PESTICIDE RESIDUES IN FOOD - 1983
Sponsored jointly by FAO and WHO
EVALUATIONS 1983
Data and recommendations of the joint meeting
of the FAO Panel of Experts on Pesticide Residues
in Food and the Environment and the
WHO Expert Group on Pesticide Residues
Geneva, 5 - 14 December 1983
Food and Agriculture Organization of the United Nations
Rome 1985
TRIADIMEFON
TOXICOLOGY
Explanation
Triadimefon was evaluated by the 1979 Joint Meeting (FAO/WHO
1980)1 and as no acceptable daily intake (ADI) was allocated at that
Meeting, guideline levels were proposed. At the 1982 Joint Meeting, a
temporary ADI was allocated, and guideline levels were changed to
temporary maximum residue limits.
Further studies were desired on livestock animals for
establishing a dose-response relationship between feed contents and
residues in animal tissues, including realistic feeding levels.
Information was also desired on residue levels in coffee and hope and
in pineapples after appropriate postharvest treatments.
New residue data has been received on triadimefon and its main
metabolite, triadimenol, in fruit, coffee, grains and pineapple
(postharvest). Data have also been provided from feeding experiments,
where cattle and poultry were fed with triadimefon-triadimenol
mixtures. In addition, data have become available from studies on
metabolism in plants and behaviour of the compounds in water and soil.
These data are evaluated in this monograph addendum.
EVALUATION FOR ACCEPTABLE DAILY INTAKE
TOXICOLOGICAL STUDIES
Special Studies on Teratogenicity
Emulsified triadimefon (93.2 percent pure) was administered by
gavage daily to pregnant CD-SD rats on days 6 to 15 of gestation at 0,
10, 30 and 90 mg/kg. Animals were sacrificed on gestation day 20 and
foetuses were examined for gross, soft tissue and skeletal anomalies.
Maternal toxicity, indicated by decreased body weight gains, occurred
at 90 mg/kg. Implantation rates, number of viable foetuses, resorption
rates, litter size, sex ratio and average foetal weight were not
influenced by treatment. Anomalies of the urogenital system, namely
hydronephrosis and distension of the urinary bladder, were noted at
the 30 and 90 mg/kg levels, but the increases were without statistical
significance. A significant number of extra ribs occurred at 90 mg/kg
but other skeletal abnormalities, incompletely ossified and wavy ribs,
were not statistically significant. Thus, the no-effect level from
this study corresponded to 30 mg/kg (Unger et al. 1982).
1 See Annex 2 for FAO and WHO documentation.
Groups of 12 Himalayan rabbits received daily doses by gastric
tube of 0, 10, 30 and 100 mg/kg of emulsified triadimefon from days 6
to 18 of gestation. The dams were sacrificed at day 29 and foetuses,
delivered by Caesarean section, were examined for gross, soft tissue
and skeletal abnormalities.
Only dams treated at 100 mg/kg exhibited symptoms of maternal
toxicity, namely reduced food intake, diarrhoea or reduced stool
volume and swelling or inflammation of the external vagina, with
weight loss during treatment. A slight reduction in maternal weight
gain during treatment at 30 mg/kg was not statistically significant.
At 100 mg/kg, the rate of intrauterine foetal loss and the
male/female sex ratio increased; the latter was possibly associated
with the reduced total number of foetuses. Mean foetal and placental
weights were unaffected and there was no increase in the incidences of
skeletal deformities, malformation or growth stunting of foetuses. The
results of this study suggest 30 mg/kg as the no-effect level for
reproductive toxicity in the Himalayan rabbit (Roetz 1982).
Special Studies on Skin Sensitization
Triadimefon (97 percent pure) did not exhibit dermal sensitizing
properties in guinea pigs when injected intracutaneously and by dermal
patch testing (Iyatomi 1981).
Special Studies on Neurotoxicity
In male mice, strain Bor:CFI(SPF), triadimefon did not prolong
hexobarbital anaesthesia; exhibit anticonvulsant, cataleptic or
analgesic effects; inhibit traction capability, or orientational or
spontaneous mobility at 0, 0.3 or 3.0 mg/kg. At the same doses, male
rats exhibited no cataleptic effects and neuromuscular transmission,
as indicated by electrophysiological techniques, was not significantly
affected (Polacek 1983).
Special Studies on Induction of Liver Enzymes
In vitro, technical triadimefon was a modest inhibitor of both
rat and mouse liver microsomal O-de-ethylation of 7-ethoxycoumarin,
aldrin epoxidation and biphenyl hydroxylation. It caused a spectral
shift characteristic of substrate binding with cytochrome-P450.
