UNITED STATES ENVIRONMENTAL PROTECTION AGENCY WASH I NGTON D.C ., 20460 

### APR 

## 2 9 

## 2015

MEMORANDUM OFF I CE OF PREVE N TIO N , PEST I CIDES ANO TOXIC SUBSTANCES



### SUBJECT: 

### BEAD Es timates for Applicator Exposu re to Ethoprop (PC Code: 04 I l 

### 0 l) 

### From App li ca ti ons Made t o Potatoes in th e Pacific Northwest.

FROM: 

### C layton Myers, Ph.D. , Bio log ist (

# ~ B iolog ical Analysis Branc h

# ~ B io logica l and Econom ic Ana lysis Di vision (7503P)

THRU: 

### Arn et J o nes, C hi ef Biological Analysis Bran 1 

### Biological and Economic Analysis Di v i s ion (7503P)

TO: 

### Eric Miede rh off, CRM Risk Management and Im p lementatio n Branch III 

### Pesticide Re-evaluation Di v i s ion (7508P) Matthew Lloyd , C IH Risk Assessment Branch VII H eal th Effects Divis io n (7509 P)

Product Review Pan e l : 

### April , 22 , 20 I 5

### S umm ary As part of a human hea lth ri s k assessment for reg istratio n review of e thoprop , OPP's Health Effec ts Divis ion (HED) i s eva luating potential ca ncer ri sks from occupa tiona l ex posure to eth opro p. Thi s m e m o provides estim ates fo r the ave rage/typical expos ure of pesticide applicators to ethop rop fo r usage on potatoes in th e Paci fic No rthwest, w hi c h HED h as iden tified as the driver scena r io for the chem ical's cancer risk assessment. Using US DA- NASS data for average potato fa rm sizes in the Pacific North west , a nd using information on the typical field sizes for potatoes in the same reg ion , BEAD estimates that a typical private applicator would apply ethoprop to potatoes abo ut 5 days per yea r. BEA D 's es tim ate is not upp er-bou nd , becau se HED re quires only an est imate of th e typic al/average ex po s ure. H owever , so m e i nh e re nt conse rva ti s m is b uilt into B EA D 's es timate, so that a ny bias o r e rro r from unc e rt a i nty is in the direction of being more protectiv e. W hil e BEAD do es not have direct access to in format ion o n co mmerc ial app li cati o n s of e th oprop, based o n input from industry experts and us i ng the same assumptions on field sizes and number of fields treated per day , B EA D qual it atively es tim ates t hat 5-8 application days per year co ul d be a reasonable estimate for commercia l app li cators of ethoprop o n p o tatoes in the Pac i fic Northwest.


### Background Ethopro p is an o rganophosphate ne m at icide/ in sec ti c i de that is labeled for use o n multiple agricultural crops in th e Un ited States, v ia soil- in corporated application. E th oprop is used on potatoes for contro l of nematodes a nd problematic soil insect pests such as wirewom1s (E P A , Proprietary Data , 

### 20 1 5; USDA- IP MC , 

### 2000). It is l abeled for one app l icat ion per year o n potatoes , and this application can e ith er be made at-planting, or post-harvest , and is sometimes co-applied w ith a f umi gant such as Vapam (WS PC , 

### 20 15). As part of a n occ up a ti o n al r isk assess ment fo r Reg is tration Review of e th oprop, HED is eval uating pote nti al ca n ce r ri s ks fr o m expos ure to cthoprop. Usage on pota to es in th e Pacific North wes t ha s been id ent i fied as a driver sce n ari o for th e occupationa l cancer ri s k assessment beca u se of the high app li cat io n rates used to con tro l nematodes, w hi ch B EAD has previously verified (informally). OPP's cancer risk assessments model the expected occupationa l chronic exposure over a 30 year worki ng period. HED has therefore indi cated th at they do n ot require upper - bound usage/ exposure es timates , but rather need an average or ' typical' estimate fo r the number of days pe r yea r an applicato r might app ly e th oprop to potatoes. In the absence of in for m a ti o n to inform appl icator exposure est im ates, HED re verts to an assu mpti on of 

### 10 app li ca tion days per year fo r pri vate app li cators a nd 30 ap p li catio n da ys per yea r for comm erc ia l app licators. This memo provides B EAD's es tim ates for the average/ t ypica l exposure of private pesticide app li cato rs to ethoprop from usage o n potatoes in the Pacific North west. While BEAD has no direct source of in forma t ion for commercial app li cators of e th oprop , a sur rogate qua litative e s timate for commercial applicat io n is also briefly discussed, based on in format io n provided to BEAD, H E D , and PRD from indu stry and commod ity experts (WSPC, 

### 2015).

2

### Meth od for Es t im at in g A ppli cat i o n D ays p er Y car To arrive at an ' average ' es ti m ate for typical priv a te ap plicator exposure days per year , B EAD es timates the average numb e r of e th o prop app li ca ti o n s p e r yea r (assumin g o ne app li cation per day) as the num ber of po tato fields per fa rm , furth e r ass umin g a ll fields are treated eve ry season. These two li sted assump tions inten ti onally int roduce a s ign ifi cant bias toward higher estimates of exposure. First, the ass umption th at every potato field is treated every year is an upper-bound usage assu mption , si nc e e th oprop can only be applied o nce per year to p o tatoes. Secondly, the assu mption that a fanner wo uld only app l y ethoprop to one field per day is pro tec t ive, because it is conceivable that more app li cations could be possible i n fewer application days ( HED assesses app lication days not th e number of application). Therefore, by inten tiona l design, BEAD 's es timates a r e biased i n a protective direc tion
. With further re gard to the upp e r-bound usage assu mpti o n , E P A's prop ri etary u sage informati o n indi cates that a very sma l l percentage of potatoes in Washington , O r egon, and Id aho a r e ac tu a ll y treate d with eth oprop o n a n ann u a l basis , w ith the average annual pe rcen t crop treated le ss th an 

