Environmental Engineering Reference
In-Depth Information
contaminant transfer rate or elimination rate to milk or eggs [d -1 ]
k a =
λ a =
rate of contaminant degradation plus elimination by pathways other than
excretion of milk or eggs [d 1 ]
If I a is constant with time , the mass of contaminant in animal is as follows:
1
e ( k a + λ a ) × t
f abs , a ×
I a
k a + λ a
e ( k a + λ a ) × t
m a ,1 ( t )
=
×
+
m a ,1 (0)
×
(11.9)
and
1
e ( k a + λ a ) × t
f abs , a ×
I a
m a ,1 (0)
M a ,1 ( t ) ×
e ( k a + λ a ) × t
C a ,1 ( t )
=
M a ,1 ( t ) ×
+
(11.10)
( k a + λ a )
×
in which
=
C a, 1 ( t )
contaminant concentration in animal tissues at time t [mg/kg]
M a ,1 ( t )
=
weight of the animal tissues at time t [kg]
If m a ,1 (0)
=
0 then,
1
e ( k a + λ a ) × t
f abs , a ×
I a
C a ,1 ( t )
=
M a ,1 ( t ) ×
(11.11)
( k a + λ a )
×
When the contaminant is mainly accumulated in fat tissue, the fat concentration
can be calculated from the previous equations ( C a ,1 ( t )
=
contaminant concentration
in fat tissues and M a, 1 ( t )
weight of fat tissue in the animal at time t ) and the meat
concentration can be derived from C a ,1 by multiplying it by the fraction of fat in
meat.
If I a varies with time , m a ,1 has to be integrated on time intervals
=
T where I a
may be regarded as constant:
1
e ( k a + λ a ) × T
f abs , a ×
I a
( k a + λ a ) ×
e ( k a + λ a ) × T
m a ,1 ( t )
=
+
×
m a ,1 ( t
T )
(11.12)
and
m a ,1 ( t )
M a ,1 ( t )
C a ,1 ( t )
=
(11.13)
When for very lipophilic contaminants there is neither metabolism, nor elimi-
nation via milk or eggs (e.g., in case of beefs or chickens), concentrations can be
assessed as follows, as elimination via urine is assumed to be low:
t i = 0
T
×
( t i
×
[ I a ( t i )
t i 1 )]
f abs , a
C a ,1 ( T )
=
(11.14)
M a ,1 ( T )
 
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