When administered daily for seven days to male and female rats,
triadimefon induced hepatic mono-oxygenase activity (aldrin
epoxidation, 7-ethoxycoumarin O-de-ethylation) at 30 mg/kg in males
and 10 mg/kg in females. However, triadimefon did not induce 2- or
4-hydroxylation of biphenyl significantly.
In mice, daily doses of triadimefon induced aldrin epoxidation in
both males and females at 50 mg/kg and 7-ethoxycoumarin O-de-ethylase
caused such induction at 50 mg/kg in males and at 100 mg/kg in females
(Schmidt 1983).
COMMENTS
Studies in rats and rabbits confirmed previous findings that
triadimefon has little or no teratogenic potential. The signs of acute
poisoning indicate central nervous system toxicity, but investigations
on the mechanism of this were inconclusive. In vitro, triadimefon
inhibited hepatic microsomal de-ethylation of 7-ethoxycoumarin, aldrin
epoxidation and biphenyl hydroxylation, and was bound to cytochrome
P-450. In rats and mice fed with triadimefon, induction of
7-ethoxycoumarin de-ethylation and aldrin epoxidation, but not of
biphenyl hydroxylation or cytochrome P-450 level, occurred. These
results confirm previous findings but do not explain either the
treatment-related increase in liver weights or the hyperplastic liver
nodules previously reported in rats and mice. The Meeting agreed to
extend the temporary ADI until 1985.
TOXICOLOGICAL EVALUATION
Level Causing no Toxicological Effect
Mouse: 300 ppm in the diet, equivalent to 40 mg/kg b.w.
Rat: 50 ppm in the diet, equivalent to 2.5 mg/kg b.w.
Dog: 230 ppm in the diet, equivalent to 8.25 mg/kg b.w.
Estimate of Temporary Acceptable Daily Intake for Man
0-0.01 mg/kg b.w.
FURTHER WORK OR INFORMATION
Required (by 1985)
Clarification of the toxicological significance of hepatic
toxicity in rats and mice and of the hyperplastic liver nodules
observed in chronic mouse feeding studies.
Desirable
Observations in humans.
REFERENCES - TOXICOLOGY
Iyatomi, A. Report of acute toxicity. Tokoyo report sheet No. 25
1981 submitted to WHO by Bayer AG. (Unpublished)
Polacek, I. Safety pharmacology study with MEB 6447 on oral
1983 administration. Toxicological Institute, Regensburg, Report
No. R 2428 submitted to WHO by Bayer AG. (Unpublished).
Roetz, R. MEB 6447. Evaluation for embryotoxic effects on rabbits
1982 after oral administration. Bayer AG, Institute for
Toxicology, Report No. 10831 submitted to WHO by Bayer AG.
(Unpublished)
Schmidt, U. Interaction of triadimefon with liver microsomes, studies
1983 on rat and mouse in vivo and in vitro. Bayer Ag,
Institute for Toxicology, Report No. 11812 submitted to WHO
by Bayer AG. (Unpublished)
Unger, T.M., Van Goethem, D. & Shellenberger, T.E. A teratological
1982 evaluation of Bayleton in mated female rats. Midwest
Research Institute, Report No. 324 to Mobay Chemical
Corporation Agricultural Chemical Division submitted to WHO
by Bayer AG. (Unpublished)
RESIDUES
RESIDUES IN FOOD AND THEIR EVALUATION
USE PATTERN
Information on good agricultural practice has been provided to
the Meeting and is summarized in Table 1.
RESIDUES RESULTING FROM SUPERVISED TRIALS
Additional residue data were available from five countries, which
were submitted by the originating manufacturer (Bayer AG) and from two
others through government institutes. Preharvest trials were performed
on 14 commodities and postharvest trials on one commodity. Results
from the field trials are summarized in Table 2. Results are presented
separately for triadimefon and its main metabolite triadimenol.
Pome Fruits
Apples were treated 12 times with triadimefon and no residues
were found two weeks after last treatment. Pears which received the
same application contained residues up to a total of 0.42 mg/kg.
