10 Probabilistic Exposure Assessment to Phycotoxins by Recreational. . .
123
Since the margin of exposure is higher than 100, it appears that acute SPX is not
a matter of concern for human health. But this conclusion has to be confirmed with
other relevant toxicological studies, after establishing an ARfD for SPX.
Chronic Risk Characterization
For chronic risk characterization, probabilistic estimates of dietary exposure to
phycotoxins have to be compared to the TDI. But, as no TDI has been allocated
to phycotoxins by international committees, we used two other methods, not
satisfactory but the only ones possible: comparison with the corresponding ARfD
and with Threshold of Toxicological Concern (TTC). The TTC is a principle, which
refers to the establishment of a human exposure threshold value for all chemicals,
below which there would be no appreciable risk to human health. This threshold
value is equal to 2.5 ng/kg bw/day for genotoxic substances and 25 ng/kg bw/day
for all other substances (Kroes et al. 2002; EFSA 2010).
Domoic Acid and Analogs
Comparison with TTC: concerning DAs, the levels of exposure are equal to 110; 90
and 260 ng/kg bw/day, for the mean, median and 95th percentile, respectively.
These levels of exposure are not below the TTC, thus it cannot be excluded that
there would be a risk to human health.
Comparison with ARfD: according to the probabilistic approach, the mean and
95th percentile intakes for DA (0.11 and 0.26 g/kg bw/day, respectively) are
about 100- and 250-fold less than the most conservative ARfD. Despite the lack
of TDI allocated to DA by international committees, Mari¨ en (1996) estimated
that a value of 75 g/kg bw provides a sound basis for a TDI. The daily DA
intakes found in this study are, at least, about 300-fold less than the proposal by
Mari¨ en (1996).
Okadaic Acid and Analogs
Comparison with TTC: concerning OAs, the levels of exposure are equal to 54; 39
and 149 ng/kg bw/day, for the mean, median and 95th percentile, respectively.
These levels of exposure are not below the TTC, thus it cannot be excluded that
there would be a risk to human health.
Comparison with ARfD: for OAs, the values of the mean and 95th percentile
intake issued from the probabilistic approach (0.054 and 0.15 g/kg bw/day,
respectively) are only about five- and two-fold less than the most protective
OA ARfD (0.30 g/kg bw). Thus chronic OA intakes were close to ARfD.
TDI is, by definition, less than ARfD. The former is, derived from a NOAEL
123
Since the margin of exposure is higher than 100, it appears that acute SPX is not
a matter of concern for human health. But this conclusion has to be confirmed with
other relevant toxicological studies, after establishing an ARfD for SPX.
Chronic Risk Characterization
For chronic risk characterization, probabilistic estimates of dietary exposure to
phycotoxins have to be compared to the TDI. But, as no TDI has been allocated
to phycotoxins by international committees, we used two other methods, not
satisfactory but the only ones possible: comparison with the corresponding ARfD
and with Threshold of Toxicological Concern (TTC). The TTC is a principle, which
refers to the establishment of a human exposure threshold value for all chemicals,
below which there would be no appreciable risk to human health. This threshold
value is equal to 2.5 ng/kg bw/day for genotoxic substances and 25 ng/kg bw/day
for all other substances (Kroes et al. 2002; EFSA 2010).
Domoic Acid and Analogs
Comparison with TTC: concerning DAs, the levels of exposure are equal to 110; 90
and 260 ng/kg bw/day, for the mean, median and 95th percentile, respectively.
These levels of exposure are not below the TTC, thus it cannot be excluded that
there would be a risk to human health.
Comparison with ARfD: according to the probabilistic approach, the mean and
95th percentile intakes for DA (0.11 and 0.26 g/kg bw/day, respectively) are
about 100- and 250-fold less than the most conservative ARfD. Despite the lack
of TDI allocated to DA by international committees, Mari¨ en (1996) estimated
that a value of 75 g/kg bw provides a sound basis for a TDI. The daily DA
intakes found in this study are, at least, about 300-fold less than the proposal by
Mari¨ en (1996).
Okadaic Acid and Analogs
Comparison with TTC: concerning OAs, the levels of exposure are equal to 54; 39
and 149 ng/kg bw/day, for the mean, median and 95th percentile, respectively.
These levels of exposure are not below the TTC, thus it cannot be excluded that
there would be a risk to human health.
Comparison with ARfD: for OAs, the values of the mean and 95th percentile
intake issued from the probabilistic approach (0.054 and 0.15 g/kg bw/day,
respectively) are only about five- and two-fold less than the most protective
OA ARfD (0.30 g/kg bw). Thus chronic OA intakes were close to ARfD.
TDI is, by definition, less than ARfD. The former is, derived from a NOAEL