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Chemistry International
Vol. 24, No. 5
September 2002
Pesticide
Residues
IUPAC
Representatives Report on the 34th Codex Committee Session
The Codex Committee
on Pesticide Residues (CCPR) convened at The Hague this past May to
continue its mission of promulgating recommendations on international
standards for maximum residue level (MRL) of pesticides on internationally
traded agricultural commodities. In this report, Kenneth Racke,
the IUPAC representative on Codex, offers a brief summary and major
highlights of the past meeting. The CCPR serves as a forum for discussion
and decisions regarding aspects of MRL process risk management. Actual
technical recommendations regarding MRLs and the acceptable daily intake
(ADI) and acute reference dose (ARfD) toxicological endpoints arise
from the annual Joint Meeting on Pesticide Residues (JMPR) of the Food
and Agricultural Organization of the United Nations/World Health Organization
(FAO/WHO). MRLs recommended by CCPR are subject to formal approval by
the biennial Codex Alimentarius Commission (CAC) as Codex MRLs.
<www.iupac.org/standing/on/ccpr>
Big
Group, Small Steps
Referrals from CAC and JMPR
Protection of Infants and Children
Acute Dietary Intake Assessment
Cumulative Dietary Intake Assessment
Criteria for Prioritization
Tentative JMPR Schedule
Accelerating the Codex MRL Process
MRLs for Minor Crops
OPs and Carbamates
EMRLs
by
Kenneth D. Racke
Big
Group, Small Steps
Two-hundred-fifty
delegates representing 51 countries and 15 international organizations
attended but, as is typical, achieved few definitive outcomes or concrete
decisions. The CCPR enthusiastically debates particular topics and position
papers, appoints working groups to prepare new or revised position papers
for future discussion, and refers technical matters to the JMPR for
learned consideration. Eventually, the CCPR recommends finalized policies
and MRLs that have proceeded through an eight-step process to formal
adoption by the CAC.
In addition
to the frequent interventions of national delegations, opinions aplenty
were forthcoming from the manufacturers representative, CropLife
International, and the self-appointed committee conscience, Consumers
International. With CropLife International anxious to see reasonable
and pragmatic progress in promulgation of MRLs and Consumers International
most concerned that the precautionary principle be observed with every
action, these delegations found little common ground.
Referrals
from CAC and JMPR
Acting
on an early agenda item, the committee initiated a comprehensive review
of the standard-setting and technical-evaluation processes employed
by all Codex-sponsored bodies, including that of CCPR and JMPR. An independent
panel of experts report will be available for discussion at the
July 2003 CAC meeting and could yield recommendations for process changes
or further study. Included in the ongoing review will be an overall
consideration of harmonized approaches across all Codex bodies toward
food standards establishment and the associated risk analysis and management.
Several
general considerations from the 2001 JMPR were briefly discussed. Among
them, the WHO will be developing a guidance document on ARfD establishment.
A pilot program for sharing chemical reviews from national regulatory
authorities with the JMPR will be advanced later. The JMPR also noted
impending availability of a new guidance document, "FAO Plant Production
and Protection Paper 170," on the submission and evaluation of
pesticide residue data for MRL estimation.
Protection
of Infants and Children
The Consumers
International delegation requested that CCPR give further consideration
to special MRLs for processed commodities such as infant formula and
cereals. Back in 2000, the CCPR debated the need for default MRLs for
those commodities and concluded that no such initiative was warranted
since children were already well protected by the current MRL-setting
process. The CCPR had recommended that food preparation methods be generally
practiced that best minimize pesticide residue carryover. The CCPR recommendation
to the Codex Committee on Nutrition and Foods for Special Dietary Uses
for adoption of such language had been debated and supported. So, the
committee decided that reconsideration was fruitless and inimical to
progress in MRL setting.
Acute
Dietary Intake Assessment
For the
past couple of years, JMPR has undertaken to establish ARfDs and conduct
acute dietary intake (ADI) assessments on a commodity-by-commodity basis
using a simple, deterministic calculation. Short-term intake calculations
are resulting in a significant number of cautions being raised which
are blocking advancements of MRLs for approximately half of the pesticides
examined. This stands in opposition to long-term dietary intake assessment,
which infrequently is observed to exceed the ADI. The WHOs Dr.
Jerry Moy shared example calculations for the organophosphorus (OP)
insecticide disulfoton and highlighted his reliance for large-portion
size estimates on the data matrix he has constructed to reflect the
highest intake for each commodity at the 97.5 percentile reported from
any single country. He reported that the delegation from South Africa
had just supplied data which would increase the highest maize grain
intake by some 25-fold. Based on that new data, the committee agreed
with Dr. Moys suggestion that all past short-term intake assessments
for maize be recalculated.
