BROMOPHOS JMPR 1975
Explanation
When reviewing the recommendations of the 1972 JMPR, the Codex
Committee on Pesticide Residues at its 8th Session (CCPR, 1975) asked
for information on residues of the bromophos metabolite
2,5-dichloro-4-bromophenol, which is also a metabolite of
bromophos-ethyl and other compounds, and whether this metabolite
should be included in the proposed tolerances (para. 34, CCPR, 1975).
The Joint Meeting was also asked:
(1) to reconsider the residue data reported in the 1972 Monograph
and to indicate the pre-harvest intervals, rates of application,
etc., on which the recommendations were based (para. 35);
(2) to recommend maximum residue limits for peanuts and tropical
grains (para. 35), and to reconsider the limit for red currants
(para. 36);
(3) to consider the possible occurrence of residues in milk and
meat of cattle arising from bromophos residues up to 2 mg/kg in
sugar beet leaves and 0.5 mg/kg in sugar beet roots (para. 38);
(4) to establish limits for residues in milk products in addition
to the existing limits for milk, and for Brussels sprouts and
broad beans (para. 40).
Some information on residues of bromophos in Brussels sprouts
(pre-harvest treatment) had been supplied to the Meeting and was
considered. New data relating to usage on stored grain and to the fate
of residues on storage and processing, that had been included amongst
the requirements listed in the monograph of the 1972 meeting were also
reviewed.
RESIDUES RESULTING FROM SUPERVISED TRIALS
Pre-harvest treatment
Residue data in Brussels sprouts for the raw agricultural
commodity (RIV, 1967) and after cleaning, washing and cooking (RIV,
1974) have become available from the Netherlands. Details are given in
Table 1.
TABLE 1. Bromophos residues in Brussels sprouts
Residue mg/kg after interval (days)
Application
No. Rate (kg/ha) 7 14 21
2-3 0.6-0.7 0.01 0.01
1 0.7 0.2-0.3a 0.1-0.2a
1 0.7 0.04-0.07b <0.04b
1 0.7 <0.04c <0.04c
a Ready for marketing.
b After cleaning and washing.
c After cleaning, washing and cooking.
Post-harvest treatment
In a test reported from South Africa, maize and sorghum were
sprayed with bromophos at different concentrations (EC) on a conveyer
belt or on the flowing grain stream (Dep. Agr. Techn. Serv., 1975).
The results are summarized in Table 2. It is noteworthy that the
percentage of germination of maize at the beginning of the trials was
99%, 50 weeks after treatment it was still 97% in grain treated with 5
and 10 mg bromophos/kg, but only 41% in untreated maize (control).
In another study reported by Eichler and Knoll (1975), 100 kg
lots of 15% and 13.5% moisture and as commonly used for being were
treated experimentally with bromophos at 8 and at 12 mg/kg. The
insecticide was applied as a dust (12%) and as an emulsion concentrate
(40%) at each dosage level. These lots were then stored in open
containers in a room at ambient temperature ranging from 9 to 22°C.
Untreated lots were also stored under similar conditions for
comparative purposes. Samples of grain were taken from each lot after
3, 6 and 12 months storage.
TABLE 2. Residues of bromophos (mg/kg) in stored maize and sorghum (Selection of data from original report)
Storage after application (months)
0 1 3 6 10 12
(a) 10 8.7 8.2 6.6 2.3 -
(a) 5 - 4.2 1.6 0.7 -
(b) 5 3.5-4.3 2.6-3.9 1.4-1.6 - -
(c) 7.5-8 5.1-6.2 3.3-4.9 3.1-5.5 - -
(d) 8 - - - - 1.4
(e) 8 7.8-8.0 5.7-6.1 1.3-2.0 - -
EXPLANATORY NOTES
Amount of Grain Moisture
Type of Storage (tons) Content Temperature Sampling Arrangements
(a) Vertical cylindrical 3 samples of 1 kg from surface
bins holding 725 metre 54.4 12% 12-30° in bins layer, 20 feet below and at
tons Maize bottom. All mixed
(b) 2 bins, as (a) 54.4 12% as (a) 3 samples of 1 kg from the
Maize upper surface. Mixed
TABLE 2. (continued)
EXPLANATORY NOTES
Amount of Grain Moisture
Type of Storage (tons) Content Temperature Sampling Arrangements
(c) Horizontal bulk containers Completely filled 12-12.6% 10-32° in bin 4 samples of 1 kg at 4 points at
holding 1750 metric tons with maize surface. Mixed
(d) Bags in room 11 m3 Several bags, maize 28° in room
(e) 2 bins 725 metric tons 54.4 12-30° in bins as (a)
each Sorghum
Samples were milled under simulated commercial conditions into
flour and subsequently made into bread. Others were crushed into a
wholemeal flour before baking. Analyses were undertaken on various
samples during the course of the test. These included analyses of raw
grain, flour, bran and bread. A GLC method, sensitive to about 0.01
mg/kg was used. Small amounts of 2,5-dichloro-4-bromophenol were found
in the wheat grains (see Table 3) but not more than traces of
bromoxone.