Table 1. Use Patterns of Triadimefon
g a.i./ha No. of treatments Safety interval
in days
Europe (excl. Mediterranean region)
Cereals 125 - 250 1 - 3 28 - 42
Pome fruit 30 - 125 3 - 12 7 - 35
Grapes 50 4 - 8 14 - 35
Cucumbers 30 4 - 8 3 - 14
(field-grown)
15 - 30 4 - 10 3 - 14
(under glass)
Sugar beet 125 2 - 3 35
Hops 125 - 175 2 - 4 14
Europe (Mediterranean region)
Cereals 125 - 250 1 - 2 15 - 30
Pome fruit 40 - 75 4 - 12 7 - 15
Grapes 50 - 75 4 - 10 15 - 28
100 - 200 (Dust) 4 - 8 15 - 28
Cucurbits 25 - 100 4 - 10 7 - 15
Tomatoes 50 - 150 4 - 8 3 - 7
Middle East
Cereals 125 - 250 1 - 2 31 - 35
Pome fruit 40 - 75 4 - 12 14
Peaches 50 - 150 4 - 6 7
Grapes 50 - 75 4 - 10 14 - 28
Mango 100 - 200 4 - 5 28
Cucurbits 25 - 100 4 - 10 3 - 7
Tomatoes 50 - 150 4 - 8 3 - 7
Tobacco 40 - 75 4 - 6 7
Far East
Pome fruit 60 - 100 3 - 6 5 - 10
Grapes 25 2 - 3 6
Mango 50 2 - 4 6
Cucurbits 25 - 35 3 3 - 6
Table 1. (continued)
g a.i./ha No. of treatments Safety interval
in days
Africa
Cereals 125 - 250 1 - 2 21 - 35
Pome fruit 38 4 - 12 7
Grapes 63 4 - 10 7
Beans 125 3 - 6 14
Coffee 100 - 250 2 - 4 7
(protective)
250 - 500 2 7
(eradicative)
Vegetables 63 7 14
Australia, New Zealand
Cereals 125 - 250 1 - 2 28
Pome fruit 55 - 75 3 - 8 14 - 49
Grapes 13 - 38 4 - 10 14 - 28
Cucurbits 25 - 50 4 - 10 3 - 7
South America
Cereals 125 - 250 1 - 2 21 - 35
Pome fruit 40 - 75 4 - 12 14
Grapes 50 - 75 4 - 10 14
Cucurbits 25 - 100 4 - 15 7
Coffee 125 - 250 2 - 4
(protective)
250 - 500 2
(curative)
North America
Grapes 70 - 210 3 14
Pome fruit 140 - 280 3 -
Table 2. Residues of Triadimefon and Triadimenol from Supervised Trials on Fruit and Vegetables
Crop Dose a.i. No. Residue (mg/kg) Country
g/ha Appl. Day Triadimefon Triadimenol
range average range average
Pome fruit
Apple Bayleton spezial 12 7 0.03 0.03 (2) n.d. - 0.06 < 0.06 (2) FRG
5 WP 10 n.d. - 0.05 < 0.03 (2) n.d. - 0.09 < 0.06 (2)
37,5 14 n.d. n.d. (2) n.d. -<0.06 < 0.06 (2)
21 n.d. n.d. (2) < 0.06 - 0.08 < 0.06 (2)
Pears Bayleton spezial 12 7 0.34 0.34 (1) 0.07 0.07 (1) FRG
5 WP 10 0.34 0.34 (1) 0.08 0.08 (1)[
37,5 14 0.35 0.35 (1) 0.07 0.07 (1)
21 0.21 0.21 (1) < 0.06 < 0.06 (1)
Wine Grapes Bayleton spezial 8 14 0.026- 0.13 0.08 (2) 0.038 - 1.6 0.82 (2) FRG
5 WP 28 <0.02 - 0.083 0.05 (2) < 0.05 - 1.6 0.81 (2)
25 - 50 35 <0.02 - 0.047 0.03 (2) < 0.05 - 1.2 0.61 (2)
Must 35 <0.02 - n.d. < 0.02 (2) < 0.05 - 0.20 0.11 (2) FRG
Wine 55/62 <0.02 - n.d. < 0.02 (2) n.d. - 0.11 0.05 (2)
Bayleton 5 WG 8-9 14 n.d. - 0.10 0.05 (4) n.d. - 2.7 0.77 (4)
25 - 50 28 n.d. - 0.09 0.03 (4) n.d. - 2.8 0.77 (4)
35 n.d - 0.08 0.03 (4) n.d. - 3.1 0.84 (4)
Must 35 <0.02 - n.d. < 0.02 (4) n.d. - 0.39 0.1 (4)
Wine <0.02 - n.d. < 0.02 (4) n.d. - 0.27 0.07 (4)
Table Grapes Bayleton 25 WP 1-2 102 - n.d. n.d. (4) n.d. - 0.05 < 0.05 (4) Chile
25 - 60 110
Table 2. (Continued)
Crop Dose a.i. No. Residue (mg/kg) Country
g/ha Appl. Day Triadimefon Triadimenol
range average range average
Black currant Bayleton 5 WP 3-4 2 0.05-0.06 0.06(2) 0.13-0.13 0.13(2) Sweden
40 g
3 37-46 <0.01-0.01 <0.01(5) <0.01-0.03 0.02(5)
4 37-46 <0.01-<0.01 <0.01(5) 0.01-0.03 0.02(5)
Bayleton 5 WP 4 0 0.23-0.43 0.33 0.18-0.21 0.19 Denmark
37.5g 4 15 0.06-0.07 0.06 0.16-0.16 0.16
