QUINTOZENE JMPR 1973
Explanation
This soil fungicide was evaluated at the 1969 Joint Meeting
(FAO/WHO, 1970). A temporary acceptable daily intake of 0-0.001 mg/kg
bw was established with the requirement that the results If
carcinogenicity studies on two species of animal should be made
available by June 1973. Studies to explain the cause of growth
depression and the effects on bone marrow and liver in dogs and
studies on the metabolism of quintozene and on the activity of the
metabolites, particularly pentachloroaniline were requested.
It is noted that most recent studies on this fungicide have given
emphasis not only to quintozene per se, but also to some related
chemical substances and impurities, which may be present in the
technical product, especially hexachlorobenzene.
Further data made available are summarized in this monograph
addendum.
EVALUATION FOR ACCEPTABLE DAILY INTAKE
Biochemical aspects
Absorption, distribution and excretion
Groups of three cows were administered quintozene orally at
dosage levels equivalent to 0, 0.1, 1 and 10 ppm in the diet for 12-16
weeks. One cow received 1000 ppm for one month. Milk, biopsy and
autopsy samples of fat and autopsy samples of other tissues were
analysed. The results of the analyses using a highly sensitive method
demonstrated that tissue storage of quintozene and the principal
metabolites did not occur, nor were they excreted in milk (Borzelleca
et al., 1971).
No quintozene, pentachloroaniline or methyl pentachlorophenol
sulphide were detected in milk from a cow administered quintozene
orally at a level equivalent to 5 ppm in the diet for three days.
Forty-five per cent. of the administered dose was eliminated as
pentachloroaniline within four days of the last dose (St. John et al.,
1965).
Quintozene was administered orally to mice as a solution in corn
oil/acetone mixture. Only low serum quintozene levels (< 1 ppm) were
found, the highest levels being found two to six hours after dosing.
Analysis of tissues after single or multiple doses of quintozene
showed that the highest concentrations occurred two to six hours after
dosage but these fell rapidly. Pentachloroaniline was also found but
the highest concentration of this occurred in bile; this possibly
accounts for the high concentration of this metabolite in faeces.
Methyl pentachlorophenol sulfide was also found in tissues and the
high concentration in liver two hours after dosage suggests that
quintozene is rapidly converted to this metabolite, which is then
rapidly excreted. Quintozene and its metabolites did not build up in
tissues on repeated dosage. No data were presented on the
hexachlorobenzene content of tissues. In pregnant mice more methyl
pentachlorophenol sulfide passed the placenta than the other compounds
and high concentrations were found in the fetus and uterus (Courtney,
1973).
Biodegradation
The major metabolite of quintozene in mice is pentachloroaniline.
After repeated dosage the urinary content of this increases in male
but not in female animals. Methyl pentachlorophenol sulfide is
excreted mainly in the conjugated form (Courtney, 1973).
TOXICOLOGICAL STUDIES
Special studies on carcinogenicity
A group of 10 male and 10 female mice was painted twice weekly
for 12 weeks with an 0.3% solution of quintozene in acetone. A similar
group of control animals was painted with acetone. All mice were then
painted with croton oil for 20 weeks and surviving mice were killed
after a further 20 weeks without treatment. Papillomata appeared in
test animals after five to eight weeks treatment with croton oil and
became more numerous until 5-10 weeks after cessation of treatment,
after which some of them regressed. One test animal was found to have
a single squamous cell carcinoma at the end of the experiment (Searle,
1966).
Special studies on teratogenicity
An unstated number of C57 black/6 mice received up to 500
mg/kg/day quintozene (containing 1% hexachlorobenzene) in 0.1 ml of
oil on days 7-11 of gestation and were killed and examined on day 19.
Fetal weight and mortality were unaffected but the incidence of eye
abnormalities which normally affect 107 of young was increased. In
addition there was a 49% increase in renal agenesis and cleft palates
occurred in some litters from treated mothers. Dosage levels of 100
and 200 mg/kg/day were without ill-effect.
Quintozene in corn oil/acetone was administered to an unstated
number of random bred CH1 mice from day 7-17 of gestation. Fetal
mortality was unaffected at the 200 mg/kg dosage level but animals
receiving 500 mg/kg produced young with a high incidence of cleft
palate; kidney abnormalities were not found.