Losses on storage of raw grain
As indicated in Tables 4 and 5, between 37 and 50% of the
residues of bromophos disappeared over a 12 month period of storage.
Supplementary experiments indicated that the rate of degradation was
greater at higher storage temperatures, reaching about 60% at 26°C.
TABLE 3. Residues of 2,5-dichloro-4-bromophenol (ppm) in wheat grainsa,b
Application of Application of
8 ppm a.i. 12 ppm a.i.
Months
after
application Dust Emulsion Dust Emulsion
6 0.35 0.23 0.44 0.49
12 0.40 0.39 0.70 0.80
a Moisture content: 13.5%.
b Storage temperature: 15°C.
TABLE 4. Degradation of bromophos (ppm) in wheat grains;a comparison
of dust and emulsion
Application of Application of
8 ppm a.i. 12 ppm a.i.
Months
after
applicationb Dust Emulsion Dust Emulsion
0 6.8 5.4 10.4 9.4
3 4.3 5.6 7.2 9.2
6 4.3 3.5 6.7 6.2
12 4.1 3.4 6.1 4.7
Degradation
after 40% 37% 41% 50%
1 year
a Storage temperature at 15°C.
b Application in February.
TABLE 5. Degradation of bromophos (ppm) in wheat grainsa with varying
moisture content and under varying storage temperatures
Months
after m.c. 13.5% m.c. 13.5% m. c. 15%
applicationb temp. 15° temp. 26° temp. 26°
0 9.4 9.4 9.4
3 9.2 5.7 5.4
6 6.2 5.0 4.7
12 4.7 3.6 3.7
a Application of 12 ppm a.i. as emulsion.
b Application in February.
Distribution in milled products
As has been found with various other pesticides applied to stored
grain in dust or emulsion concentrate formulations, the bran fractions
were found to contain the highest residue and the white flour the
least. Similarly, white bread contained significantly lower residues
than bread from whole crushed wheat. This is illustrated in Tables 6
and 7, which indicate the levels that may occur in flour and bread
following treatment of wheat under commercial conditions. Based on the
above studies the meeting decided to recommend temporary maximum
residue levels for wheat, flour and bread.
TABLE 6. Comparison of bromophos residues (ppm) in flour and bread
Application Application
Months of dusta of emulsiona
after
application Flour Bread Flour Bread
3 2.34 0.18 2.66 0.30
6 1.02 0.12 0.99 0.10
12 1.17 0.08 1.10 0.07
a Application of 12 ppm a.i.
TABLE 7. Comparison of bromophos residues (ppm) in crushed grain and bread
Application Application
Months of dusta of emulsiona
after
application Crushed grain Bread Crushed grain Bread
3 7.2 1.59 9.2 2.48
6 6.7 1.73 6.2 2.05
12 6.1 2.23 4.7 1.40
a Application of 12 ppm a.i.
IDENTITY OF RESIDUES IN PLANTS
As already reported earlier (FAO/WHO, 1973) application of
bromophos to tomato plants resulted in residues of the parent compound
and 2,5-dichlor-4-bromophenol as a main metabolite. Detailed
information on this subject was published by Eichler (1972). Following
application of 1.1 mg of bromophos-3H to tomato plants, residues were
determined in the waxy layer of treated leaves, the leaves with the
waxy layer removed, and the remainder of the plant. The results are
listed in Table 8.
Manitoba wheat which had been treated with 10 mg bromophos/kg
contained 3-4 mg of the parent compound after five weeks and showed a
corresponding rise in levels of 2,5-dichloro-4-bromophenol.
Desmethylbromphos appeared also as a decomposition product, especially
three weeks after application, and not more than traces of bromoxon.
Detailed studies (Rehbinder, 1966) have shown that bromoxon is the
only metabolite of toxicological significance.
APPRAISAL
Data on rate of application, safety intervals and so on reported
in the 1972 Monograph (FAO/WHO, 1973) have been reviewed. The
pre-harvest interval was judged to be seven days for the majority of
fruit and vegetables, four days for cucumbers and tomatoes, 14 days
for forage, 21 days for radishes, 30 days for kohlrabi and 42 days for
cabbage, carrots and onions.
On the basis of residues found in Brussels sprouts and by analogy
with the temporary tolerance for peas (FAO/WHO, 1973) maximum residue
limits of 0.5 mg/kg are recommended for Brussels sprouts and of 0.1
mg/kg are for broad beans (without pods).
New information on residues in stored maize, sorghum and wheat,
and on residues in processing of wheat, received in response to the
requirement at the 1972 meeting was reviewed. This enabled
recommendations to be made for temporary maximum residue limits for
these grains and for certain wheat products.
