Poisonous Spray Residues on Vegetables W. B. WHITE U. S. Food and Drug Administration, Washington, D. C.
T
HIS discussion will be limited to spray residues carrying arRenic, fluorine, and lead. One might paraphrase the scriptures by adding “and the greatest of these is lead.” Lead and arsenic frequently occur together in vegetable spray residues as the well-known lead arsenate, although other arsenicals, such as magnesium and calcium arsenates, are not uncommon. The fluorine insecticides, cryolite and the fluosilicates, are newcomers in the field, and entomologists are cautious about making sweeping conclusions as to their effectiveness from the standpoint of pest control. Coming from this laboratory, it is natural that the whole subject of poisonous spray residues on vegetables should be discussed from the standpoint of the Food and Drug Adpinistration. The Food and Drugs Act was drawn to protect American consumers against harmful, revolting, debased, and misrepresented foods. We are concerned here with the harmful aspect. J‘egetables carrying amounts of poisonous spray residues which may render the food injurious to the health of any citizen are within the ban of the statute. It is thus our clear duty in the interest of public health to impound all interstate shipments of sprayed or dusted vegetables which are capable of causing the slightest measurable derangement in the health of any consumer. Economic disturbances resulting from such regulatory action must be subordinated to this aim. The spray residue problem is no new one, having grown in the last fourteen years until it is now absorbing about one-t!iird of the total appropriation of this bureau. ,4 total of 221 shipments of sprayed fruit and vegetables seized in the past 8 months, against only 103 in the previous year, furnishes eloquent proof of the growing acuteness of this question. Recent reckless use of insecticides on vegetable crops has cawed such concern on the part of federal entomologists that the Bureau of Entomology recently issued a circular, addressed to experiment stations and state entomologists, advising the utmost caution in making spraying and dusting recommendations for vegetable crops, with special emphasis on the avoidance of lead compounds wherever possible. Stress was also placed on the necessity for extreme caution in the use of arsenicals or fluorine compounds, and the substitution of less poisonous materials wherever adequate control could be secured by these substitutes. Several warnings of a more general nature had previously issued over the signature of every responsible federal official. RECKLESS USE
INSECTICIDES It seems incredible that a truck farmer would be so ignorant of the poisonous effects of lead arsenate that he would apply it, close to the harvesting period, by sifting it through a burlap sack or by peppering it on the plants through a large tin can with nail holes in the bottom. This practice, however, was distres,qingly frequent in certain sections of the country. Loose leaf cabbage has been seized and destroyed, for example, which carried nearly two hundred times the safe limit for arsenic and correspondingly high amounts of lead. Shipments of cauliflower have been seized which carried amounts of lead arsenate which would unquestionably produce, not chronic symptoms detectable with great difficulty after long continued administration, but immediate and acute poisoning of a serious nature. Up to the present the principal action has been against cauliflower, cabbage, and celery. OF
The following table represents the high spots of a single regulatory campaign extending over a period of 2 months or less on each vegetable: ClBBAGE Size of shipment
-40908
Grains/lb. 1.473 0.50 0.354 0.259 0.273
410 hampers 180 hampers 425 hampers 271 hampers 112 hampers CAULIFLOWER
Remarks
As203
Grains/lb. 2.059 1.602 0.516 0.342 0 369
Leaves only 1 entire head Leaves only A v . of entire lot Entire stalk including leaves CELERY
Remarks
As202
Grains/lb. 0,209
0.13
0.044 0.047 0.043
126 crates, 100 half-crates Leaves only 324 crates 342 crates Carload
Constant surveillance must be maintained in order to detect such sporadic outbreaks before they result in serious injury to the health of the consuming public. I n every case the interstate shipment was either destroyed or rendered safe for consumption by stripping or washing. Generally speaking, these three vegetables can, by washing or stripping operations, be rendered safe for consumption even when they carry rather heavy loads of poisonous req’d Li ue. Cabbage of the tight-headed variety can usually be made safe by removing the outer and looser leaves. It is different with the loose-headed varieties where sometimes nearly half the head must be stripped off to reduce the arsenic and lead to negligible amounts. Here, there is sometimes no remedy but destruction. Celery can be rendered qafe in some cases by Tyashing with water under pressure, unless flour or other “stickers” have been employed, when removal is only partial. The arsenicals have been found ineffective against celery leaf tier, the major pest on southern celery, because they do not penetrate to his sphere of operations. Spray residue on cauliflower, thanks to the cultural methods employed, is usually concentrated in the leaf axils, where stripping and trimming operations largely remove it. S a t u rally such stripping seriously affects the merchantability. Sprayed cauliflower 1% ould probably never have become a menace to health had there not been a growing practice of serving the leaves in homes and public eating places. With vegetables such as lettuce, broccoli, and the “greens,” where stripping or washing is utterly out of the question, the avoidance of lead, arsenic, and fluorine compounds, except when these will be completely removed by natural weathering, is necessary. Here, as in the case of sprayed fruits, state and municipal governmental agencies can do yeoman service by adequate policing and control methods which will protect the health of their own citizens and, a t the same time, guard the growers against damaging and demoralizing regulatory operations against interstate shipments. There is 8 prevailing misapprehension, especially in the minds of those whose interests are involved, that because they themeelves have never been seriously injured by
621
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INDUSTRIAL AND ENGINEERING CHEMISTRY
contact with spray materials or by eating sprayed vegetables, there is no danger to human health involved. What chiefly concerns regulatory officials is not immediate acute effects easily diagnosed and resulting in serious illness or death, but rather those more remote and insidious chronic effects which follow the frequent administration of small amounts of poison over a period of several years. Many rumors of death or serious illness from spray residues have been run down, but it is only in rare instances that the cause had been definitely traced to this source.