Strawberries Bayleton 5 WP 3 15 <0.01-<0.01 <0.01(2) <0.01-0.01 <0.02(2) Denmark
50 g
3 18 <0.01-<0.01 0.01(2) 0.01-0.01 0.01(2)
3 25 <0.01-<0.01 <0.01(2) <0.01- 0.01 <0.01(2)
Cucumber Bayleton F5 1 0.02-0.02 0.02(2) <0.02-<0.02 <0.02(2) Denmark
1 3 <0.01-0.01 <0.01(2) <0.02-<0.02 <0.02(2)
Sugar Beet Bayleton 25 WP 3 FRG
125 g/ha
Roots 35 n.d. n.d. (2) n.d. n.d. (2)
Leaves 35 n.d. n.d. (2) n.d. - 0.07 < 0.06 (2)
Fodder Beet Bayleton 25 WP 3 FRG
125 g/ha J
Roots 35 n.d. n.d. (3) n.d. n.d. (3)
Leaves 35 n.d. n.d. (3) n.d. - < 0.06 < 0.06 (3)
Table 2. (Continued)
Crop Dose a.i. No. Residue (mg/kg) Country
g/ha Appl. Day Triadimefon Triadimenol
range average range average
Coffee Bayleton 25 WP 1-2 El
250 - 500 g/ha Salvador
Beans 24-75 n.d. n.d. (9) n.d n.d. (9) India
Pineapple Bayleton 250 EC 1 Ivory
Fruit 25 - 100 ml/1 0 n.d. - 0.07 < 0.05 (2) n.d. - n.d. < 0.06 (2) Coast
Dipping
Peel 0 0.33 - 1.2 0.72 (2) 0.53 - 1.2 0.87 (2)
Total 0 0.04 - 0.25 0.15 (2) 0.06 - 0.20 0.13 (2)
Grapes, Must and Wine
Wine grapes were treated eight or nine times on various
experimental sites in the Federal Republic of Germany. No residues of
triadimefon were found but residues of triadimenol as much as 0.2
mg/kg occurred 35 days after the last treatment. Must and wine
produced from grapes contained no residues of triadimefon, whereas
must and wine contained triadimenol up to 0.39 and 0.27 mg/kg,
respectively.
Results from supervised trials in Chile on table grapes showed no
residues or residues at about the limits of determination.
Berries
Black currants treated three or four times contained total
residues of up to 0.22 mg/kg 15 days after last treatment but no
residues or very low ones 37 days after the last treatment.
Strawberries treated three times contained residues at or about limits
of determination two weeks after last treatment.
Beets
After treatment with three applications on sugarbeets and fodder
beets, beets were harvested after 35 days. No residues were found of
the parent compound and triadimenol was present only at the limit of
determination.
Pineapples
Experiments were performed with postharvest dippings at
concentrations 25 and 100 mg a.i./l, and samples were analysed the
same day. Residues were in the same order of magnitude as residues
evaluated at the 1979 J.M.P.R.
Coffee
Supervised trials on coffee were carried on in El Salvador and
India. No residues of triadimefon or triadimenol were found in beans
harvested 24-75 days after treatment.
Cereals
Several trials have been carried on with applications of
triadimefon on cereal crops. Results are presented in Table 3. In all
trials, plants were sprayed twice with triadimefon 25 W.P. at dosages
from 125 to 250 g a.i./ha. Grains of oats, rye and barley did not
contain residues of triadimefon or triadimenol, whereas grains of
wheat contained up to 0.06 mg/kg triadimefon and 0.15 mg/kg
triadimenol 35 and 42 days after last treatment. Straw from oats, rye,
wheat and barley contained from <0.05 to 1.24 mg/kg triadimefon
(single value) 35 days after last treatment, and the corresponding
figures for triadimenol were from <0.1-1.5 mg/kg. The highest residue
(1.67 mg/kg) of the total of triadimefon and triadimenol was found in
a sample of straw from rye.
