,fer'I? ., Author Fire

5-p-CHLOROPHENYL SILATRANE, A NEW SINGLE-DOSE

Mr. Charles B. Beiter - Supervisor, Biochemical Products M & T Chemicals Inc. B.S. (Plant Science) Mr. Morton Schwarcz - Director of Research , Chemical Division M & T Chemicals Inc. B.S. (Chemistry) Mr. Glen Crabtree Assistant to the Director-Chemistry Denver Wildlife Research Center M.S. (Biochemistry) 5-p-CHLOROPHENYL SILATRANE. A NEW SINGLE-DOSE RODENTICIDE I In a recent issue of (August eradication program following placement of the 1969). Wi II iam D. Fitzwater. noted industry bait Consequently. a single dose rodenticide Is the lecturer and humorist, reviewed the folklore that most economical method of rodent control, has been accumulated through the years about requiring a minimum of man hours and batt rodents and, particularly, about rats and mice. The material to do the job. tales range from the use of mice in medicinal brews Although the have been the for curing a multitude of illnesses such as "snake dominant factor in rodent control for many years, bite, warts, epilepsy, poisoning, smallpox, recent reports from Scotland, England, Denmark, whooping cough, toothaches. and measles", to and the Netherlands have described field and spine-chilling tales of men being attacked and eaten laboratory experience with resistant alive by a cellar full of starving rats. You have also Norway rats. The spread of these resistant strains read about rats invading Park Avenue in Man could eventually result rn worldwide control hattan. the underground garage in Newark, and failures with anticoagulants, and cause a greater undoubtedly have seen the many stories about rats reliance on new single dose poisons. in slum areas. There are a number of disadvantages with Most of us have seen the Norway rat (Rattus existing single-dose which serve to norvegicus). the roof rat (Rattus rattus) and the limit their usefulness. Prebaiting is often needed to house mouse (Mus musculus). all of which live in obtain maximum effectiveness. More important, close association with man. They thrive in and near however, is the persistence of the rodenticide in city dumps, homes, restaurants, warehouses and the field after use. Strong public pressure is being food handling establishments. (Fig. A, B, C, D) exerted for tight controls on all pesticidal Much factual data has been gathered to establish chemicals which add long-lasting toxic residues to that rodents are not only a nuisance and an the environment. , for economic problem, but create a serious health example, is a highly effective but persistent hazard to man. They serve as carriers of diseases rodenticide. such as plague, typhus, rat-bite fever, and Another disadvantage of many quick-acting leptospirosis transmitted through fleas. bites and poisons is the " hazard." That the rodent excretion products deposited in water is, the killing of pets, domestic animals or birds, and foodstuffs. which may consume the dead rodent. Again, as an Other rodents such as the ground squirrel example, dogs or _cats eating a dead rodent killed :citellus beecheyi fisheri), the pocket gopher by sodium fluoroacetate, may in turn receive a (Thomomys, Geomys and Cratogeomys). and the lethal dose. Obviously, there is a definite need for a meadow mice (Microtus) are less important as less hazardous single-dose rodenticide. reservoirs of disease but can cause extensive M & T Chemicals Inc. has developed a new damage to agricultural crops. single-dose rodenticide currently designated as The use of a rodenticide, in conjunction with RS-1 SO•. good garbage disposal practices and proper con• RS-150 is 1-(p-chlorophenyl) 2, 8, 9-trioxa- struction of living and storage facilities, are the 5-aza-1-sila-bicyclo 13.3.3 I undecane, but for accepted methods for successful rat control. convenience we will call it by a more common Rodenticides are generally classified as single• name - 5-p-chlorophenyl silatrane. dose or multiple-dose according to their toxic action. Sodium fluoroacetate, , red squill and ANTU (alpha naphthylthiourea) are materials which fall into the first category. As indicated by this classification. baits containing single-dose rodenticides supply a fatal dose in a single feeding. The multiple-dose or cumulative rodenticides are comprised of the anticoagulants: Pival, , diphacinone, and fumarin. Continuous feeding by the rats for about 7 to 10 days is necessary to supply a fatal dose. The advantage of the use of a single-dose rodenticide is that it can provide immediate Cl reduction of large rodent populations. In general, 1-(p-Chlorophenyl) 2, 8, 9-trioxa•S-aza+s,labicyclo (3.3.3) undecane 24 to 48 hrs. are required for an effective TABLE I

