AGP:1970/M/12/1
WHO/FOOD ADD/71.42
1970 EVALUATIONS OF SOME PESTICIDE RESIDUES IN FOOD
THE MONOGRAPHS
Issued jointly by FAO and WHO
The content of this document is the result of the deliberations of the
Joint Meeting of the FAO Working Party of Experts and the WHO Expert
Group on Pesticide Residues, which met in Rome, 9-16 November, 1970.
FOOD AND AGRICULTURE ORGANIZATION OF THE UNITED NATIONS
WORLD HEALTH ORGANIZATION
Rome, 1971
MANCOZEB
Explanation
Mancozeb was considered by the 1967 Joint Meeting. Since that time,
additional information on metabolism and methods of analysis has
become available and, along with some pertinent older data, is
summarized in this monograph addendum. Because much of this new
information is related to the comparative metabolism of mancozeb in
animals and plants, mancozeb has been considered separately from the
other dithiocarbamates. However, there is a chemical similarity of
mancozeb to many of the other dithiocarbamates, particularly maneb,
and biochemical and toxicological information on those compounds
should be borne in mind. Therefore, this monograph should be read in
conjunction with the monograph on dithiocarbamates other than
mancozeb.
EVALUATION FOR ACCEPTABLE DAILY INTAKE
BIOCHEMICAL ASPECTS
Six rats received a dose of 20 mg of mancozeb labelled with 14C in
the ethylene group for seven days (equivalent to approximately 100
mg/kg body-weight/day or 1000 ppm in the diet). After sacrifice on the
eighth day, the following metabolites were detected as percentage
radioactivity recovered: unchanged mancozeb, urine 0, faeces 47;
ethylene bis-isothiocyanate sulfide, urine 5.6, faeces 7.5; ethylene
thiourea, urine 28, faeces 6; ethylene urea, urine 12, faeces 2;
N-acetylethylenediamine, urine 19, faeces 0; N-formylethylene-diamine,
urine 1, faeces 0; ethylenediamine, urine 3.59 faeces 0. Information
indicating a similar metabolic fate in cows and in plants is given in
the section on "Fate of residues" (Lyman, 1970).
Further information on the metabolism of a number of dithiocarbamates
in rats is reported to be in progress in the Netherlands (Verschuuren,
1970).
High dose levels of mancozeb are reported to inhibit the activity of
redox enzymes containing sulfhydryl groups (Ivanova-Chemishanka,
1969).
TOXICOLOGICAL STUDIES
Special studies on reproduction
Rat
A three generation rat reproduction study at dietary levels of O, 25,
100 or 1000 ppm previously reported (FAO/WHO, 1968) indicated that
except for reduced fertility and variations in thyroid weight at the
1000 ppm level in the first and second filial generation, there was no
effect on reproduction. In particular, there was no report which would
indicate an embryotoxic or teratogenic effect (Larson, 1965a).
In the short-term study described below, where male and female rats
were fed one tenth or one fifth of the LD50, respectively, twice
weekly for four months (equivalent to 400 or 700 mg/kg body-weight per
day), there were five deliveries; some of the young were stillborn
and/or showed structural malformations (Ivanova-Chemishanka, 1969).
Rabbit
A study on rabbits employing the Somers test is reported to have
revealed no teratogenic effects at 25 and 250 mg/kg body-weight, but
details were not available (Swisher, 1970).
Special studies on carcinogenicity
In the study with groups of 18 mice of two hybrid strains (see the
monograph on dithiocarbamate fungicides apart from mancozeb),mancozeb
per se was not included. However, when the metabolite ethylene
thiourea was administered at 215 mg/kg body-weight per day from day 7
of birth until weaning and then incorporated into the diet at 646 ppm
until the mice were aged 18 months, the incidence of tumours was 14
out of 16 for the males and 18 out of 18 for the females in one strain
and 18 out of 18 and 12 out of 16, respectively, for the males and
females in the other strain (Innes et al., 1969).