Foods of Animal Origin
In a feeding experiment, cattle were fed a 1:1 mixture of
triadimefon and triadimenol equal to a total of 25, 75 and 250 mg/kg
in feed for a period of 28 days. At the end of this period, the
animals were slaughtered and tissues and milk were analysed for total
residues of triadimefon and metabolites. Total residues from tissues
of liver, kidney, muscle and fat and from milk are given in Table 4.
All tissues, except muscle from the 25 mg/kg experiment, had
measurable residues. Average values for three animals within a group
showed an almost linear relationship with feeding level for residues
in a given tissue.
Milk showed a similar relationship. Average residues in muscle
from the three feeding levels ranged from <0.01 to 0.03 mg/kg, fat
from 0.02 to 0.17 mg/kg, liver from 0.08 to 0.74 mg/kg, kidney from
0.36 to 1.29 mg/kg and milk from 0.07 to 0.05 mg/kg (Kruplak &
Weissenburger 1981a).
In another feeding experiment hens (four birds per interval) were
fed daily rations containing equal amounts of triadimefon and
triadimenol at total levels of 10, 25, 75 and 250 mg/kg in feed for 29
days, after which they were slaughtered. All tissues and late-interval
egg samples from each hen treated with 250 mg/kg were analysed for
total residues of triadimefon, including free and conjugated
metabolites. Average residues were as follows, liver 1.11 mg/kg, eggs
0.03 mg/kg; fat 0.10 mg/kg; skin 0.09 mg/kg; gizzard 0.07 mg/kg and
muscle 0.02 mg/kg. Duplicate liver and egg samples from hens fed 10,
25 and 75 mg/kg all showed measurable residues, Liver and egg residues
from hens fed the lowest dose (10 mg/kg) averaged 0.03 and 0.027
mg/kg, respectively. Results from the experiment are presented in
Table 5 (Kruplak & Weissenburger 1981b).
FATE OF RESIDUES
In Water
Using a standardized test, the stability of triadimefon in water
was investigated with thin-layer chromatography and measurement of the
14C-activity of the active ingredient. At pH 3, 6 and 9 and a
temperature at 22°C the half-lives were found to be more than one
year. From an experiment on the stability in water at 45°C the
half-life was calculated to be about eight years (Wilmes 1982).
Table 3 Residues of Triadimefon and triadimenol from Supervised Trials on Cereal Plants
Crop Dose a.i. No. Residue (mg/kg) Country
g/ha Appl. Day Triadimefon Triadimenol
range average range average
Cereals
Oats Bayleton 25 WP 2 FRG
Green Forage 125 - 130 14 n.d. - 0.06 < 0.05 (3) < 0.1 - 0.26 0.15 (3)
28 n.d. - 0.05 < 0.05 (3) 0.1 - 0.31 0.19 (3)
Straw 35 n.d. - < 0.05 < 0.05 (3) < 0.1 - 0.29 0.10 (3)
42 n.d. - < 0.05 < 0.05 (3) < 0.1 - 0.58 0.25 (3)
Ears 14 n.d. n.d. (3) < 0.1 - 0.30 0.18 (3)
28 n.d. n.d. (3) n.d. - 0.30 0.10 (3)
Grain 35 n.d. n.d. (3) n.d. n.d. (3)
42 n.d. n.d. (3) n.d. n.d. (3)
Eye Bayleton 25 WP 2 FRG
Green Forage 125 - 130 14 < 0.05 - 0.20 0.12 (3) 0.11 - 1.5 0.81 (3)
28 0.05 - 0.12 0.08 (3) n.d. - 1.2 0.68 (3)
Straw 35 < 0.05 - 0.24 0.15 (3) 0.12 - 1.5 0.91 (3)
42 0.06 - 0.18 0.10 (3) 0.17 - 1.31 0.81 (3)
Ears 14 < 0.05 - 0.20 0.10 (3) < 0.1 - 0.41 0.28 (3)
28 n.d. n.d. (3) n.d. - 0.33 0.11 (3)
Grain 35 n.d. n.d. (3) n.d. - <0.1 < 0.1 (3)
42 n.d. n.d. (3) n.d. n.d. (3)
Table 3 (Continued)
Crop Dose a.i. No. Residue (mg/kg) Country
g/ha Appl. Day Triadimefon Triadimenol
range average range average
Wheat Bayleton 25 WP FRG
Stems/Straw 125 - 250 14 n.d. - 0.88 0.15 (9) < 0.08 - 0.71 0.39 (9)
28 n.d. - < 0.04 < 0.04 (8) < 0.08 - 0.71 0.29 (8)