2 •Patent applied for. FtgUre A Figure 8

Typical Rodent Harborage, City Dump - Louisiana Norway Rat Burrows

Figure C Figure D

Trash Attracts Rodents Rodent Droppings at Entry To Building

3 To the best of our knowledge, 5 p-chlorophenyl silatrane is the first pesticide ever developed with .!!l.ll(NIICIO( IIAlf fO!W\/1.ATIOl'ii. an organosilicon bond. RS 150 or p-chlorophenyl silatrane has been f98¥tJtA A registered for experimental use under USDA IN 3000 mg/ kg. INt;i!l£01l NU li lY WCIGHI p-Chlorophenyl silatrane is an odorless, white • 11111 CAN• I .. powder, thermally stable up to its melting point of folll ll•II 20 230-235°C. It Is soluble in , chloroform .... ,..,.,.5-1_, s and related organic solvents, but only slightly Con1 OIi s soluble - less than 0.02 grams per 100 ml - in H/ water. When dissolved in water, it hydrolyzes to !11. 100 form p-chlorophenyl siloxane and triethanolamine • S Kll',1 ectrteent,ac• """ ll I ltwtl of 10'\ which are non-toxic. The rate of hydrolysis is increased in the presence of acids. The hydrolytic TABLE Ill action serves as a basis for the self-detoxification The composition of the bait is critical to insure mechanism. acceptance by a specific rodent population. The The oral toxicity of 5-p-chlorophenyl silatrane acceptance of the formulations suggested here was has been studied with a limited number of animals, studied using white laboratory rats and mice, and which are reported in Table II. Only sparrows have corroborated by field tests. These in-house an LD lower than that found for Norway rats 5O investigations, in conjunction with field trials and mice. conducted in the vicinity of Baton Rouge, Louisiana, in the Iberville and West Feliciana ORAL TOXICITY OF S-,-CHLOROPHENYL SILATRANE TO MAMMALS Parish districts under the supervision of the State Health Service and the U. S. Department of the LO Interior, Bureau of Sport Fisheries and Wildlife, - 50 established that 0.25% to 0.5% 5-p-chlorophenyl

RATS (Norway. Laborl1oryl 1 - 41119\g silatrane is the optimum concentration for Norway rats. (Fig. El MICE (ubo11toryl 0.9 - 2 mg 'Ilg

BIRDS - Sparrows 0.2 - 0.4 mg kg The rodenticide must be added to the bait formulation immediately before use to insure Ma II ard Ducks 5 - 10 mg 'leg maximum effectiveness. (Depending upon Pintail Dudts 5 - 10 mg/leg environmental conditions and packaging to prevent MONKEY 14.0 mg/kg moisture absorption, baits may remain usable for two days.) In areas accessible to children and TABLE II domestic pets, the use of locked bait boxes is recommended. Torpedoes placed in burrows throughout a rodent infested area is also an Baits are made from a rodenticide concentrate effective means of baiting. (A torpedo is prepared containing 5% silatrane in sugar formulated with a by rolling 10-20 g. of bait in a small square of wax suitable food to a level of 0.25-0.5%. (Table I I I, paper.) Prebaiting, although not absolutely Formulations A & B) necessary, is desirable when practical. (Fig. F. GI

4 Figure E Figure F

Cage for Experimental Tests Bait Stations in Exposed Locations

Figure G Figure H

Baiting Burrows at Louisiana State Prison Norway Rats After Taking A Lethal Dose of 5-p• Chlorophenyl Silatrane

5 Caged wild Norway rats were cautious and under observed, whereas rats feeding on mice ad certain conditions would detect the rodenticide ministered a dose of 108 mg/kg of sodium before consuming a lethal dose. However, under fluoroaceta te died or exhibited typical symptoms field conditions, bait shyness has not developed. of sodium fluoroacetate poisoning. This is shown in Table V. The actual dose to the secondary Cooperative field studies under the supervision animal is calculated based on the amount of of the Division of Wildlife Services, Bureau of primary animal consumed. The results are particu Sport Fisheries and Wildlife presently underway in larly significant since the LO 50 rnnge of both Louisiana will establish the best procedure to be sodium fluoroacetate and 5 p Chlorophenyl followed in controlling rodent infestations in silatrane to white laboratory rats is between I and 5 dumps and other non residential areas. This work mg/kg. should be completed by the end of the year. IF,9 HI ..... Grain baits containing 0.25% 5 p chlorophenyl ,Wt!UJtrOFIUCllli'ICIEl:'lli si latrane remain effective for a period of three ,_..MfMl!IIIMJPlDfO ll:CO"IOM'f MNA&I U:ta;.,ur M•W days; then. the self detox1f1cat1on mechanism of IOOfJIIIIODt .. "'f I\.A'WIVOll 1UttD this unusual rodent1cide eliminates the hazard of IOU ,,_ ...... persistent residues. To illustrate this, white .. , u-u II ,. 111 NJ laboratory mice were offered a high protein grain -- •• ~, ., Jli ., • bait. The results in Table IV show a marked -·-...... •• -.,w-.. u -11.• ,.,. decrease in toxicity evidenced by an increase in fl'IUIJMWAU - 9'1Q - bait comsumption on the third week, and on the 11.COffWOAIY MIW.J - Ufl fifth week of storage, survival of all the test animals. Normal food intake was recorded after the TABLE V seventh week, insuring that the breakdown products do not affect bait acceptance. To minimize the detoxification of the rodentic1de in the primary test animal, they were sacrificed immediately after receiving the oral dose of the rodenticide and offered to the secondary JIOl.OG!CAL ASSArs :JN STI)lfQ IAIJS CONTAJNLNG 0,2$\ animal. It is very unlikely, however, that the poisoned animals would be available to the secondary animal in so short a period under field

