1968 EVALUATIONS OF SOME PESTICIDE RESIDUES IN FOOD
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
Committee on Pesticide Residues, which met in Geneva, 9-16 December,
FOOD AND AGRICULTURE ORGANIZATION OF THE UNITED NATIONS
WORLD HEALTH ORGANIZATION
This pesticide has been previously evaluated (FAO/WHO, 1965). However,
no recommendations for acceptable daily intake or tolerances were
made. Since that time additional studies have raised further problems
which are outlined below. However, no further data have become
available on ethylene oxide toxicity per se.
Further information is now available on some of the reaction products
resulting from ethylene oxide fumigation of foodstuffs. The number of
known reaction products has increased considerably since 1965
(Lindgren et al., 1968).
Of these reaction products the ethylene oxide-amino acid adducts are
reported to be non-toxic (Lehman, 1965). There is no toxicological
information on the reaction products with carbohydrates, vitamins etc.
Ethylene chlorohydrin has been shown to result from fumigation of
foods with ethylene oxide due to interaction with natural chlorides
present in the crop. In flour fumigated with ethylene oxide, a level
of 260 ppm ethylene chlorohydrin has been detected. Fumigation of
spices also produced ethylene chlorohydrin (Wesley et al., 1965). A
consideration of the available toxicological data on ethylene
chlorohydrin is therefore pertinent to the assessment of ethylene
oxide (Anon., 1966a).
EVALUATION FOR ACCEPTABLE DAILY INTAKE
Biochemical studies (on ethylene chlorohydrin)
In the rat, orally-administered ethylene chlorohydrin rapidly depletes
liver glutathione and forms S-carboxymethylglutathione.
S-carboxymethylglutathione is degraded by kidney homogenates to
glycine, glutamic acid and S-carboxymethyl-cysteine. In the formation
of the S-carboxymethylglutathione, the intermediate metabolites
probably include chloroacetaldehyde, which is thought to be
responsible for the toxic properties of ethylene chlorohydrin
The formation of chloroacetic acid has been demonstrated in vivo.
Oxidation of ethylene chlorohydrin is unaffected by the presence of
the chlorine atom (Williams, 1959). A glucuronide is not formed in
rabbits (el Masri and Williams, 1956).
Acute toxicity (of ethylene chlorohydrin)
Animal Route LD50 mg/kg Reference
Rat (M) Oral 95 Smyth et al., 1941
Acute toxicity (cont'd)
Animal Route LD50 mg/kg Reference
Rat Oral 72 Goldblatt and
Rat i.p. 56 Goldblatt and
Guinea-pig Oral 110 Smyth et al.,
Short-term studies (on ethylene chlorohydrin)
In a 220-day feeding experiment incorporating 0, 100, 200, 400, 800,
1200, 1600, 2400, 3200, 6400 or 12 800 ppm of ethylene chlorohydrin in
the diet of 11 groups each containing five male rats, mortality
increased at and above the 6000 ppm level. At the 3200, 6400 and
12 800 ppm levels, 100 per cent mortality occurred in 49, 16 and seven
days respectively. Food intake was reduced at 1600 ppm and above and
the body weight gain was reduced at the 1200 ppm level and above. The
tissues of the rats at all levels showed no histological changes
Rodent diet containing up to 750 ppm of ethylene chlorohydrin
following ethylene oxide fumigation, has been suggested as a cause of
definite reduction in growth (Anon., 1966). Ninety-day feeding studies
in the rat and dog permit an estimate of 45 mg/kg as the no-effect
level for ethylene chlorohydrin. Results in monkeys were stated to be
"somewhat less clear cut but consistent with the no-effect level
determined for rats and dogs" (Anon., 1968a).
Long-term studies (on ethylene chlorohydrin)
Four groups of six female rats ingested 0, 4, 8 or 16 mg/kg of
ethylene chlorohydrin daily in their drinking water for two years. No
dose or compound related effects were noted on the mortality while the
histopathological examination of all the animals revealed no unusual
features (Johnson, 1967b).
The main identified reaction product of ethylene oxide left as a
residue on food is ethylene chlorohydrin. Some data on the probable
biochemical reactions of this substance are available, but none on the
rate of disappearance or on the amounts excreted following ingestion.