No recommendations could be made for peanuts and for milk
products because relevant information had not become available.
The Meeting considered whether the bromophos metabolite
2,5-dichloro-4-bromophenol should be included in the proposed maximum
residue limits. This seems not necessary nor advisable because the
proportion of 2,5-dichloro-4-bromophenol in the residue is very small
compared with the bromophos. Furthermore, 2,5-dichloro-4-bromophenol
is also a degradation product of bromophos-ethyl, leptophos
O-(4 bromo-2,5-dichlo-phenol) O-ethylphenyl, phosphorothioate and
similar pesticides.
TABLE 8. Metabolites of bromophos-3H in tomato plantsa
Treated leaf
Remainder of plant
Waxy layer Interior leaf excluding root Whole plant
Amt. of Amt. of Amt. of Amt. of Percent. of
Bromophos and Extract substance Extract substance Extract substance substance bromophos
Day metabolites (%) (µg) (%) (µg) (%) (µg) (µg) dose applied
Bromophos 96 66.5 80 370 66 2.2 438.7 40
Bromoxon 0.1 0.0 0.4 1.8 1 0.03 1.83 0.1
1 Dichlorobromophenol 5 2.3 10 30.5 8 0.2 33.0 4.6
Total 101.1 - 90.4 - 75 - - 44.7
Bromophos 74 13.7 63 126 46 2.0 141.7 12.9
Bromoxon 0.4 0.07 0.5 1.0 7 0.3 1.37 0.2
2 Dichlorobromophenol 15 1.9 26 34.3 13 0.4 36.6 5
Total 90 - 90 - 66 - - 18.1
Bromophos 9 6.9 7 8.6 11 0.7 16.2 1.5
Bromoxon 0.4 0.3 0.4 0.5 1 0.06 0.86 0.1
7 Dichlorobromophenol 94 47.7 58 46.6 16 0.7 95.0 13.1
Total 103.4 - 65 - 28 - - 14.7
a In each case following application of 1.1 mg of bromophos-3H to one leaf of a plant.
RECOMMENDATIONS
The following additional maximum residue limits (see FAO/WHO,
1973) determined and expressed as bromophos are recommended.
MAXIMUM RESIDUE LIMITS
Bromphos
Commodity (mg/kg)
Bran (wheat) 20
Raw grain (wheat, maize, sorghum) 10
White flour, wholemeal bread 2
White bread 0.5
Brussels sprouts 0.5
Broad beans (without pods) 0.1
FURTHER WORK OR INFORMATION
REQUIRED (by 30 June 1977) (in addition to the information listed
in FAO/WHO, 1973a, p. 42 and before additional maximum residue limits
can be recommended)
1. Residue data on fat of meat of domestic animals other than
sheep, including residues in milk products, poultry, eggs
and on peanuts for which recommendations have not been made.
DESIRED (in addition to the information listed in FAO/WHO, 1973a, p.
42)
1. Further information on residues in stored wheat and on rice
following storage and processing under full-scale commercial
conditions.
REFERENCES
CCPR Codex Alimentarius Commission of the FAO/WHO. (1975) Report of
the 8th Session of the Codex Committee on Pesticide Residues. (CL
1975/13, August 1975)
Dep. Agr. Techn. Serv. Department of Agricultural Technical Services,
Pretoria, South Africa. (1975) Report on a trial of bromophos on
stored maize and sorghum ((25-9-1975) 39/4/9)
Eichler, D. (1972) Bromophos and bromophos-ethyl residues. Residue
Reviews, Vol. 41, 65-112. F. A. Gunther, Ed. (1972)
Eichler, D. and Knoll, H. A. (1975) Degradation of bromophos in stored
wheat. Proceedings of First International Working Conference of Stored
Products Entomology, Savannah, USA (7-11 Oct. 1974)
FAO/WHO. (1973) 1972 Evaluations of some pesticide residues in food.
WHO Pesticide Residue Series, Nu. 2 (Geneva, 1973)
Rehbinder, D. (1966) C. H. Boehringer Sohn, Ingelheim, unpublished
information (see Eichler, 1972)
RIV (1974) Rijksinstituut v.d. Volksgesondheid, No. 61/74 Tox-Rob
Residuen van bestrijdingsmiddelen in groenten an fruit in diverse
stadia vanshoudelijke bereiding (April 1974)
RIV Rijksinstituut v.d. Volksgesondheid, Unpublished report (U 124/67
Tox W/ad)
See Also:
Toxicological Abbreviations
Bromophos (WHO Pesticide Residues Series 2)
Bromophos (Pesticide residues in food: 1977 evaluations)
Bromophos (Pesticide residues in food: 1982 evaluations)
Bromophos (Pesticide residues in food: 1984 evaluations)