Senator HART. You say in your statement "Should the teratogenic nature of 2,4,5-T be confirmed, registration for use on food crops will be canceled."

I am attempting to establish what will confirm it. What events do you look to to determine whether these preliminary indications which you say resulted from the contamination in fact did? Is there something in particular that you look to?

Dr. BAYLEY. Yes, the important considerations here are the usages for which the 2,4,5-T are permitted or which in actual practice are carried out.

The difference between the possibility of teratogenicity of the contaminate and the teratogenicity of the material that is used in the field is based on the rates of application, the losses which occur. All these effect the possibility of contamination of human beings.

Incidentally, my advice is that the one part per million level is at least tenfold below what they would consider a safe level in terms of allowances. In other words, that is the safety margin in this esti

mate.

Senator HART. In other words, there would have to be a finding of 10 times more?

Dr. BAYLEY. That is what I am told, yes. This is a statement based on scientific information provided to me.

Senator HART. Do you have any opinion as to whether Food and Drug might set a safe tolerance level in food?

Dr. Bayley. The action we have taken is to extend the time in which information can be provided or application made with Food and Drug Administration regarding the establishment of tolerances on food. I would not in any way want to prejudge what their actions should be, because it should be based on the data provided.

If I may elaborate on that, a petition was filed with the Food and Drug Administration in December of 1967 requesting the establishment of tolerances of 0.2 parts per million for residues of 2,4,5-T on apples, barley, blueberries, corn, oats, rye, sugarcane, and wheat. Those were the only crops to which that petition would apply.

The petitioner withdrew his petition on December 29, 1969, as provided under the pesticide regulations. We have extended to December 1970 the opportunity for him to provide the data needed to reach a decision on this.

There is one thing I think is important here, and that is the earlier reference to the concept of first, the burden of proof, and secondly, that we should not believe their data. We have to watch out for this paradox.

We in the Department of Agriculture, as you know, with the cooperation of the Food and Drug Administration, are not simply accepting the proof from industry in these cases. We are going out to obtain samples and testing them ourselves in order to verify the kind of information that is coming in.

Senator HART. I am not sure it is a paradox to say that the burden of proof is on the fellow that wants to expose the public to a product and some saying you cannot trust his data. They are two separate problems.

Dr. BAYLEY. I recognize that.

assumed that the data is reliable and matra mi et is st that the barben of pref may be on the KUT TO Ia ̈ De may be ce proposing D troduction of the

.

De 3.m. I susteet I am scsi- this because some people leg vir ve test products. We think I should be done in the Best The I seeded

water Eur. On the tamer of the Berin that was found to exist n the samples 1 1 112 lger perecting than the normal produc

We have been advised by Dow Chemical Company:

(1) That a sample of the 2,4,5,-T herbicide used in the Bionetics study contained 27±8 ppm of a highly active (biologically) contaminant, tetrachlordibenzo-para-dioxin. (This has been confirmed by the National Institute for Environmental Health Sciences.)

(2) That this material produced serious inflammation in rabbit ear tests and that the presence of the contaminant had been confirmed by chromatography. (3) That standard production 2,4,5-T contains less than 1 ppm of this contaminant and does not produce inflammation in the rabbit ear test.

(4) That Sprague-Dawley female rats as dams have been under test in their laboratory at Zionsville, Indiana, at five levels (25 rats each) of the standard production line material. They came to term January 7, 8 and 9, 1970, at which time they were killed by carbon dioxide inhalation and fetuses were removed by cesarean section and subjected to standard examinations for malformations and anatomical anomalies of various kinds; further examination will include clearing, staining and histopathologic procedures.

Dr. Howard L. Richardson, Chief, Pathology Branch, FDA, participated in the evaluation which related to full-term rat embryos subjected to 2,4,5-T during gestation, as well as a number of full-term rabbit embryos. He reports that no signs of malformations were found in gross and microscopic dissection of these embryos, but that histologic examinations are yet to be made. Personnel from the National Institute of Environmental Health Sciences were unable to participate, but will be involved in the examination of this and other informational material.

Further characterization of the contaminant tetrachlordibenzo-para-dioxin is currently under way and Dr. Leo Friedman will welcome participation by your research staff in this effort. We would point out the resemblance if not the "practical identity" of the tetrachlordibenzo-para-dioxin with the "chick edema factor." This substance is of extremely high toxicity to all species of animals that have been exposed, and until now, its source in contaminated fatty materials has been a mystery.