Data on acute toxicity, some short-term tests and one long-term study
on ethylene chlorohydrin have been reported. These data are
insufficient to permit an estimation of an acceptable daily intake for
either ethylene oxide or ethylene chlorohydrin or any other possible
reaction products remaining as residues.
RESIDUES IN FOOD AND THEIR EVALUATION
Residues resulting from supervised trials
Heuser and Scudamore (1968) experimentally treated flour at 25°C with
375 g ethylene oxide per 28.31 m3 and found from 13 to 23 ppm
ethylene chlorohydrin, depending on the moisture content of the flour.
At 570 g per m3 residues ranged from 33 to 57 ppm. A clear
relationship between concentration-time product and resulting ethylene
chlorohydrin residue level was established; there were no significant
differences between untreated and chlorine-dioxide-treated flour (the
latter with and without bromate). Pfeilsticker and Rasmussen (1967)
have shown that, depending on the moisture content, 20-50 per cent of
the ethylene oxide is decomposed in the course of wheat fumigation.
The outer membranes of the grain take up more ethylene oxide than the
endosperm, as is to be expected. These results were confirmed in a
later paper using fully labelled 14-C ethylene oxide (1968).
Evidence of residues in food moving in commerce
The Netherlands Government has consolidated residue information for
the period 1964-1966 for shipments of imported cereal produce (Anon.,
1968b) using an indicator tube method with a limit of detectability
for ethylene oxide of 0.1 ppm. Only two of 374 samples examined
(including 280 cereal samples) from world-wide sources showed
detectable residues: these were a consignment of rice from North Korea
(30 ppm) and one of peas from Leningrad (50 ppm).
Wesley et al. (1965) have shown that ethylene oxide will combine with
chlorine (derived from the small amounts of inorganic chloride present
naturally in the produce) to form ethylene chlorohydrin in various
products under fumigating conditions. Commercially fumigated ground
rice mixtures were found to contain 490 - 1030 ppm ethylene
chlorohydrin (average of 34 samples, 805 ppm) and little of this was
lost in autoclaving at 246°F for 70 min in subsequent soup production.
Other results for commercial fumigation for five hours at 750 ml
ethylene oxide per m3 were:
ppm ethylene chloroydrin
Desiccated coconut 42
Albumen (spray-dried) 310
French beans (deep frozen) 8
Green peas (air dried) 1
Green peas (ground) 36
These observations were generally substantiated by Ragelis et al.
(1966) for flour and pepper using gas chromatography supported by
infra-red and nuclear magnetic resonance spectroscopy: commercially
treated ground pepper contained 110 ppm. The following ethylene
chlorohydrin residues were found by Ragelis et al. (1968) in fumigated
foods in a later paper:
ppm ethylene chlorohydrin
Celery seed 83
Gum tragacanth less than 5
Heuser and Scudamore (1968) found 5 to 60 ppm ethylene chlorohydrin in
flour treated commercially at the rate of 2820 g ethylene oxide per
m3 plus 200 g ethylene oxide per metric ton of flour.
Hall (1968) has reported collaborative tests on fumigated spices by
six commercial firms. Of 37 products fumigated, 15 were found to
contain residues of ethylene chlorohydrin. Levels averaged more than
1000 ppm, ranging from 2760 ppm (cloves) to less than 23 ppm (mustard
flour), black pepper (1550 ppm) being regarded as the most significant
potential dietary source.
Fate of residues
As indicated above, free ethylene oxide can combine with chlorine in
foods (present as naturally occurring inorganic chloride) to give
residues of ethylene chlorohydrin (2-chloroethanol). This is contrary
to the conclusions of earlier workers, e.g. el Khishen (1950). At high
sterilization dose rates, ethylene oxide also reacts with moisture to
form ethylene glycol and, in the presence of sugars, glycol
derivatives (Vojnovich et al., 1967).
Evidence of residues in food in commerce or at consumption
No information available.