Special studies on affect upon thyroid function
Groups of 15 male and 15 female rats were fed dietary levels of 0,
100, 300 and 1000 ppm of mancozeb for three months. Positive control
groups of rats were fed propylthiouracil at 300 ppm for three months
or 1333 ppm for five weeks. Oxygen consumption studies were conducted
during the third month, and at the end of the study 131I uptake was
determined for each animal, following which the thyroid gland was
examined microscopically. At 1000 ppm, terminal body weights were
adversely affected, and protein-bound iodine (PBI) was depressed in
the females; thyroid to body-weight ratios were elevated and the
metabolic rate was lowered in the males; one animal of each sex showed
significant thyroid hyperplasia; 131I uptake was not affected. At 100
and 300 ppm, PBI was significantly increased in both sexes, but
thyroid weights and histology and metabolic rates were unaffected. In
the groups fed propylthiouracil, weight-gain depression, increased
thyroid weight ratios, lowered 131I up-takes, lowered metabolic rates
and severe thyroid hyperplasia were seen in both sexes.
Propylthiouracil did not affect PBI (Larson, 1965b).
Non-dose related variations in thyroid to body-weight ratios in 8 of
20 rats fed 100 or 1000 ppm of mancozeb in the diet have been reported
(Larson, 1965a). In rats fed levels up to 1000 ppm of mancozeb for 90
weeks, there was hyperplasia of the thyroid acinar epithelium in the
group fed 1000 ppm but not at 100 ppm or lower levels (Larson, 1965c).
High dose levels of mancozeb administered to rats (equivalent to 400
or 700 mg/kg body-weight per day) resulted in thyroid hypertrophy and
reduced absorption of 131I (Ivanova-Chemishanka, 1969). In dogs fed
levels up to 1000 ppm of mancozeb for up to two years, the only
deviations from the controls in thyroid function were seen at 24
months in lower 131I uptake, at 48 and 72 hours in the group fed 100
ppm and at 72 hours in the group fed 1000 ppm (Larson,1965d).
Acute toxicity
The following additional information is available:
LD50 mg/kg
Animal Route body-weight Reference
Rat (M) oral 14 000 Ivanova-
Chemishanka,1969
Rat (F) oral 12 800 Ivanova-
Chemishanka,1969
Short-term studies
Rat
Groups of 24 male and 20 female rats were fed one tenth or one fifth
respectively of the LD50, in twice weekly doses for four months.
(This level is equivalent to 400 or 700 mg/kg body-weight per day or
8000 and 14,000 ppm in the diet.) Mortality was up to 50 percent in
the males and 35 percent in the females. After four months, signs of
paralysis were evident. There was also tracheitis and interstitial
pneumonia followed by a general toxic reaction affecting primarily the
liver and the kidneys less (Ivanova-Chemishanka, 1969).
Long-term studies
Rat
Studies are reported to be underway in the Netherlands with rats.
Preliminary results indicated that certain dithiocarbamate fungicides
may affect the reticuloendothelial and haematopoletic systems as
evidenced by the occurrence of slight anaemia, as well as effects on
the thymus, mesenteric lymph nodes and thyroid function. Details are
not yet available (Verschuuren, 1970).
OBSERVATIONS IN MAN
In a study on plant workers engaged in the manufacture of mancozeb, 54
employees exposed to varying levels of the fungicide were examined.
Tests included physical examinations, haematology (including
protein-bound iodine) and urinalysis. No abnormalities which could be
related to mancozeb were encountered, except for incidences of
dermatitis which were occasionally observed in a few sensitive
subjects (Megowan, 1965).