35 n.d. - < 0.04 < 0.04 (9) 0.12 - 1.29 0.43 (9)
42 n.d. - < 0.04 < 0.04 (9) 0.15 - 0.86 0.41 (9)
Wheat
Ears/Grain 14 0.093 - 0.35 0.21 (9) 0.10 - 0.59 0.24 (9)
28 n.d. - 0.06 < 0.04 (8) n.d. - 0.18 0.12 (8)
35 n.d. - 0.06 < 0.04 (9) n.d.- 0.10 0.12 (9)
42 n.d. - < 0.04 < 0.04 (9) n.d. - 0.15 < 0.1 (9)
Barley
Green Forage Bayleton EC. 2 8 0.09-0.12 0.10(2) 0.91-1.00 0.96(2) Denmark
25
125
Straw 2 57 <0.02-<0.02 <0.02(2) 0.20-0.25 0.23(2)
Ears 2 41 <0.01-<0.01 <0.01(2) <0.02-<0.02 <0.02(2)
Grain 2 57 <0.01-<0.01 <0.01(2) <0.02-<0.02 <0.02(2)
Table 4 Total Triadimefon Residues in Bovine Tissues and Milk
Feeding Average of total residues (mg/kg) and range ( )
level Liver Kidney Muscle Fat Milk
N=3 N=3 N=3 N=3 N=9
25 mg 0.08 0.36 <0.01 0.02 0.007
(0.07-0.09) (0.30-0.41) (0.02-0.02) (0.004-0.014)
75 mg 0.27 0.54 0.01 0.07 0.024
(0.27-0.29) (0.26-0.79) (<0.01-0.02) (0.05-0.09) (0.014-0.035)
250 mg 0.74 1.29 0.03 0.17 0.050
(0.40-1.00) (0.79-2.27) (0.03-0.04) (0.11-0.21) (0.026-0.077)
Table 5 Total Triadimefon Residues in Poultry and Eggs
Total residues (mg/kg) N = 2
Feeding Liver Eggs (27-28 days)
level
10 mg 0.02 - 0.05 0.02 - 0.03
25 mg 0.08 - 0.09 0.04 - 0.07
75 mg 0.18 - 0.29 0.09 - 0.22
Average of total residues (mg/kg), and range ()
Muscle Fat Liver Skin Gizzard Eggs
250 mg 0.02 0.10 0.11 0.09 0.07 0.93
(0.01-0.02) (0.05-0.15) (0.91-1.41) (0.04-0.20) (0.06-0.09) (0.70-1.19)
In Plants
Rotational crops
Uptake of soil residues by rotational crops has been studied by
Fredrickson & Thornton (1982). Triadimefon-benzene ring-14C was
applied to winter wheat at a dosage equal to 8 oz/acre (ca. 0.5
kg/ha). At 28 days after treatment, the wheat was removed and kale,
beetroots and spring wheat were grown as rotational crops to maturity.
At 119 days after treatment, similar crops were planted and grown to
maturity. Total radiocarbon residues were determined in crops sampled
at various intervals, including harvest. Residues were highest in
wheat forage (0.12 mg/kg) and wheat heads (0.10 mg/kg) in the 28-day
rotational crops. Residues in the 28-day kale crop ranged from
0.02-0.08 mg/kg, while residues in beetroots were less than 0.01
mg/kg. Residues in the 119-day rotational crops were slightly lower.
The distribution of compounds with carbon radioactivity in
119-day rotational crops of kale, beet tops and wheat straw was
investigated by thin-layer chromatography. As concentrations were low,
near the limit of determination, a final identification was not
possible, but it was tentatively concluded that mainly triadimenol but
also triadimefon and 4-chlorophenol were present in the 119-day
rotational crops. In wheat straw, about 30 percent of the carbon
radioactivity came from free triadimenol, triadimefon and
4-chlorophenol and, in addition, 20 percent came from conjugated
triadimenol and 4-chlorophenol.
In grapes
In an experiment on uptake and translocation of triadimefon in
grape plants 14C-triadimefon was applied on the leaf surface and its
movement observed by autoradiography. The active ingredient moved
rapidly into the uppermost epidermal layers, from where it was
absorbed into the tissues. As a result, washing with water only 45
min. after foliar application could not recover more than half of the
applied dose. When applied to young, unlignified stem tissue, the
active ingredient also was transmitted into the leaves above.
Translocation from the vascular system to the adjacent tissue was more
pronounced in young leaves than in old ones (Kraus 1981).