An unstated dose of quintozene of 99% purity was administered
orally each day to random bred CB rats from days 7-18 of gestation.
Animals were killed on the nineteenth day. No effect on maternal
weight, liver weight, weight of fetuses, fetal viability and
morphological development was seen (Courtney, 1973).
Groups of at least 20 pregnant Charles River rats were
administered orally by gavage 8, 20, 50 or 125 mg/kg of quintozene
dissolved in corn oil once daily on days 6-15 of gestation. Negative
control groups received corn oil or were intubated without being
administered vehicle and a positive control group received
chlorcyclizine. No abnormalities were found which could be attributed
to quintozene treatment in the numbers of corpora lutea,
implantations, dead and resorbed fetuses, viable fetuses, fetal
weights and sex or in skeletal or soft tissue malformations (Jordan
and Borzelleca, 1973).
Special studies on metabolites
An unstated number of C57 black/6 mice received up to 500 mg
pentachloroaniline/kg in 0.1 ml oil on days 7-18 of gestation and were
killed and examined on day 19. Maternal weight was decreased and fetal
mortality increased at the 100 mg/kg dosage level but not at higher
levels.
Pentachloroaniline in corn oil/acetone mixture was administered
to an unstated number of random bred CHl mice from days 7-17 of
gestation. Fetal mortality and development were unaffected at the 200
mg/kg dosage level.
An unstated dose of pentachloroaniline was administered orally to
random bred CB rats from days 7-18 of gestation. Animals were killed
on the nineteenth day. Maternal weight was depressed but all other
indices were normal (Courtney, 1973).
Acute toxicity
No further data.
Short-term studies
No further data.
Long-term studies
No data are yet available.
Comments
Further studies have confirmed that quintozene is absorbed from
the gastrointestinal tract and rapidly excreted, the main metabolites
being pentachloroaniline and methyl pentachlorophenol sulfide. The
latter was found at higher concentrations than other metabolites in
the fetuses of mothers exposed to quintozene.
Studies have shown that pentachloroaniline has no teratogenic
activity. An increased number of eye abnormalities, cleft palates and
renal agenesis was reported in one mouse strain and cleft palates in
another strain in teratogenicity studies in which 300 mg/kg doses of
quintozene were administered, Lower dosage levels produced no
abnormalities in mice and no teratogenic abnormalities were found in
studies on rats. The reason for this difference has not been
established.
No studies have been carried out to explain the effects reported
to occur in dogs and no other studies on pentachloroaniline have been
made available. It was noted that long-term feeding studies in rats
and mice are in progress and that results may soon be available. The
Meeting considered that a temporary acceptable daily intake could be
set for a further two years.
TOXICOLOGICAL EVALUATION
Level causing no significant toxicological effect
Rat: 25 ppm in diet equivalent to 1.25 mg/kg bw
Estimate of temporary acceptable daily intake for man
0-0.001 mg/kg bw
RESIDUES IN FOOD AND THEIR EVALUATION
Purity of quintozene
Detailed gas-chromatographic analyses of technical quintozene,
including its chemically related impurities, have been established
(Olin Mathieson Co., 1973). The ranges covered by 10 samples from five
different manufacturers are given as follows:
Quintozene (PCNE) : 88.4-98.6
Tetrachloronitrobenzene (TCNB) : 0.3-3.9
Hexachlorobenzene (HCB) : n.d.-10.8
Pentachlorobenzene (PCB) : n.d.-1.2
Others, high boilers : n.d.-0.6
The high boiling fraction is identified, from one producer, as mainly
consisting of tetrachlorodinitrobenzene, whereas attempts to detect
any tetra- or octa-chlorodibenzo-p-dioxin have proved negative, within
a detection limit of 0.05 ppm (Griffith and Thomas, 1972).
From many additional samples analysed (CXPR, 1973) it is
indicated that production procedures which favour a minimum content of
MB, may give rise to increased amounts of pentachlorobenzene. Thus,
three samples containing less than 0.1% HCE, contained up to 3.6%
pentachlorobenzene.
Use pattern
While no significantly different use patterns have been
described, some additional information on already established uses has
been received.