COMMENTS
Since mancozeb was last considered, some further information has been
forthcoming on the metabolism in certain plants. The indication from
those studies is that the metabolites are the same as those found in
animals. In particular, the content of ethylene thiourea in the
residues was similar. A considerable amount of work on a number of
dithiocarbamates is now in progress in the Netherlands. This work
involves short-and long-term studies and studies on mechanisms of
action and metabolism. Preliminary information from this work
indicated the existence of some effects on the reticuloendothelial and
haematopoietic systems as evidenced by slight anaemia, as well as
changes in the thymus, mesenteric lymph nodes and thyroid function in
rats. Work reported from eastern Europe also indicates that certain
dithiocarbamate fungicides affect reproductive physiology, may have a
carcinogenic potential and disturb the thyroid function. These
studies, particularly those involving maneb and zineb (see the
monograph on dithiocarbamates), may or may not be relevant in
assessing the toxicity of mancozeb. However, in the three generation
rat reproduction study with mancozeb previously reported (FAO/WHO,
1968), there was reduced fertility at 1000 ppm, but no indication of
embryotoxic or teratogenic effects.
For the above-mentioned reasons, it was considered that the temporary
acceptable daily intake should remain at the same figure as previously
established, but because some information is now available comparing
the similarity of metabolites in plants and animals, the temporary
acceptable daily intake for mancozeb need no longer be considered to
be applicable to the parent compound only.
TOXICOLOGICAL EVALUATION
Level causing no toxicological effects
Rat: 100 ppm in the diet, equivalent to 5 mg/kg body-weight/day
ESTIMATE OF TEMPORARY ACCEPTABLE DAILY INTAKE FOR MAN
0-0.025 mg/kg body-weight
RESIDUES IN FOOD AND THEIR EVALUATION
Identity of residues
As recorded in the report of the 1967 meeting, the following metabolic
intermediates from both plant and animals have been identified:
ethylene bis-isothiocynate sulfide (EBIS), ethylene thiourea (ETU),
ethylene diamine (EDA), ethylene urea (EU), N-formyl ethylenediamine
and N-acetyl ethylenediamine (from rats). EBIS is the proposed new
structure for ethylenethiuran monosulfide (EMS) - formerly suggested
as an alternate (Thorn, 1960) and subsequently substantiated (Rohm and
Base, 1970).
From experiments with the application of mancozeb to potato, radish
and tomato plants, metabolism to ethylenediamine was followed by
oxidation to glycine and ultimate incorporation of fragments into the
metabolic pool.
RESIDUES FOLLOWING USE IN THE FIELD
Analytical methods
In view of the modified carbonbisulfide liberation method (Gordonet
al., 1967) not being specific for dithiocarbamates and neglecting
metabolites such as ETU and EDA, a method has been developed (Rohm and
Haas, 1970) for the determination of EDA, which is liberated from
known components of residues (mancozeb, EDA, EU, ETU, EBIS and
N-acetyl ethylenediamine). The sensitivity of detection for the method
is 0.01 ppm (as EDA) or 0.05 ppm (as mancozeb). Because of the
importance of knowing the magnitude of the ETU component in the
residue, a separate method was developed (Rohm and Haas, 1970) that is
sensitive to 0.01 ppm for milk and cow tissues and originally 0.05 ppm
for potatoes.
Analysis of field-treated potatoes for mancozeb residues
All residue results included in this summary were determined by the
ethylene thiourea (ETU) method and calculated as ETU (sensitivity,
0.05 ppm). Most of the same samples were analyzed for mancozeb
residues determined as ethylene diamine (sensitivity, 0.05 ppm as
mancozeb) (See Table I).
NDR signified "no detectable residue" at the sensitivity of the
residue method.
Over 306 samples were collected in 1969 from eleven different states.
Treatments ranged from 1 to 3 lb/acre with total quantities ranging
from 8 to 36 lb/acre, depending on number of treatments. Among the 40
different sets of samples collected, in two sets no residue was
detected (<0.05 ppm). In a group having the highest treatment rate
(36 lb/acre total) with an eight day harvest interval, the results
ranged from non-detectable to 0.60 ppm, with an average of 0.17 ppm.
The highest level found was 0.78 ppm with a grand average of 0.17 ppm.
No ETU was detected, as noted at the sensitivity level of 0.05 ppm.
This checks with a 14C tracer experiment where a level of 0.0022 ppm
was found using the reverse isotope dilution technique.
Although traces of residues were found for some unexplainable reason
in the control samples, the ingestion of mancozeb residues as might
occur on leafy crops will not lead to residues in milk until the level
exceeds 10 ppm.
