P A N U P S
Pesticide Action Network
April 14, 1995
High OP Residues Found in UK Carrots
Research findings announced by the U.K. Ministry of
Agriculture (MAFF) on January 18, 1995, have shown that
unexpectedly high residues of organophosphate (OP)
insecticides occur in some carrots. The Ministry has
announced restrictions on the use of OPs to restore the
margins of safety.
A change of sampling technique in which carrots were analyzed
individually has shown that 1-2% of carrots tested contain OP
residues up to 25 times higher than expected. Past monitoring
had been based on the analysis of composite (blended) samples
of carrots in accordance with standard methods of sampling.
Residue levels of individually tested carrots varied by large
factors, from below the level of detection to far in excess
of the maximum residue limit. Ministry officials are at a
loss to explain how these high levels have occurred.
OPs are used on U.K. carrots primarily to control the carrot
root fly (Psila rosae). The OPs chlorfenvinphos, phorate,
triazophos, quinalphos and primiphos-methyl have been widely
used over the last 25 years in Britain to control the
season's first and possibly second generation larvae which
attack the root. In the mid-1960s, carrots received an
average of two applications per season (one OP and one
organochlorine). Since then there has been a steady increase
in the area of carrots treated with OPs. In 1966, a total of
3, 000 hectares were treated with one or two pesticides,
while by 1991 virtually the entire U.K. carrot crop was
treated with up to seven different OPs.
Topping, the practice of cutting the top 2-3 mm of the
carrot, together with peeling removes about 4/5 of residues
of chlorfenvinphos, primiphos-methyl, quinalphos and
triazophos. Data on phorate residues after topping and
peeling are not available. This is problematic since phorate
is a systemic OP and its residues may be found throughout the
The U.K. Advisory Committee on Pesticides (ACP), which
advises government ministers, considers that although there
is no immediate threat to human health, "margins of safety
have been eroded to a level where action is required to
restore them." The Committee nevertheless made a number of
recommendations for urgent consideration:
-- The Working Party on Pesticides Residues should carry out
further analyzes to extend the current available database to
confirm the frequency with which high residues of OPs occur
in individual carrots.
-- There should be early discussions with the agrochemical
manufacturers, carrot growers and retail/consumer interests
to explain the findings. (This has been carried out.)
-- All information on resistant varieties, crop covers and
cold storage of carrots should be collated in order to
consider cultural methods of pest control.
-- The number of OP applications per year should be amended
to a maximum to three (down from a possible maximum of nine).
-- The possible use of alternative carbamate pesticides
(carbofuran and carbosulfan) are suggested.
The U.K. Agriculture Minister accepted all of the
recommendations made by the Advisory Committee on Pesticides.
Commenting on the MAFF findings and ACP recommendations, the
Pesticides Trust (U.K.) finds that the unexpected residue
results raise further issues requiring urgent attention:
-- It is not clear whether the recently recommended three
applications of OPs per year would also produce individual
carrots with occasionally high residue levels. OP pesticides
can cause adverse neurological effects in both the long and
short term. Their use must be immediately reduced to protect
those who work with pesticides as well as consumers. Levels
of the carbamate residues carbosulfan and carbofuran in
carrots remain uncertain. Is chemical pest control for
carrots currently sustainable?
-- Research into non-chemical pest control for carrots should
be stepped up. These could include the use of resistant
varieties, rotation, crop covers, and a change in harvesting
strategy. An "IPM committee" of the MAFF should be
established which allow such recommendations to be carried
-- What are the implications of the change in testing methods
for all raw produce? It is not clear if these residue
discrepancies are restricted to carrots. The Pesticides Trust
therefore calls for the sampling techniques for all produce
and pesticide groups to be re-assessed on an individual
Source: Pesticides News, March 1995.
Contact: The Pesticides Trust, Eurolink Centre, 49 Effra
Road, London SW2 1BZ, UK; phone (44-71) 274 8895; fax (44-71)
274 9084; email firstname.lastname@example.org.
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