Residues resulting from supervised trials
Kuchar et al. (1973) have supplied further data on residues found
after field trials, setting out the analytical findings individually
for quintozenep pentachlorobenzene and hexachlorobenzene (HCB), as
well as for the metabolites pentachloroaniline (PCA) and methyl
pentachlorophenyl sulfide (MPCPS). This information is summarized in
Table 1 reporting the maximum residues only. The results indicate that
total residues resulting from approved uses largely conform to the
temporary residue limits recommended by the 1969 meeting, the
exception being peanut kernels for which the composite residues
following recommended use patterns suggest 2 ppm as a more realistic
level.
From information presented by the Netherland delegation to the
sixth session of the Codex Committee on Pesticide Residues and later
directly to the Joint Meeting, it has become evident that there exists
an established and definite need for quintozene to control prevailing
fungi complexes of Botrytis and Sclerotinia species which in some
countries has justified a yearly preplanting soil treatment of 3 g
a.i. per m2. Results from supervised trials (see Table 2) demonstrate
that such registered use regularly gives residues in lettuce heads,
which, however, only occasionally exceed 3 ppm.
Results of analysis show that quintozene is not evenly
distributed in the harvested crop. A three to four fold higher
concentration is found in the outer leaves of individual heads than in
the remaining inner parts. This leads to the conclusion that a major
part of the residues results from vapour transfer from the soil under
closed glasshouse conditions rather than by way of absorption through
the roots.
Fate of residues
In plants
The above residue data confirms a slight systemic uptake from
soil into plants. Residues of impurities in the technical product
(i.e. HCB and PCB) and the metabolites formed in soil and/or plants
(i.e. PCA and MPCPS) usually comprise the greater part of total
residues. A significant increase of PCB relative to HCB compared to
the ratios in technical quintozene is noted simultaneously with the
formation of PCA and MPCPS.
TABLE 1. RESIDUES OF QUINTOZENE, METABOLITES AND IMPURITIES IN VARIOUS CROPS
Crop Application Quintozone PCB HCB PCA NPCPS
rate
Beans, Lima 0.5-1.5 lb/ 0.029 n.d. n.d. 0.014 n.d.
acre
Beans, Snap 2 lb/acre n.d. n.d. n.d. n.d. n.d.
Cabbage 15 lb/acre 0.004 n.d. 0.001 n.d. 0.015
Peanuts 10 lb/acre 0.015-0.269 0.002-0.148 0.012-0.278 0.028-0.324 n.d.-0.42
Peanut hulls 10 lb/acre 0.51-0.98 0.04-0.109 0.03-0.310 0.34-0.90 0.03-0.27
Peas 1.5 lb/acre 0.007 n.d. n.d. n.d. n.d.
Potatoes 25 lb/acre 0.004 0.044 0.008 0.025 0.013
Potatoes, 25 lb/acre 0.002 0.040 0.007 0.020 0.008
peeled
Potatoes, 25 lb/acre 0.026 0.080 0.018 0.066 0.057
peel only
Potatoes 50 lb/acre 0.024 0.059 0.014 0.031 0.033
TABLE 2. QUINTOZENE RESIDUES IN GLASSHOUSE LETTUCEa
(Treatment: 3 g a.i./m2, before planting)
13
Weeks after planting: 9 10.5 12 (Harvest)
Exp. 1
Weight of lettuce head (g) 5.4-5.7 13.8-15.2 36.2-39.6 75.8-92.6
Quintozen (ppm) 2.3-2.7 1.7-2.2 1.7-3.5 2.0-2.7
Exp. 2
Weight of lettuce head (g) 17.8-17.9 37.0-37.2 85.3-92.7 162.5-168.2
Quintozene (ppm) 2.2-2.7 2.5-3.2 1.0-2.9 1.2-2.2
a Each figure represents average of four replicates.
Data corrected for non-treated controls.
A definite uptake of quintozene and derivatives by both potatoes
and carrots grown in treated soils is demonstrated in the first year
of a two-year study by Beck and Hansen (1973b), the results of which
is summarized in Table 3. A second-year residual uptake is further
evident in carrots (a total of 0.59 ppm), but not detectable in
potatoes. The sum of impurities and metabolites constituted up towards
507 of total residues in those studies with PCA and MPCPS as the major
components.