SAFEGUARDING PUBLICAGAIKST POISONOUS RESIDCES From the abstract public kealth standpoint, there can be no quarrel with the view that the safest course is the complete abandonment of poisonous sprays. However, since we are not operating under the Napoleonic code, the nature of American criminal law is such as to render it difficult to prove the potential danger to human health of traces of certain substances well known to be poisonous when present in relatively large amounts. The liberal Supreme Court opinion (9) in the celebrated bleached flour case goes far, in that it is required to prove only that the harmful ingredient must be present in such amounts as to have the possibility or probability of affecting the health, not only of those in the vigor of youth, but the young, the aged, and the sick. The present so-called world tolerance for arsenic of 0.01 grain of arsenious oxide per pound of food, dates back to 1900, when in England and Wales more than six thousand persons were made ill, and seventy of them killed by the consumption of beer containing traces of arsenic. The comprehensive report of the British Royal Commission, headed by Kelvin, remains a classic in this field ( I ) . Whether the recent work of Myers, Throne, and their co-workers (6) may set an even more drastic safe limit for arsenic and other spray poisons remains to be seen. We have prepared the following brief summary of a paper by Wright, Sappington, and Rantoul (I?2), based on the findings of the Industrial Clinic of the Massachusetts General Hospital. About 11 per cent of all cases of lead poisoning in the Industrial Clinic of the Massachusetts General Hospital, over the period of 1911-1923, were nonindustrial in origin. One hundred and two cases were from families consuming drinking water flowing through lead pipes. Of all persons exposed, about 25 per cent showed gross symptoms of lead-poisoning-namely, a blue line about the gums, stippled blood cells, and in many instances, pallor, weakness, and digestive disturbances. Fourteen persons ingesting as little as 0.1 milligram (about 1/700 grain) daily of lead over an average period of 81/4 years, exhibited these symptoms. It is pertinent here t o observe that one moderately sprayed apple might readily contain more than 0.1 milligram of lead unless subjected to appropriate cleansing treatment.
It is only recently that the pathological condition of human teeth, known to dentists as mottled enamel, was definitely traced to fluorine compounds in drinking water. The endemic nature of this disease had been known for some time, and it had been traced to the drinking water, but to Smith (7‘) goes the credit for picking the actual culprit. Her work has definitely established that 2 to 3 p. p. m. of fluorine in drinking water may cause trouble. These findings have led the Department of Agriculture to warn the industry against any statements or representations that fluorine insecticides may be used in place of lead arsenate and other arsenicals with any assurance that less caution will be required in their application and removal before placing vegetables in the channels of trade. The phrasing of the Federal Food and Drugs Act is such that foods must contain added poisonous ingredients to bring them under the ban against adulterated food. Kotwithstanding the limitations of the statute the Food and Drug
Vol. 25, No. 6
Administration has undertaken, in the interest of the consuming public, a nation-wide survey of the arsenical content of practically all classes of food, whether or not it could be established by adequate evidence in a criminal court that the arsenic was an added ingredient. A total of 1169 samples has been reported to date of which 129 samples, or 11 per cent, contained arsenious oxide in excess of 0.01 grain per pound, the so-called world tolerance. A large amount of work remains to be done, and, when this is completed, a similar survey will be made of the lead content of various foods. Because of the presence in such amounts of a cumulative poison like arsenic in foods against which regulatory officials are powerless to proceed, these officials must be doubly vigilant against those