In barley
Shoots of barley (stage 6) grown in a greenhouse were treated
with 14C-triadimefon at a dosage of 500 g a.i/ha, which is four times
higher than the recommended dose at 66 days after treatment (stage
10), plants were harvested and analysed for residues of triadimefon
and its metabolites, free as well as conjugated. The results from the
experiment are presented in Table 6 (Rouchaud et al. 1982). In a
supplementary study the same authors investigated the metabolism of
triadimefon in grain and straw of ripe barley treated with
14C-triadimefon at same time and dosage as in the above-mentioned
study and with a second treatment 76 days after first treatment, with
Table 6 Residues of Triadimefon and Metabolites in Barley
Green plants Grains Straw
Application: (stage 10) (stage 11.4) (stage 11.4)
Compound 1 x 500 g 2 x 500 g 2 x 500 g
% of total mg/kg % of total mg/kg % of total mg/kg
radioactivity radioactivity radioactivity
in plant in plant in plant
Triadimefon, free 9.7 1.00 6.0 0.12 2.3 0.70
Triadimenol, free 20.3 2.10 9.5 0.19 5.4 1.61
Triadimenol, conjug. 8.0 0.80 3.5 0.07 0.3 0.10
4-chlorophenol, conjug. 35.1 1.58 15.5 0.13 3.8 0.49
Residues insolub, in 13 61 84
acetone-water (3.3+1)
a dosage equal to that of the first treatment. The ripe plants were
harvested 42 days after last treatment and grains and straw were
analysed. The results from this investigation are also presented in
Table 6 (Rouchaud et al. 1981).
In Wheat
Plants of spring and winter varieties of wheat were sprayed with
14C-triadimefon at a dosage equivalent to 8 oz a.i./acre (ca. 0.5
kg/ha). Forage samples were taken 0, 7, 14 and 28 days after
treatment. The wheat was harvested 84 and 74 days, respectively, after
treatment. Analytical results were generally parallel for the two
varieties. By an exhaustive extraction procedure, mainly methanol and
methanol/water mixtures, 95.7 to 99.8 percent of the radioactive
residues were extracted. Triadimefon was metabolized with initial
half-lives of 8 and 18 days for spring and winter wheat, respectively.
Residues in forage and straw were converted primarily to triadimenol
plus a number of minor apolar metabolites and their polar glycoside
conjugates. Identification was obtained for 81.6 percent of the total
activity. Residues in grains were low (0.8 mg/kg) (Morgan & Lenz
1982).
Metabolism
The ratio of the two diastereomeric forms of triadimenol,
produced by the reduction of triadimefon in various fungi, was
studied. The reduction of triadimefon in fungi seems to be a
concentration-dependent process, the virtual irreversibility of which
has been proved. Not only the degree of triadimefon reduction, but
also the ratio of the triadimenoldiastereomers produced, was
characteristic for each of the fungal species. A direct correlation
between the production of the more active diastereomeric form and the
sensitivity of the fungal species to triadimefon was observed
(Gasztonyi 1981).
National Maximum Residue Limits
The following national maximum residue limits (MRLs) for
triadimefon and triadimenol were reported to the Meeting.
Country Crop Maximum residue Preharvest
limit interval
(mg/kg) (days)
The Netherlands Apple 0.1 14
Grain, milk and milk 0.05 grain: 42
products, meat and
meat products
Sweden Fruit and vegetables 0.5 28 days
cucumber: 4 days
United States Wheat grain 1 21
Wheat, green forage 15 21
Wheat straw 5 21
Barley grain 1 21
Barley, green forage 15 21
Barley straw 5 21
Meat, fat and meat by- 1
products of cattle,
goats, horses and sheep
Eggs, milk, meat, fat 0.04
and meat by-products of
poultry and pigs
Wheat, milled fractions 4
(except flour)
Barley, milled fractions 4
(except flour)
APPRAISAL
In response to requests from the 1979 Meeting, information was
received on residues of triadimefon and its main metabolite,
triadimenol, in animal tissues, milk and eggs after feeding studies on
cattle and hens. Residue data were also received on a large number of
supervised trials on fruit, beets, coffee and cereals.
Residue data from trials on apples, grapes and berries
supplemented those received at the 1979 Meeting and confirmed the
residue limits recommended. New data from trials on preharvest
treatments of coffee, pears and fodder beets and postharvest treatment
of pineapples enabled the Meeting to recommend residue limits for
these commodities.