A discussion
of probabilistic ADI assessment followed, based on the paper prepared
by the USA in cooperation with The Netherlands, Australia, CropLife
International, and Consumers International. The paper highlighted the
probabilistic assessment methodology employed by the U.S. Environmental
Protection Agency andwhile emphasizing the refined nature of such
an approach in providing the most accurate reflection of the likelihood
of any particular exposure across all crop commoditiesalso reflected
its data-intensive nature. The majority of delegations were pessimistic
about the utility of such an approach in light of the scarcity of data
distributions at the international level on large-portion size consumption
and limited JMPR technical resources. Germany also indicated that significant
policy decisions would also be required, citing the selection of reference
level as a particularly thorny issue. Based on the interest but lack
of firm support, the committee referred the matter to JMPR for a technical
opinion and will await the outcome of the general evaluation of risk
assessment approaches planned as part of the ongoing CAC review process.
Regarding
refinement of the currently employed methodology for acute dietary intake
assessment, the committee noted a nearly completed IUPAC project (see
www.iupac.org/projects/1999/1999-009-1-600.html),
agreed to consider advancements in acute dietary assessment calculations,
and appointed the Netherlands to work with IUPAC and several other delegations
to bring specific discussions forward for the 2003 CCPR meeting.
Cumulative
Dietary Intake Assessment
At earlier
CCPR meetings, the committee expressed an intention to take into consideration
the cumulative intake of dietary pesticides that share a common toxicity
mechanism. The USA delegation presented a paper outlining the current
approach being pioneered by the U.S. EPA with the OP class of insecticides.
The USA delegation noted the preliminary nature of methods for such
an assessment, but projected finalization of a first example by mid-2002.
A few delegations noted the importance and desirability of including
such considerations at the international level, but there were considerable
reservations expressed for such an approach based on the complexity
and data-rich nature of such methodology. Several delegations also noted
the prerequisite of developing a probabilistic methodology before such
cumulative intake assessments could be considered. The committee agreed
that, given the immature nature of cumulative assessment approaches
at even the national level, it was too early for CCPR to undertake any
actions related to cumulative dietary intake assessment.
Criteria
for Prioritization
The criteria
employed by CCPR in prioritizing new chemical evaluations and periodic
reevaluations of existing chemicals were debated based on a paper presented
by the Australian delegation. The need for prioritization is driven
by JMPR overcapacity in handling a significant backlog of technical
evaluation requests. As a general principle, the committee agreed to
maintain a 50:50 ratio between new and existing chemical evaluations.
With the assumption that candidate products must give rise to residues
in food commodities moving in international trade and which may give
rise to public health concerns and/or impediments to trade, CCPR agreed
once again that when establishing priorities, preference be given to
those chemicals:
- the
intake and/or toxicity profile of which indicate a high level of public
concern
-
that are new and safer and have the potential to replace existing
chemicals that present a public health concern l on which national
reviews are available
-
that may be responsible for actual or potential losses owing to trade
disruption
The USA
delegation, Consumers International, and a few other delegations
supported making the "safer" or "reduced risk" pesticide
prioritization criterion broader in scope than just "public health"
to include descriptions such as "reduced environmental impact,"
"safer for applicators," and "replacement of ozone depleter."
The committee agreed that such factors could be taken into account in
prioritization, but that they were secondary to public health considerations
and likely already being taken into account when nominating "reduced
risk" pesticides for CCPR prioritization.
Tentative
JMPR Schedule
The Australian
delegation also presented the report of the Ad Hoc Working Group on
the Establishment of Codex Priority Lists of Pesticides. The committee
accepted the report with several modifications related to agenda items
that came up during the CCPR meeting. Of particular interest were the
new chemical toxicological (T) and residue chemistry (R) evaluations
scheduled for future JMPR meetings:
-
2002 JMPR: esfenvalerate (T,R), flutolanil (T,R), imidacloprid (R)
-
2003 JMPR: cyprodinil (T,R), famoxadone (T,R), methoxyfenozide (T,R),
pyraclostrobin (T,R)
-
2004 JMPR: fludioxinil (T,R), zeta-/alpha-cypermethrin (T,R), trifloxystrobin
(T,R)
-
2005 JMPR: dimethenamid-P (T,R), fenhexamid (T,R), indoxacarb (T,R),
novaluron (T,R)
Accelerating
the Codex MRL Process
A report
focused on the Codex MRL process refinement and acceleration provoked
considerable discussion. Unfortunately, the committee agreed on few
practical steps and a move toward acceleration appears likely to proceed
at an agonizingly slow pace. The bulk of the discussion centered around
a paper introduced by the USA delegation that focused on options for
solving the "window of vulnerability" in trade resulting from
the extensive time required to establish Codex MRLs. The process from
new compound nomination for MRLs to promulgation of those MRLs may take
four or more years. The paper highlighted eight practical suggestions,
which ranged from simple, no-cost administrative changes such as holding
the JMPR three months earlier so that first CCPR discussion can occur
the next year, to extensive and costly program overhauls such as replacing
the volunteer JMPR with a full-time technical evaluation staff. Projected
process savings ranged from one to six years.