TABLE 3. TWO-YEAR STUDY OF QUINTOZENE UPTAKE IN CARROTS AND POTATOES
(from Beck & Hansen, 1973b)
Date of Residues in ppm
Treatment Harvest Quintozene Tecnazene PCB HCB PCA MPCPS
Carrots (60 kg a.i./ha
per treatment)
May 1970 September 1970 1.00 n.d. 0.02 0.03 n.d. n.d.
May 1970 September 1971 0.45 0.02 0.09 0.03 0.06 0.04
May 1970 +
May 1971 September 1971 2.02 0.06 0.07 0.07 0.11 0.07
Potatoes (60 kg a.i./ha
per treatment)
May 1970 October 1970 0.20 0.01 0.02 0.03 0.03 0.04
May 1970 September 1971 n.d. n.d. n.d. n.d. n.d. n.d.
May 1970 +
May 1971 September 1971 0.20 0.01 0.03 0.04 0.05 0.05
In animals
Results of experimental feeding of residual quintozene to rats,
dogs and cows have been published (Borzelleca, 1971). No quintozene
could be found in tissues in these studies; neither could quintozene
be identified in milk from cows receiving 0.1-10 ppm in rations.
Pentachloroaniline and methyl pentachlorophenyl sulfide were found in
tissues as metabolites of quintozene. The studies confirmed an
apparent lack of metabolism of hexachlorobenzene and
pentachlorobenzene which were stored in tissues in concentrations
reflecting the level of these impurities in the technical quintozene.
Results from the feeding of cows at the 1 ppm and 10 ppm level are
summarized in Table 4. Only HCB (and PCD at the 10 ppm level) residues
was noticeable in the milk.
In soil
The apparent high persistence of quintozene in soils has been
confirmed by Beck and Hansen (1973a) through laboratory experiments,
supplemented by a soil sampling programme from potato fields which had
been treated intermittently through the proceeding 5 to 11 years. An
average half-life of 14 months was calculated from 22 field samples.
Quintozene losses from three California soils (fine sandy loam,
and clay soil and peaty mulch) are described by Wang and Broadbent
(1972) as following first-order reactions with halflives from 4.7-9.6
months. These authors further find evidence that volatilization is of
major significance in accounting for the losses of the compound. The
possibility of losses of quintozone to the atmosphere from soil under
field conditions is also described by Caseley (1968).
Degradation of quintozene in soils through microbial and/or
chemical processes is further confirmed as important. Chako et al.
(1966) found that eight soil fungi and eight actinomycetes, grown in
nutrient media, degraded PCNB. Streptomyces aureofaciens reduced the
largest quantity of PCNB, producing pentachloroaniline (PCA).
Nakanishi and Oku (1969) and Kaufmann, (1970) also demonstrated in
addition to PCA, methylthiopentachlorobenzene (MPCPS) as a microbially
produced metabolite. In the laboratory experiments by Beck and Hansen
(1973a) evidence was given that not only PCA and MPCPS, but also
pentachlorobenzene (PCB) could be produced from quintozene in soils.
From the above-mentioned soil sampling programme (Beck and Hansen
(1973a)) average content of quintozene plus impurities and metabolites
was found as shown in Table 5. The highest individual level was a
total of 28.8 ppm found in a field which had been treated three times
within five years with 30-60 kg a.i./ha, the last time one year before
sampling.
TABLE 4. RESIDUES IN COW TISSUES AND MILK AFTER FEEDING QUINTOZENEa
AT THE RATE OF 1 ppm AND 10 ppm IN THE RATION
For 12 weeks 8 weeks
Fat (abdom.) Sk. Muse. Liver Kidney Milk
PCNB 1 ppm n.d. n.d. n.d. n.d. n.d.
10 ppm n.d. n.d. 0.031 n.d. n.d.
TABLE 4. (cont'd)
For 12 weeks 8 weeks
Fat (abdom.) Sk. Muse. Liver Kidney Milk
PCA 1 ppm 0.005 n.d. n.d. n.d. n.d.
10 ppm 0.499 0.018 n.d. 0.043 0.006
MPCPS 1 ppm 0.017 n.d. n.d. n.d. n.d.
10 ppm n.d. n.d. n.d. 0.020 n.d.
PCB 1 ppm n.d. n.d. n.d. n.d. n.d.
10 ppm 0.001 n.d. n.d. n.d. n.d.