TABLE I
Mancozeb residues in field treated potatoes
Sample Treatment rate Number Final
Source Lb/Acre of Treatment Residues, ppm
Total Lb for Treatments Harvest
Season Interval ETU Mancozeb
Days Max Max
ALABAMA
Grove Oak
70-88 2/4 2 0 NDR -
CALIFORNIA
Shafter
69-79 2/12 6 55 NDR 0.19
Arvin
70-76 2/2 1 0 NDR -
FLORIDA
Sanford
2-69-32 1.5/10.5 7 0 NDR 0.21
Sanford
2-69-266 2/22 11 0 NDR 0.28
IDAHO
Penghoe 2,3,2.5/18.5 6 17 NDR 0.19
69-50
Blackfoot
69-50 2,3/11 5 12 NDR 0.63
Blackfoot 0.78
69-50 2.5/20 8 0 NDR Highest Value
Nowya
69-52 2/12 6 14 NDR 0.48
INDIANA
Rensselear
69-55 1,1.5,2/12 8 31 NDR 0.55
NEW JERSEY
C. Bullock
Allentown
2-69-194 2/8 4 46 NDR NDR
2/8 4 46 NDR NDR
TABLE I (cont'd)
Mancozeb residues in field treated potatoes
Sample Treatment rate Number Final
Source Lb/Acre of Treatment Residues, ppm
Total Lb for Treatments Harvest
Season Interval ETU Mancozeb
Days Max Max
John Field
Allentown
2-69-194 2/10 5 34 NDR NDR
Imlaystown
2-69-194 2/12 6 39 NDR 0.44
NEW YORK
Prattsburgh
2-69-192 3/36 12 8 NDR 0.60
OHIO
Columbienia
2-69-206 2/16 8 14 NDR 0.12
Lisbon
2-69-206 2,2.5,3/22.5 9 8 NDR 0.12
PENNSYLVANIA
Orefield
68-105 2/12 6 2 NDR 0.35
2/18 9 4 NDR 0.50
2/6 3 4 NDR 0.35
WISCONSIN
Antigo
68-109 1.5,2/21 12 7 NDR 0.40
Eagle River
68-109 2/24 12 7 NDR 0.38
MAINE
Washburn
2-69-202 1,1.5/12.5 12 6 NDR 0.16
2-69-203 1,1.5/16 12 2 NDR 0.15
Garibou
2-69-204 1.5/19.5 13 0 NDR 0.15
TABLE I (cont'd)
Mancozeb residues in field treated potatoes
Sample Treatment rate Number Final
Source Lb/Acre of Treatment Residues, ppm
Total Lb for Treatments Harvest
Season Interval ETU Mancozeb
Days Max Max
MICHIGAN
Greenville
69-55 2/8 4 20 NDR 0.35
Samara
69-55 1.5/10.5 7 15 NDR 0.33
Analyses of milk for mancozeb residues1
Feed Level (ppm Mancozeb)
Control 0.78 9.72 38.9 97.2
No. of samples 35 45 35 35 35
No. of values >0.05 ppm2/ 4 0 15 28 33
Highest value ppm 0.10 - 0.08 0.29 0.71
Av. of residues found ppm 0.06 - 0.06 0.11 0.32
1/ calculated as mancozeb from EDA method
2/ sensitivity of method
Analyses of milk for ETU
Feed Level (ppm Mancozeb)
Control 9.72 38.9 97.2
No. of samples 24 28 23 28
No. of values >0.01 ppm1/ 2 5 11 26
Highest value found ppm 0.01 0.01 0.02 0.23
Av. of residues found ppm 0.01 0.01 0.01 0.05
1/ sensitivity of method
Residues in soil
Radioassay of 14C-labelled mancozeb in soil where two varieties of
potatoes were grown showed a drop in activity, calculated as ppm of
mancozeb, from 0.72 to 0.16 and 1.88 to 0.33 in the interval Oct. 7/69
to March 17/70.