Methods of residue analysis
Various gas chromatographic systems have been described in the
literature for the separation, detection and measurement of residues
of ethylene oxide, ethylene chlorohydrin, ethylene glycol and
diethylene glycol in extracts of treated produce. The methods of
Wesley et al. (1965) and Ragelis et al. (1966) have been mentioned
above. Ben-Yehoshua and Krinsky (1968) describe a system suitable for
dates and a more recent and comprehensive system has been described by
Ragelis et al. (1968) for ethylene chlorohydrin in treated pepper,
celery seed, turmeric and gum tragacanth (together with propylene
chlorohydrin, 1-chloro-2-propanol, residues derived from the use of
propylene oxide on cocoa, walnut meats, tapioca starch, flour, glazed
cherries and glazed citron). Pagington (1968) has described a simple
gas chromatographic method for the determination of ethylene
chlorohydrin residues. Adler (1965) obtained a sensitivity of 0.1 ppm
ethylene oxide using a thermal conductivity detector: he also
describes a chromatropic acid method for total ethylene oxide plus
ethylene glycol (lower limit of sensitivity about 2 ppm) in sterilized
Heuser and Scudamore (1967, 1968) discuss the problem of extracting
ethylene chlorohydrin and of avoiding breakdown of ethylene oxide to
ethylene chlorohydrin in extraction procedures during analysis and
describe an improved method of extraction using aqueous acetone and
giving 98 per cent recovery of ethylene chlorohydrin. A gas
chromatographic method using a flame-ionization detector sensitive to
as little as 1 ng of ethylene chlorohydrin is also described.
Country Crop Tolerance (ppm)
United States of Spices, whole
America Walnut meats 50
Note: The British Industrial Biological Research Association has
suggested a limit of 300 ppm ethylene oxide in spices (Anon., 1966a,
1966b). There are no tolerances for ethylene chlorohydrin.
RECOMMENDATIONS FOR TOLERANCES AND PRACTICAL RESIDUE LIMITS
There is evidence that food treated with ethylene oxide, either as a
bacterial sterilent or to a lesser extent as an insecticidal fumigant,
may contain residues of unchanged ethylene oxide unless there is an
adequate subsequent holding period or aeration treatment to allow this
residue to volatilize. There is also evidence of the formation,
derived from inorganic chloride present naturally in food, of residues
of ethylene chlorohydrin; and limited evidence that this does not
disappear from the treated produce in storage so readily as do
residues of unchanged ethylene oxide.
In a general review of residues from post-harvest treatments, Lindgren
et al. (1958) summarize the earlier work of Oser and Hall (1956),
Bakerman et al. (1956) and Mickelsen (1957) on the vitamin losses in
ethylene oxide treatment.
In the absence of an acceptable daily intake no recommendations can be
made at this time.
Further work or information
Required (before acceptable daily intakes or tolerances can be
1. Additional data on the required rates and frequencies of
application, pre-harvest intervals, and the resultant residues.
2. Data on the disappearance of residues during storage and processing
following bactericidal or insecticidal treatment.
3. Data on the disappearance of residues resulting from commercial
4. Identification of reaction products with food, evaluation of the
effects on nutritional value, and toxicological studies on the
5. Determination of levels of ethylene chlorohydrin in fumigated
6. Long-term studies on ethylene chlorohydrin in experimental animals.
Data on the rate of disappearance of ethylene chlorohydrin or on the
Adler, N. (1965) Residual ethylene oxide and ethylene glycol in
ethylene oxide sterilized pharmaceuticals. J. Pharm. Sci., 54:
Ambrose, A. M. (1950) Toxicological studies of compounds investigated
for use as inhibitors of biological processes. II - Toxicity of
ethylene chlorohydrin. J. Industr. Hyg. occup. Med., 2: 591-597
Anon. (1966a) Possible hazards from ethylene oxide and propylene oxide
sterilization. Food cosmet. Toxicol., 4: 607-609. (Brit. industr.
biol. Res. Assoc., Info. Bull., 5 (4): 223-225)
Anon. (1966b) Proposed acceptable residue level of ethylene
chlorohydrin in spices. Brit. industr. biol. Res. Assoc., Info. Bull.,
5 (10): 644-645
Anon. (1968a) Safety of ethylene oxide spice fumigation reported.
Food Chemical News, 10 (26): 19-20
Anon. (1968b) Residues of insecticides in cereals and related products
imported into the Netherlands. Codex Alimentarius Commission document
Bakerman, H., Romine, M., Schricker, J. A., Takahashi, S. M, and
Mickelson, O. (1956) Stability of certain B vitamins exposed to
ethylene oxide in the presence of choline chloride. J. Agric. Food
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