Considering the imminence of the availability of this additional information and the legitimate question as to whether or not the teratology reported by the Bionetics study was due to the 2,4,5-T or to the contaminant, we have elected to delay action on the petition for a few more days. As you know, the petitioner had requested, on December 5, 1969, an extension of 3 additional months.

We will advise you of our decision as soon as our scientific staff assays the results of this nearly completed test and considers them together with the results of other current research on 2,4,5-T at the National Institute for Dental Research and in the Food and Drug Administration. Thus far, no one has confirmed the Bionetics results although 2,4,5-T (with 27±8 ppm contaminant) has been found to be embryotoxic.

Sincerely yours,

JESSE L. STEINFELD, M.D.,
Surgeon General.

Senator HART. At the beginning of your testimony you say residues on food are unusual. When they do occur, are they the result of unauthorized use of 2,4,5-T or authorized use, or both?

Dr. BAYLEY. Mr. Chairman, I am going to ask Dr. Byerly to respond to that.

Dr. BYERLY. Sir, one of the two significant values, 0.19, was on milk, and the other was on sugar beets. As far as sugar beet use, I would have to verify whether or not there is a registered use on sugar beets. There is on sugarcane. There is certainly none on milk. This would be unauthorized use in the case of milk, certainly. Senator HART. Is it authorized for use on grass?

Dr. BAYLEY. Yes, sir.

Senator HART. It is?

Dr. Burzy. The law provides, and I will so pretend to quote it the mos c restritites including use, the Department fnis there is injury to people and to the environmentre estable enviromental cross the we can consider this is smoked mi anel the recSNUL

So the partem of the enfimement of that part of the law is for a male prgram to determine the extent to which their unautorrized uses are prou

This is very tany

and then we take action.

scine we rock recently involvaz sapoend It was this type

creating in my and we

thorized on grass, not milk.

Senator Fan Year the s Comid not cows ett grass this producing rest dives in our milk. IR. FARLEY. This a lused on the fontenditions for use and also based on the degradation properties of Lab-I is. Good pracald require withholding the grazing of cows from these pasbe no residue in The widespread use of this as berbicide on ranges and pastures Diates at farmers ar fo practices with the possible the exœption that we know

the anims product.

we

Sematir Hrn. What information dan voru ald to this record substantiating the staterent that had I Seg

atter of-how

Ir. Fine. We will be glad to supply for the round the scientide information idioting the degradition time of 245-T as well As the circumsans under

Senator Horn. Tist w be printed in the reoerd.

The mammation follows (

[From: Chemical Fallout-Current Research on Persistent Pesticides Ed. by Morton W. Miller & G. G. Berg. Charles C. Thomas, Publisher. 1969]

Soil Persistence of 2,4,5-T

The persistence of 2,4,5-trichlorophenoxyacetic acid (2,4,5-T), when applied at recommended rates (0.25 to 8 lb/A) is 4 to 5 months as compared to about 1 month for 2,4-dichlorophenoxyacetic acid (2,4-D) as shown in the figure below.

DeRose (3) found that a 3 lb/A field application of 2,4,5-T was no longer phytotoxic to soybeans 3 months later. However, rates of 10 and 20 lb/A remained highly phytotoxic after 3 months. Newman, et al (4) found that 2,4,5-T lost its phytotoxicity after 4 months when applied at rates up to 26 lb/A. Burger, et al (1) found a similar loss of phytotoxicity to alfalfa 4 months after the application of 25 ppm (50 lb/A). However, these were both laboratory studies in which the soils were maintained moist and warm, two conditions that facilitate the microbial inactivation of phenoxyacetic acid herbicides. The 6 month persistence of 2,4,5-T in soil, DeRose and Newman (3), appears to be one of the largest persistences reported.

Microorganisms are primarily responsible for degrading phenoxyacetic acid herbicides in soils. The kinetics of 2,4-D, 2-methyl-4-chlorophenoxyacetic acid (MCPA), and 2,4,5-T detoxification in soil-perfusion experiments were exactly what would be expected if microorganisms were the detoxicating agents (4); in addition, detoxication was blocked by the bacterial inhibitor sodium azide. The bacteria and actinomycetes responsible for degrading phenoxyacetic acids are shown in Tables 1-2 (4). The metabolism of the phenoxyacetic acid herbicides has been studied extensively (4). There appear to be two major pathways of degradation, i.e., via a hydroxyphenoxyacetic acid intermediate and degradation via the corresponding phenol. Some of the important steps in microbial metabolism of representative phenoxyacetic acids are shown in Figures 1-6 (4).