80
H. Toyofuku
level identified in the draft Codex Standard (20 mg/kg), and the WG agreed that the
level of 20 mg/kg is appropriate (Codex 2006b). No further discussion was noted in
the report of the 28th CCFFP (Codex 2006a).
With regards to the okadaic acid (OA) group of toxins, OA and dinophysistoxins
(DTXs) possess tumour-promoting activity; OA also possesses genotoxic and
immunotoxic activity. These effects raise questions as to the human health risks of
(sub)-chronic exposure to low levels of these compounds. A pressing problem was
the lack of sufficient quantities of purified toxins to perform sub-chronic animal
toxicity studies. The pWG determined that no TDI could be established because of
insufficient data on the chronic effects of OA, and established a provisional ARfD
of 0.33 g OA equ/kg bw, based on the LOAEL of 1.0 g OA/kg bw. A safety
factor of 3 was chosen because of documented human cases involving more than
40 people and because DSP symptoms are readily reversible. The consumption of
100, 250 or 380 g shellfish meat by adults would lead to a derived guidance level
of 0.2, 0.08 or 0.05 mg OA equivalent/kg shellfish meat, respectively (Toyofuku
2006). The pWG discussed the action levels used in various countries and the level
of consumer protection which they have provided to date. The current standard, its
practical application and demonstrated results indicate that the level of 0.16 mg/kg
provides adequate protection for consumers (Codex 2006b).
With regards to the saxitoxin group (STX) of toxins, the pWG established a
provisional ARfD of 0.7 g STX equivalents/kg bw, based on an LOAEL of 2 g
STX equ/kg bw. A safety factor of 3 was chosen because documented human cases
included a wide spectrum of people (occupation, age, and sex) and mild illness is
readily reversible. The Expert Consultation determined no TDI could be established
because of insufficient data on the chronic effects of STX. As shown in Table 7.1,
the consumption of 100, 250 or 380 g shellfish meat by adults would lead to a
derived guidance level of 0.42, 0.17 or 0.11 mg STX equ/kg, respectively (Toyofuku
2006). The pWG considered that the long-standing enforced tolerance limit of
0.8 mg/kg STX.2HCl equiv., established for consumer protection, was considered
to be successful (over nearly 50 years), with no human illnesses from commercially
harvested product (Codex 2006b).
The CCFFP during the 28th session agreed to advance the Proposed Draft
Standard for Live and Raw Bivalve Molluscs to Step 5 for adoption by the 30th
Session of the Commission. The sections on hygiene (including biotoxin level)
would be sent to the CCFH for endorsement. At the 38th session of the CCFH,
the CCFH was of the opinion that these provisions on marine biotoxins should
be considered under the section on contaminants in the draft Standard and that
consideration of these issues were outside the competence of the CCFH. The
CCFH was of the view that the matter of marine biotoxins should be sent to
the Codex Committee on Contaminants in Food (CCCF) for their advice and
endorsement, if necessary (Codex 2007a). At the 2nd session of the CCCF in 2008,
the representative of WHO noted that the levels proposed by the CCFFP were
different to those proposed by the expert consultation and expressed concern that
the current proposed levels might exceed those of the ARfD for several marine
biotoxins at normal consumption levels. The WHO representative also expressed
H. Toyofuku
level identified in the draft Codex Standard (20 mg/kg), and the WG agreed that the
level of 20 mg/kg is appropriate (Codex 2006b). No further discussion was noted in
the report of the 28th CCFFP (Codex 2006a).
With regards to the okadaic acid (OA) group of toxins, OA and dinophysistoxins
(DTXs) possess tumour-promoting activity; OA also possesses genotoxic and
immunotoxic activity. These effects raise questions as to the human health risks of
(sub)-chronic exposure to low levels of these compounds. A pressing problem was
the lack of sufficient quantities of purified toxins to perform sub-chronic animal
toxicity studies. The pWG determined that no TDI could be established because of
insufficient data on the chronic effects of OA, and established a provisional ARfD
of 0.33 g OA equ/kg bw, based on the LOAEL of 1.0 g OA/kg bw. A safety
factor of 3 was chosen because of documented human cases involving more than
40 people and because DSP symptoms are readily reversible. The consumption of
100, 250 or 380 g shellfish meat by adults would lead to a derived guidance level
of 0.2, 0.08 or 0.05 mg OA equivalent/kg shellfish meat, respectively (Toyofuku
2006). The pWG discussed the action levels used in various countries and the level
of consumer protection which they have provided to date. The current standard, its
practical application and demonstrated results indicate that the level of 0.16 mg/kg
provides adequate protection for consumers (Codex 2006b).
With regards to the saxitoxin group (STX) of toxins, the pWG established a
provisional ARfD of 0.7 g STX equivalents/kg bw, based on an LOAEL of 2 g
STX equ/kg bw. A safety factor of 3 was chosen because documented human cases
included a wide spectrum of people (occupation, age, and sex) and mild illness is
readily reversible. The Expert Consultation determined no TDI could be established
because of insufficient data on the chronic effects of STX. As shown in Table 7.1,
the consumption of 100, 250 or 380 g shellfish meat by adults would lead to a
derived guidance level of 0.42, 0.17 or 0.11 mg STX equ/kg, respectively (Toyofuku
2006). The pWG considered that the long-standing enforced tolerance limit of
0.8 mg/kg STX.2HCl equiv., established for consumer protection, was considered
to be successful (over nearly 50 years), with no human illnesses from commercially
harvested product (Codex 2006b).
The CCFFP during the 28th session agreed to advance the Proposed Draft
Standard for Live and Raw Bivalve Molluscs to Step 5 for adoption by the 30th
Session of the Commission. The sections on hygiene (including biotoxin level)
would be sent to the CCFH for endorsement. At the 38th session of the CCFH,
the CCFH was of the opinion that these provisions on marine biotoxins should
be considered under the section on contaminants in the draft Standard and that
consideration of these issues were outside the competence of the CCFH. The
CCFH was of the view that the matter of marine biotoxins should be sent to
the Codex Committee on Contaminants in Food (CCCF) for their advice and
endorsement, if necessary (Codex 2007a). At the 2nd session of the CCCF in 2008,
the representative of WHO noted that the levels proposed by the CCFFP were
different to those proposed by the expert consultation and expressed concern that
the current proposed levels might exceed those of the ARfD for several marine
biotoxins at normal consumption levels. The WHO representative also expressed