One idea
that attracted much discussion was the establishment of "interim
Codex MRLs" based on early adoption of the JMPR evaluations or
reference to national evaluations and MRLs. Although a number of delegations
supported serious consideration of such options, others were concerned
about the need for caution and additional procedural safeguards. The
only points of consensus emerging included the preparation of yet another
paper for further discussion at the 2003 CCPR meeting and for CCPR to
review MRL proposals at Step 3 the year following the JMPR meeting instead
of automatically postponing by another year.
MRLs
for Minor Crops
A paper
prepared by the Spice Trade Association and introduced by the South
Africa delegation, which highlighted the problem of MRLs for dried spices,
also prompted discussion. Many of these products come from small farms
in developing countries lacking adequate description of good agricultural
practice in the use of pesticides and supervised field residue trials.
Given the generally limited dietary intake of such commodities, it was
proposed to base Codex MRLs and extraneous maximum residue limits (EMRLs)
on available monitoring data as long as several criteria were met, including
per capita consumption <0.5% of regional diets, substantial trade
involvement, and availability of ongoing residue monitoring data from
the producing country. The committee agreed to ask JMPR to establish
guidance on monitoring data submission and also to have South Africa
prepare a paper for discussion at the 2003 CCPR providing a definition
and listing of candidate spices. The committee noted that current considerations
be restricted to spices and not include tea, fresh herbs, or tropical
fruitsall minor crops with similar MRL problems to spices. Future
discussion on these leftover points is anticipated, and a recently initiated
IUPAC project dealing with international chemistry and regulatory aspects
for minor crops should also provide additional guidance (see www.iupac.org/projects/2001/2001-039-1-600.html).
OPs
and Carbamates
Some of
the more acutely toxic OP and carbamate insecticides were the subject
of CCPR discussions and actions. Due to implementation of the periodic
reevaluation process and acute dietary intake assessment, a number of
Codex MRLs for these insecticides are being put on hold or being revoked
based on inadequate numbers of residue trials, especially for minor
crops, and short-term intake concerns. Most or all MRLs are being revoked
for bendiocarb, fenitrothion, fenthion, mebarbam, mevinphos, monocrotophos,
parathion, and phosphamidon. A significant number of MRLs are being
stalled or revoked for aldicarb, carbofuran, diazinon, dimethoate, methamidaphos,
methomyl, parathionmethyl, phosalone, and phosmet.
EMRLs
In addition
to MRLs based on approved uses, CCPR has also established EMRLs for
compounds no longer used, but for which inadvertent contamination of
food commodities may occur. There are a number of EMRLs for DDT (21),
and the 1996 JMPR had recommended revised values for mammal meat and
poultry products based on available monitoring data and projected frequency
of noncompliance rates for commodity shipments. The CAC had considered
decreased EMRLs for meat during 2001 based on a CCPR proposal, but could
not reach consensus. The committee agreed to indefinitely shelve the
revised meat MRL proposal for DDT, but would in the future determine
availability of new monitoring data to support future discussions. However,
a proposed poultry meat MRL advanced to Step 5 for future consideration.
The 1996 JMPR had concluded no dietary intake concerns would result
from the existing or revised EMRLs. Although the Canada delegation indicated
that a national intake assessment had flagged short-term intake concerns
for children, the Netherlands delegation reported that short-term dietary
intake was estimated at 14% of the ARfD for children based on a recent
assessment. Canada tends to adopt additional uncertainty factors based
on endocrine-disruption concerns
Dr.
Kenneth D. Racke is vice president of the IUPAC Chemistry and the
Environment Division and is Global Regulatory Leader-Global Health,
Environmental Sciences and Regulatory Group at Dow AgroSciences in Indianapolis.
Racke holds a Ph.D. in Entomology from Iowa State and an M.S. in Entomology
from the University of Wisconsin, USA. You can contact him at <[email protected]>.
www.codexalimentarius.net/ccpr34/pr02_01e.htm
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