protection products can be assessed using various
methods such as modeling (as a lower tier) and field studies measuring real-life
operator exposure (as a higher tier). Here, occupational exposure will be investigated
using a simple exposure assessment model developed by the European Food Safety
Authority (EFSA). This spreadsheet-based tool has been published as a part of
EFSA’s guidance document on the assessment of exposure to pesticides (EFSA,
2014b). Background information describing the guidance criteria implemented in
the tool is provided in the EFSA publication itself, and the tool can be downloaded
as a spreadsheet-based file from the publication’s supporting information.
10 Illustrative Case Study
• Mass in the different compartments: m s , m w , m a (in mol or kg)
• First-order degradation rate constants in the compartments: k s , k w , k a (in
s −1 )
• Emissions into the compartments: E s , E w , E a (in mol/hr or kg/hr)
• First-order transfer rate constants between the compartments: t as , t sa , t aw ,
t wa , t ws , t sw (in s −1 )
(b) In order to run the level III model, the emission rate of ASM is needed in
addition to the earlier parameters used for the level I model and provided
in Table 10.6. Use the assumed ASM concentration, application rate, and
application interval in Table 10.7 to calculate the estimated continuous emission
rate [mol/hr] of ASM into 1 hectare of soil during the growing season.
(c) In the small-region model (Scheringer and MacLeod, 2021), update the partition
coefficients, degradation half-lives, and fractions covered by water and soil
to match those used previously in the small-world model. Update the total
surface area parameter to represent 1 hectare of land. Keep all of the other
parameters as their default values. Now, obtain the expected distributions in
the different environmental compartments using the level III solution. Perform
this analysis for the following four emission scenarios using the calculated
continuous emission rate:
• Emission only to air (e.g., represents spraying the product from above onto
the agricultural field)
• Emission only to water (e.g., represents when the product is accidentally
spilled into surface water)
• Emission only to soil
• Emission only to sediments
(d) Comment on the resulting predicted distribution for each of the four emission
scenarios. What is the relationship between the emission scenario and the
distribution of the chemical in the environment?
(e) What are the assumptions and limitations of the level III model? What is
required to obtain a more realistic environmental fate model?
10.4.2.2 Human Exposure: Occupational
Occupational exposure to crop protection products can be assessed using various
methods such as modeling (as a lower tier) and field studies measuring real-life
operator exposure (as a higher tier). Here, occupational exposure will be investigated
using a simple exposure assessment model developed by the European Food Safety
Authority (EFSA). This spreadsheet-based tool has been published as a part of
EFSA’s guidance document on the assessment of exposure to pesticides (EFSA,
2014b). Background information describing the guidance criteria implemented in
the tool is provided in the EFSA publication itself, and the tool can be downloaded
as a spreadsheet-based file from the publication’s supporting information.