HCB 1 ppm 0.046 0.008 n.d. 0.001 0.003
10 ppm 0.618 0.015 n.d. 0.005 0.015
a Composition of technical Qintozene: PCNB: 97.8%, HCB: 1.8%,
PCB: <0.1% and TCNB: 0.4%
TABLE 5. RESIDUES OF QUINTOZENE AND RELATED COMPOUNDS
IN SOIL PROM 22 PREVIOUSLY TREATED FIELDS
Treated 1-5 times Treated 1-4 times
until 3 years before until 1 or 2 years
sampling before sampling
Average (range) -ppm Average (range) - ppm
Quintozene (PCNB) 5.44 ppm (0.01-12.8) 8,41 ppm (1.47-25.3)
Tecnazene (TCNB) 0.09 ppm (n.d-0.18) 0.12 ppm (0.03-0.28)
PCB 0.37 ppm (0.003-0.84) 0.32 ppm (0.16-0.77)
HCB 0.35 ppm (n.d.-0.53) 0.41 ppm (0.17-0.94)
PCA 2.11 ppm (0.01-4.10) 1.28 pp. (0.28-3.31)
MPCPS 0.38 ppm (n.d.-1.07) 0.29 ppm (0.03-0.73)
(From Beck and Hansen, 1973a)
Residues in food commodities in commerce
Quintozene analyses have been included in regular market sample
programmes for pesticide residues in two Scandinavian countries
(Voldum-Clausen, 1973; Westöö and Norén, 1973). In the one country
during the years 1969 to 1972 quintozene was found in 48% of carrots,
49% of potatoes and 43% of lettuce in a total of 454 samples. In the
other country 34%, 46% and 14% of the samples of lettuce, parsley and
carrots were found positive respectively.
These programmes comprised food items of both domestic and
foreign origin. In the case of the domestic products, quintozene
residues in potatoes, parsley and lettuce are the result of
intentional applications, whereas residues in carrots are presumed to
be unintentional, resulting from uptakes from previously treated soils
(Beck and Hansen, 1973a and 1973b).
Quintozene residues in lettuce were similarly reported by the
Netherland delegation to the sixth session of the Codex Comittee on
Pesticide Residues, 1972. Surveys in that country had indicated that
the frequency of positive samples was significantly higher during the
season of glasshouse growing (61% positive from January to April) than
during summer months (32.5% positive from May to June) (CCPR, 1972).
Residue levels in these three surveys were generally below 3 ppm
with the exception of only a few individual lettuce samples.
Methods of residue analysis
Gas-chromatographic methods which allow the determination of
quintozene and its individual impurities and metabolites have been
described by several authors (Kilgore and White, 1970; Collins et al.,
1972; Beck and Hansen, 1973 and Kuchar et al., 1969). The method
described by the latter authors determine PCNB, PCB, HCB and PCA in
animal tissues, blood, bile and urine with a determination limit of
0.005 ppm for each of the compounds and with average recoveries
ranging from 84 to 1077. For MPCPS it was established that recoveries
of 87-105% were obtained at the 0.1 ppm level. Their method uses
extraction with acetonitrile and partitioning into hexane followed by
GLC with electron capture detector.
Baker and Flaherty (1972) have adapted an earlier multiresidue
method for chlorinated pesticides (de Faubert Maunder et al. (1964))
for the determination of quintozene in tomatoes, lettuces and bananas,
as representative products on which quintozene may be used. It
consists of extraction with hexane, partitioning with
dimethylformamide and column chromatographic clean-up on alumina.
Quantitative determination using electron capture gas-chromatography
may be supplemented by a confirmatory chemical test for quintozene
based on reduction to PCA, which is then determined by GLC. This
method shows recoveries of 83-94% at the 0.005-0.1 ppm level in
tomatoes, 75-103% for 0.01-5.0 ppm in bananas and 90-108% for 0.01-5.0
ppm in lettuce.
National tolerances
Some national tolerances reported in 1969 (FAO/WHO, 1970) have
been changed and new tolerances have been established. The following
is a list of national tolerances available to the Meeting.
Federal Republic Lettuce 0.3 ppm
of Germany
Oil Seeds 0.03 ppm
Cabbage 0.02 ppm
Bananas, without peel)
Other vegetable foods) 0.01 ppm
Netherlands and Fruits and vegetables,
Belgium except potatoes 1.0 ppm
Leafy Vegetables 3.0 ppm
United States of Cotton-seed 0.1 ppm as negl.