At the 15th Meeting of the Codex Committee on Pesticide Residues
a need was expressed to raise residue limits for grains, and
especially for barley, and also for barley and wheat straw. The
Meeting has received new data from trials on cereals, including
residue data on grains and straw from barley and wheat. This new data
did not, however, support raising the limits for grains of barley,
oats and rye, whereas some data would support raising the limits for
wheat grains. The data received did not support higher limits for
straw.
Data from feeding studies on cattle and hens were carried out at
unrealistically high feeding levels, but even the lowest of these
levels (25 mg/kg in feed for cattle and 10 mg/kg in feed for hens)
showed that residues in muscle, fat and milk from cattle and liver and
eggs from hens were well within the residue limits recommended by the
1979 Meeting. As the experiment has demonstrated an almost linear
relationship with the feeding levels for residues in tissues, the
residues would be expected to be much lower from the use of feed with
lower and more realistic feeding levels.
A rotational crop study indicated the presence of triadimefon and
mainly triadimenol in subsequent crops, especially in wheat grown in
fields treated with triadimefon in which the benzene ring was marked
with 14C.
A study was made on uptake and distribution in grape plants
through the foliar surface, which confirms previous studies on other
plants. Studies have also been made on metabolism in barley and wheat,
which confirm that triadimenol is the main metabolite in plants, but
also revealed the presence of glycoside conjugates of triadimenol and
4-chlorophenol in green plants, grains and straw.
RECOMMENDATIONS
The Meeting examined residue data from supervised trials on a
number of crops. From these data the Meeting was able to confirm
existing residue limits and recommended new temporary maximum residue
limits below which residues are likely to occur, when triadimefon is
used according to present practice and the reported intervals are
observed. The limits refer to the sum of the parent compound
triadimefon and its major metabolite triadimenol.
Since MRLs now have been recommended for the major pome fruits at
a level of 0.5 mg/kg, the Meeting proposed that this figure could be
extrapolated to the whole commodity group and a group MRL recommended.
Crop Temporary Preharvest intervals
MRL on which recommendations
are based (days)
Pome fruit 0.5 14
Pineapple 2 postharvest
Fodder beet 0.1** 35
Fodder beet leaves 0.1** 35
Poultry meat 0.1**
Wheat 0.2 (increase 35
from 0.1)
** Level at or about the limit of determination.
REFERENCES - RESIDUES
Fredrickson, D.R. & Thornton, J.S. Residues in rotational crops
1982 following treatment of a target crop with Bayleton-14C.
Mobay report No. 80 606 submitted to FAO by Mobay Chemical
Corporation. (Unpublished)
Gasztonyi, M. The diastereometric ratio in the triadimenol produced by
1981 fungal metabolism of triadimefon, and its role in fungicidal
selectivity. Pestic. Sci., 12: 433-438.
Kraus, P. Studies on uptake and translocation of Bayleton in grape
1981 plants. Bayer Pflanzenschutz-Nachr. 34: 197-212.
Kruplak, J.F. & Weissenburger, B. Effect of feeding Bayleton and the
1981a metabolite KWG 0519 (BaytanTM) to dairy cattle - Total
residue. Mobay report No. 69 930 submitted to FAO by Mobay
Chemical Corporation. (Unpublished)
Kruplak, J.F. & Weissenburger, B. Effect of feeding Bayleton and the
1981b metabolite KWG 0519 (BaytanTM) to poultry - Total residue.
Mobay report No. 80 281 submitted to FAO by Mobay Chemical
Corporation. (Unpublished)
Morgan J.G. & Lenz, M.F. Metabolism of Bayleton in wheat. Mobay report
1982 No. 80 293 submitted to FAO by Mobay Chemical Corporation.
(Unpublished)
Rouchaud, J., Moons, C. & Meyer, J.A. The products of metabolism of
1981 14C-triadimefon in the grain and in the straw of ripe
barley. Bull. Environ. Contam. Toxicol., 27: 543-550.
Rouchaud, J., Moons, C. & Meyer, J.A. Metabolism of 14C-triadimefon
in
1982 barley shoots. Pestic. Sci., 13. 169-176.
Wilmen, R. Fate/behaviour of crop protection products in water. Bayer
1982 AG, PF-A/CE-PIQ-ENA. Report submitted to FAO by Mobay
Chemical Corporation. (Unpublished)
See Also:
Toxicological Abbreviations
Triadimefon (Pesticide residues in food: 1979 evaluations)
Triadimefon (Pesticide residues in food: 1981 evaluations)
Triadimefon (Pesticide residues in food: 1984 evaluations)
Triadimefon (Pesticide residues in food: 1985 evaluations Part II Toxicology)