foods, such as sprayed vegetables, where the arsenic is unquestionably an added substance. The following table gives figures from this survey, limiting them to marine products because arsenic is, in general, much higher in these than in any other class of foods except those carrying spray residues. These data are given with the full recognition that the arsenic may, in some cases, be present in organic combinations which render it somewhat less toxic than when in the form of lead, calcium, or other arsenates. It is doubtful, however, whether any toxicologist would assert that there is any published work to prove that the natural arsenic in marine and other f@s is without any harmful physiological effect. PRODUCT Codfish
Eels
Haddock, smoked fillet Mackerel, fresh Prawns Sardines, canned Irish moss Clams Crab meat Lobster Oysters Shrimp
AsZOa Grains/lb. or pint 0.0140-0.0360 0.0180 0,0392 0.0136 0.1250 0.0105-0.0200 0.0140-0.0690 0.0104-0.0160 0.0140-0.0770 0.0160-0.1260 0.0100-0.0165 0.0170-0.0770
SAMPLES 3 1 1 1 1 5 7 6 17 4 6 5
Because of its bearing on the question of the assimilation of arsenic by fruit trees, Table I gives the arsenical content of the flesh of various fruits, both sprayed and unsprayed. By the term “flesh” is meant the fruit with peel removed. The results on whole apples and pears from an orchard, which had not been sprayed during the year the sample was taken, are of interest. This orchard had been heavily sprayed for many years previously. The data, as a whole, incline one to the tentative conclusion that traces of arsenic may reach the fruit through the sap, or by penetration of spray residues through the skin. This conclusion cannot, however, be drawn with certainty because there are two sources of error in determining amounts of arsenic of the order of 0.0007 grain per pound or less. One is the relatively large error of the Gutzeit test itself in this region. The other is the danger of contamination from hands, tools, glassware, and other sources, during the manipulation of the sample. It should be pointed out that arsenic results in the fourth decimal place me decidedly in the zone of “mere traces” and will be so reported unless the analyst has started with a sample of relatively enormous size.
ANALYTICAL METHODS The energies of the U. S. Department of Agriculture are being concentrated on the spray residue problem in all of its aspects, Among these might be mentioned efforts to develop less toxic insecticides which will yet give adequate control, restricting application of poisons to a safe limit and satisfactory removal of poisonous sprays by stripping, washing, or otherwke. Control by other means than spraying is, of course, not being overlooked, and it is still hoped that poison baits, cultural methods, attractants, and parasites may be
June, 1933
I N D U S T R I .4L
A N D E N G I N E E R I S G C H E hI I S T R Y
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T.4BLE I. ARSENICALCONTENT OF FRUITFLESH SOCRCE OF DATA Food & Drug Administration Fla. s t a t e Agr. Dept. (4) Fla. State Agr. Dept. (4) Food & Drug Administration Food & Drug Administration Food & Drug Administration Trans. Roy. Soc. S. Africa (S: Bur. Entomol. ( 8 ) Bur. Entomol. (8) Food & Drug Administration Food & Drug Administration Fla. State Agr. Dept. (4) Food & Drug -4dministration Fla. State Agr. Dept. (4) Fla. State Agr. Dept. (4) Food & Drug Administration Food & Drug Administration Food & Drug Administration Food & Drug Administration Food & Drug Administration Food & Drug Adm+ration (6) Food & Drug Administration ( 5 )
FRUIT Orange flesh Orange flesh Orange flesh Orange flesh Orange marmalstde Orange flesh Orange flesh Orange juice Orange juice Lemon flesh Tangerine flesh Tangerine flesh Grapefruit flesh Grapefruit flesh Grapefruit flesh Grapefruit flesh Lime juice Pear flesh Pear flesh Apple flesh Apples, whole Pears, whole
SPRAYHISTORY
AB208
Gram/lb. K O trace
Not known
0.00004-0.00055 Not known 0.00014-0.00126 Not known None Kone None i’ione None or trace 0 00007-0.0011 i’io trace hTo trace
0.00007
No trace None -0 .OO056 Trace -0.0004 KO trace None
0.0017
0 001 0.001,0.002
0.0007
0.0007
Not known
.......