America residue
Others Originally on "no
residue basic".
At present under
review
German Democratic Potatoes 5.0 ppm
Republic
Potatoes, peeled 0.5 ppm
Cabbage 0.3 ppm
Switzerland Lettuce, wheat 1.0 ppm
Cereal products, 0.1 ppm
flour, bakery
products, etc.
Appraisal
Since the evaluation of quintozene in 1969 further information
has become available on several of the questions which were raised.
More detailed information has been received on technical
quintozene and its impurities. Depending on the production procedure
varying amounts of impurities may be formed. Dominant are
hexachlorobenzene (levels ranging from (< 0.1 to 10.8%),
pentachlorobenzene (from (< 0.1 to 3.6%) and tetrachloronitrobenzenes
(from 0.3 to 3.8%).
Additional data on quintozene residues (including metabolites and
impurities) derived from supervised trials indicate that residue
levels largely conform to the temporary tolerance levels recommended
by the 1969 Joint Meeting, the exception being peanut kernels on which
the composite residues of parent compound, metabolites and impurities
following recommended use patterns are such as to require a limit of 2
ppm.
Results of studies carried out on the use of quintozene for the
control of fungal complexes of Botrytis and Selerotinia in lettuce
grown in glasshouses were evaluated. A yearly proplanting soil
treatment of 3 g a.i./m2 as registered in some countries was found in
extensive supervised trials to give rise to residues which only
occasionally exceed 3 ppm. This established use pattern is reflected
in published data on residues found in lettuce moving in commerce
indicating that up to 43% of samples of commercial lettuce may carry
quintozene residues, the frequency being considerably higher in the
winter season than during summer when lettuce is mainly grown in the
open air.
Market sample surveys in European countries further show that
residues of quintozene (including impurities and metabolites) may be
present in up to 50% of root vegetables (carrots and potatoes)
examined. The residues in potatoes result from deliberate soil
applications during the growth of the crop whereas residues in carrots
originate from growing the crop in soils previously treated for
another crop.
Further studies of the persistence of quintozene in soils were
presented to the Meeting. Half-life values of from 4.7 to 9.6 months
were found in three Californian soils, whereas an average of 14 months
was required to give 50% degradation under more temperate Scandinavian
conditions.
Results of experiments where quintozene was fed to rats, dogs and
cows have been published. These studies confirmed an apparent lack of
metabolism of hexachlorobenzene and pentachlorobenzene which were
stored in tissues in concentrations reflecting the level of these
impurities in the technical quintozene. Excretion with the milk was
noticeable in the case of HCB.
Analytical methods for the determination of quintozene and
individual impurities and metabolites based on GLC-technique and
suitable for regulatory purposes are now available.
RECOMMENDATIONS FOR TOLERANCES, TEMPORARY TOLERANCES OR PRACTICAL
RESIDUE LIMITS
Recognizing that the major problem resulting from the use of
quintozene is the presence of persistent and intractable residues of
impurities, especially hexachlorobenzene, in the technical product it
is recommended that every effort should be made to encourage
manufacturers to reduce the amount of these impurities to the minimum.
The temporary tolerances recommended in 1969 have been confirmed.
New data justifies revision of the tolerances for lettuce and peanuts
and the following recommendations are made.
Tolerance
Lettuce 3 ppm
Peanuts (kernels) 2 ppm
It should be noted that the limits for quintozene residues in all
commodities include not only quintozene but the following impurities
and metabolites:
hexachlorobenzene;
pentachloroaniline;
methyl pentachlorophenylsulfide
pentachlorobenzene.
FURTHER WORK OR INFORMATION
Required before 1975
1. Carcinogenicity studies in two species of animal.
2. Short-term studies to elucidate the difference in the teratogenic
activity in rats and mice.
3. Studies to explain the effects on the liver and bone marrow of
dogs.
4. Comparison in rats and mice of the absorption, distribution, and
excretion of quintozene, its metabolites and any contaminants present
in significant concentrations in the technical product.
5. Further studies on the toxicity of metabolites.
6. Studies to show the nature and levels of residues in meat, milk,
and eggs following the feeding of quintozene residues in animal feeds.
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