RECOMMENDATIONS FOR TOLERANCE
TEMPORARY TOLERANCE
With the demonstration of the similarity of metabolites in plants and
animals, their quantitative measurement and the absence of detection
of ethylenethiourea in extensive field testing of potatoes, it is
possible to recommend a temporary tolerance of 1 ppm.
FURTHER WORK OR INFORMATION
REQUIRED (by June 1973)
1. Elucidation of the effect on the reticuloendothelial and
haematopoietic systems.
2. Further clarification of the possible carcinogenic effect of these
compounds.
3. Elucidation of the effect on thyroid function.
REQUIRED (Before further tolerances can be recommended)
Further studies on the biotransformation of the compound in plants to
determine the chemical nature of the residues, followed by appropriate
toxicological studies. The extensive residue data already submitted
need to be validated by the diethylamine method and by measuring the
level of ethylene thiourea. (Note: Some of these data are known to be
available but were not submitted in time for detailed scrutiny by the
Meeting.)
REFERENCES
FAO/WHO (1968) 1967 Evaluation of some pesticide residues in food.
FAO/PL: 1967/M/11/1; WHO/Food Add./68.30
Gordon, C.P., Schukert, R.J. and Bornak, W.E. (1967) Improved method
for the determination of ethylene bis-dithiocarbamate residues in
plants, fruits and vegetables.
Innes, J.R.M., Ulland, B.M., Valerio, M.G., Petrucelli, L. Hart,
E.R., Pallotta, A.J., Bates, R.R., Falk, H.C., Gart, J.J., Klein, M.,
Mitchell, I. and Peter, J. (1969) Bioassay of pesticides and
industrial chemicals for tumorigenicity in mice: a preliminary note.
J. nat. Cancer Inst., 42: 1101-1114
Ivanova-Chemishanka, L. (1969) Toxicologic characteristics of
mancozeb (in Bùlgarian).Higiena i Zdraveopazvane, 12: 418-426
Larson, P.S. (1965a) Three generation reproduction study on rats
receiving Dithane M-45 in their diet. Unpublished report from the
Department of Pharmacology, Medical College of Virginia, submitted to
Rohm and Haas Co.
Larson, P.S. (1965b) Correlative study of functional and morphologic
changes in the thyroid glands of rats receiving Dithane M-45 or
propylthiouracil in their diet. Unpublished report from the Department
of Pharmacology, Medical College of Virginia, submitted to Rohm and
Haas Co.
Larson, P.S. (1965c) Toxicological study on the effect of adding
Dithane M-45 to the diet of rats for a period of 90 weeks. Unpublished
report from the Department of Pharmacology, Medical College of
Virginia, submitted to Rohm and Haas Co.
Larson, P.S. (1965d) Toxicologic study on the effect of adding Dithane
M-45 to the diet of beagle dogs for a period of two years. Unpublished
report from the Department of Pharmacology, Medical College of
Virginia, submitted to Rohm and Haas Co.
Lyman, W.R. Dithane M-45. (1970) Chemistry and metabolism of terminal
residues. Unpublished report, submitted to FAO and WHO by Rohm and
Haas Co.
Megowan, R. (1965) Dithane health study. Unpublished report from
Bridesburg Medical Department, submitted to Rohm and Haas Co.
Rohm and Haas Unpublished data, submitted to FAO 1967 and 1970
Swisher, E. (1970) Unpublished information on work conducted at the
University of Toronto, provided by Rohm and Haas Co.
Thorn, G.D. (1960) Some observations on the structure of
ethylenethiuram monosulphide. Can. J. Chem., 38: 2349-2358
Verschuuren, H.G. (1970) Information provided verbally to the 1970
Joint FAO/WHO Meeting on Pesticide Residues on work being conducted on
dithiocarbamate fungicides in The Netherlands.
See Also:
Toxicological Abbreviations
Mancozeb (ICSC)
Mancozeb (FAO/PL:1967/M/11/1)
Mancozeb (WHO Pesticide Residues Series 4)
Mancozeb (Pesticide residues in food: 1993 evaluations Part II Toxicology)