STORAGE ,._ SUIIVIVOIIS TOTAL IAIIS ~- conditions. .!!!L_wms -IUTEO t!I _GIIAIIS Since the eating· habits of ground squirrels and 0 0 5 0.205 meadow mice are different from the Norway rat, it 0 '5 0.420 may be necessary to supply 5-p Chlorophenyl 2 0'5 ..... silatrane as a 100% active product for their control. I 5 UIS CJ 11.155 Recommended bait formulations consist of coating '5 5 '5 U.110 "squirrel oat groats" with the toxicant. A green 5 '5 HICO dye is normally added to discourage birds from eating the bait.

TABLE IV

This study might raise some questions regarding GROUND SOUIRRa BAIT FORMULA the stability of the rodenticide compound RS-150 and the rodenticide concentrate (5% active) prior INGREDIENTS PARTS to use. However, the biological and chemical stability of the rodenticide has been monitored for Squirrel Oat Groats 100 well over a year with no detectable reduction in Lecithin Mineral Oil (1 2.3) 2 activity. Monastral Green Dye 0.06 The lack of secondary hazard with 5-p-chlorophenyl silatrane to domestic pets is being S·p•chlorophenyl silatrane 0.5 established with laboratory rats and mice. When rats feed on mice dosed with a level greater than than 402 mg/kg, no toxic symptoms were TABLE VI

6 Figure I F19uro J

Ground Squirrel Burrows in Los Banos, California California Dept. of Agriculture Crew Dispensing 5-p• Chlorophenyl Silatrane Figura K Figure L

Gasoline Powered Bait Spreader Ground Squirrels After Taking A Lethal Dose of 5-p• Chlorophenyl Silatrane

7 The conditions for use of 5-p-chlorophenyl Field studies are continuing which will establish silatrane in the control of ground squirrels and procedures for control of Norway rats, ground field mice are being studied in California in squirrels, and mice. It Is hoped that sufficient cooperation with the State Department of support data will be available early next year to Agriculture, with the technical assistance of the obtain final registration with the USDA for control Denver Research Center, Bureau of Sport F 1sheries of these rodents. and Wildlife. Preliminary work in California has demonstrated that the bait is accepted by ground REFERENCES squirrels. Cage studies and field trials have Fitzwater, WIiiiam D., Rodent Folklor~ Pest substantiated the toxicity of the organosilicon Control, Vol. 37, No. 8, August 1969. rodenticide to the squirrels. Investigations are continuing to determine the adaptability of this Crabtree, D.G., Summary of Rodent Control poison to \he broadcast placement of the baits Methods and Materials. Information Circular on presently utilized in control of the rodents on Vector Control, No. 4, World Health Organ farmlands. ization, p.p. 20 25, Oct. 1964. Poisoning with 5-p-chlorophenyl silatrane is Lee, Jr. J.O., Regulation and Evaluation of evidenced by symptons of motor stimulation, Pesticide Products in the United States. agitated respiration, and clonic tonic spasms. The Proceedings Asia-Pacific Interchange - Rodents effect appears to be mainly on the stem portion of as Factors in Disease and Economic Loss, June the brain and spinal cord, but does not exert a 17-27, 1968. direct effect on the peripheral nervous system. Death generally occurs within 5 15 minutes after Baltkays, Ya., Voronkov, M. and Zelchan, G., consuming a toxic dose. No variation in the time Antranes 111 Brief Pharmacological Character and intensity of the reaction has been associated ization of Silatranes. lzv. Akad. Nauk Latviskoy with the age and sex of the rodents. SSR (Repts. Acad. Sci. Latvian SSR) No. 2 (199), 102-6 (1964). All the laboratory and field tests conducted on 5-p-chlorophenyl silatrane have demonstrated that Voronkov, M.G., Silatranes: Intra-Complex this product has the following desirable properties: Heterocyclic Compounds of Pentacoordinated 1. Effective fast-acting, single-dose rodenticide Silicon. Jour. Applied Chem. 13., 35 59 ( 1966). controlling Norway rats and ground squirrels. 2. Predictable self-detoxification in recom• Voronkov, M.G., Metalloatranes, A New Class of mended bait formulations. Ph s1olo icall Active Substances. Vestn. Akad. 3. No secondary hazard. Nauk SSR, 38 (10), 48-53 (1968).

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