1 sample sprayed Sprayed Lightly sprayed Heavily sprayed Not known Not known Not known Not known Not known Not known Not known Not known Heavily sprayed Heavily sprayed Heavily sprayed Not sprayed Not sprayed
useful allies in the fight against the insect hordes. The recent contribution of the Food and Drug Administration in the field of research has been along the lines of developing satisfactory micromethods for lead and fluorine. It was not until the beginning of the year that an accurate method for lead applicable to sprayed vegetables was available. The method is still time-consuming, but the hope is to shorten it materially. It is based on the wet combustion of the material with sulfuric and nitric acids, Jyhich precipitates the lead as sulfate. The filtrate may be used for an arsenic determination. The lead is dissolved in a special acetate solution which dissolves little or no barium sulfate. The lead is then precipitated as chromate, the chromate radical being determined iodometrically. Although not applicable to vegetables, a recently developed rapid approximate method for fruit may be of interest, since arsenic, lead, and fluorine may be determined in separate aliquots. The fruit, or other suitable material, is dipped in boiling alkali solution which generally removes the greater part of these three dements. (There is some evidence to indicate that this removal may be incomplete in some types of commercially washed fruit.) The color and waxes are removed by a special treatment with oxidizing agents. Interfering metals, such as iron and copper, are removed or converted into complex ions, and the lead is finally determined colorimetrically as dispersed lead sulfide in alkaline solution. It has been found possible to determine the lead in solution, when present in amounts corresponding to 0.02 grain per pound (about 3 p. p. m.) of apples, with an accuracy of 5 per cent. The work on micromethods for fluorine has not yet been carried to the point where a method of wide application has been developed. A preliminary report was presented a t the meeting of the Association of Official Agricultural Chemists last fall (10). Satisfactory results on vegetables have been obtained by isolating the fluorine according to the Willard and Winter technic (11). For quantities of fluorine too small to measure satisfactorily by the Willard and Winter titration with thorium nitrate, a preliminary distillation with sulfuric acid has been used, and then a modified Steiger-Merwin technic (8) has been applied to the final distillate. Influence of the hydrogen-ion concentration on the color of peroxidized titanium solutions was apparently not recognized-by Steiger and Merwin. The contribution of this laboratory has been the fixing of the optimum pH consistent with a reasonably straight-line relationship getween the fluorine content and colGr bleaching. Fair results may be obtained with Nessler tubes, but a photometer is necessary for most work. Stock colorimeters do not afford sufficient depth of solution for accurate readings. On fruits possibly a separate a!iquot of the stripping solution could be used for the approximate determination of fluorine as well as lead and arsenic. No distillation is neces-
SAMPLE5
3 9 20 2 5
5 Many
13 14 3 2 I 1
23 6 2 1 1 (peeled. was1led) 3 2 1
1
DATE
SOURCE Calif. Fla. Fla. Fla. 4 states
1933 1932 ueaeon 1931 seauon 1933
.... ....
Fla. Fla. Calif. Calif. Fla. Calif. Fla. Fla. Fla. England Colo. Colo. Colo. Colo. Colo.
sary here, the waxes and color being removed in a manner similar to that employed in the rapid lead method and the Steiger-Merwin method applied direct, with special technic to take care of the serious interferences of iron and aluminum. These and other interferences are discussed by Wichman and Dahle (10). In conclusion the following points are emphasized : 1, Federal jurisdiction cannot reach poisonous food within the borders of a sovereign state. It must be seized after it has been shipped or offered for shipment in interstate commerce, and the analysis and presentation of evidence to the Federal Courts must be so expedited as to impound the shipment before it is distributed. 2 . The responsibility of shipping wholesome food rests solely on the shipper and the receiver. This bureau has neither appropriation nor authority for service analyses or for compelling spray residue removal before shipment. 3. Court cases are prosecuted by the Department of Justice, and the punishment for violation is meted out by the Federal Courts. 4. Foods carrying spray residues of arsenic, lead, or fluorine cannot be impounded unless it can be established in court that food carrying the amounts actually found may be, beyond a reasonable doubt, dangerous to human health. LITERATURE CITED (1) Brit. Roy. Comm., “Rept. and Minutes of Evidence on A4rsenical
Poisoning from Beer and Other Articles,” Eyre &- Spottiswoode, 1903. ( 2 ) Bur. Entomol., unpublished data. (3) Copeman, Trans. ROQ.SOC.S. Africa,19, 107 (1931). (4) Fla. State Agr. Dept., data to be published. (5) Food and Drug Administration, unpublished data. (6) Myers and Throne, IND. ENQ.CHEM.,25,624 (1933). (7) Smith, M. C., Ariz. Expt. Sta., Bull. 32 (1931), 43 (1932). (8) Steiger and Merwin, J . Am. Chem. Soc., 30, 219 (1908); Am. J . Sci., 28,119 (1909). (9) Supreme Court, Dept. Agr. .V. J . 3398, Service and Regulatory Announcements, Chem. 7, Supplement, p. 603 (Jan. 11, 1915). (10) Wichman and Dahle, J . Assoc. Oficial AB?. Chem., 16, t o be published (1933). (11) Willard and Winter, IND.ENG.CHEM., Anal. Ed., 5 , 7 (1933). (12) Wright, Sappington, and Rantoul, J . Ind. Hug., 10, 234 (1928). RECEIVED March 29, 1933.
BRITISHINSECTICIDE MANUFACTURER REPORTS SATISFACTORY YEAR. Cooper, McDougall, and Robertson, the leading British producer of agricultural insecticides, sheep dip, and allied products, reported profits for 1932 operations as 133,000 pounds sterling, a gain of 20 per cent over 1931. This indicates that, despite the agricultural situation at home and abroad, agriculturists have been liberal in the use of pest-destroying agencies rather than risk the loss of stock or crops by false economy.