### 5% for 

### 2009-2012 (EPA Proprietary Data) , in s tark contrast to B EA D 's assumption of l 

### 00 % treatm ent for potatoes. BEAD evaluated data on average fam1 sizes and average field s ize s to calculate an estimate of the ave rage n umber of fields present per farm , for commercia l potato fa r ms in th e Pacific No rthwest. Becau se a lmo s t all large potato farms in the Pacific Northwest are grown under ce nter-pivot sp rin k ler i rriga ti o n (US D A- IPM Cen ters, 

### 2000), BEAD furth e r ass um ed that the reported typical ' pivot ' size 

### ( 125 acres) is a reaso n ab le s urro gate for typica l field s ize for commercial potatoes grown in the Pacifi c Northwes t. Thi s est imate of t ypica l pivot s ize for production the Pacific Northwes t has been prov id ed to BEAD on n u merous occasions via informational tours , informa l commun ications wi th production and extension experts, and miscellaneous industry a nd exte n s ion li terature. T hi s estimate was a lso recently co nfirmed v i a communicat ion s w ith the Wash i ngton S tate Potato Comm ission (WS PC, 

### 2015). Dividing the average potato farm size by this average field size of 

### 125 acres then give s a reasonable approx imation of th e average number of field s pe r far m for P ac ifi c Northwest potatoes. Us ing 

### 200 7 and 

### 2012 da ta (US DA-NAS S, 

### 20 14), BEAD fir s t calculated a " raw " average farm s ize fo r potato farms in Washington , Oregon , a nd Id aho by d ivid in g the to tal reported potato acreage by the report ed tota l number of potato farms for eac h state. Next, BEAD used th e distribution of th e numb e r of farms b y s ize fo r these same four states to se lect the farm size ca tego ry that wou ld i nclude the median value for farm size. B ecause the mean value can be s i g nificantl y affected by the presence of many very small farms or a few very large farms, a median farm size es timate i s u sefu l for compari son a nd context, becau se the median provides the farm size value at th e m idd le of the farm size dis tribution
. A m ed ian farm s ize es tim ate could rea so nably be in terpre ted to be rep res e ntat ive 'ty pical ' of fa rm s izes, so lo ng as the di st ributi on of fa rm s izes i s reasonably close to norm a l. H oweve r, s ince fa rm sizes are o nly prov ided b y disc rete categories by NASS, BEAD cannot ide ntify the true median value , and ca n only se lect th e acreage rang e cohort/category whe re the m edian value wo uld be located. Fo r further protective bi as (i .e. , erring toward larger farm sizes, and thus m o re fields per farm and more applica t ion days) B EA D ' s presented distribution i nte n tionally omi t s a large number of sma ll potato fam1s less th a n 5 acres in size. Further, only processing potato acreage data is u sed



### 3for calculat ion of the 2012 estim ates, s in ce an overv iew of availab le data showed that proce ss in g farms tend e d to be larger on the w hole than farms producin g potatoes for th e fresh market (US D A-NASS, 2014). When comparing the average farm size w ith the respec ti ve range category fo r median farm size , BEAD then selec ted the hi g he r o f these two va l ues (and for a median range catego r y , selecte d the upp er limit ac rea ge va lu e from th e respective acreage cohort/category) to furth er bias the estimate toward large r far m size. Fina ll y, th e hi g hest est im ate for number of field s per farm ( i .e., app li ca tion day s p e r year) from all the states was se lected by BEA D as th e typica l value for a ll th e Pacific Northwest states. Tak e n in total, these factors a ll serve to bia s BEAD's esti mate s toward being m ore protective than wou ld be th e case if on ly the raw average va lu es were reported.


### Estimates from the 2007 a nd 2012 Censu ses of Agriculture For numerous vege tabl e crops , both th e 2007 and 2012 Censuses of Ag ri c ulture (US D A

-NASS , 2014) provide esti m ates for the number of farms and the total produ c tion ac reage by state. Addi ti ona ll y for potatoes, NASS pro v ides a frequency distribution by state fo r fann size. The 2012 Ce n s u s a l so pro v ides a breakdown of farm number s and tot a l acreage between fre s h m a rke t and proc essi ng production , in add ition to tota l production by s tate. This allows B EA D to provide es timate s for typic a l farm sizes that , while not upp e r-b o und , are inte ntion a lly biased toward larger fa rm sizes as described above, fo r the purpose of pro v idin g a more protective est im ate. Table 1 s hows th e farm size distribution data used to estimate the m ed ian potato farm size catego ri es for the 3 leadin g p o tato producti o n s tates in th e Pacific Northwes t : Id a ho, Oregon , a nd Wa s hin g to n (US DA-NA SS, 20 14). T able 2 shows the re sults for the ca lcu lat io n of th e average numb er of potato fields p e r farm.



### 4

### Table 1: Number of Farm by Farm Size Category and Average Acreage, Median Acreage , for Potatoes Grown in Idaho, Oregon, Wa s hington , and North Dakota in 2007 (all potatoes) and 2012 (processing potatoes only). Values in BOLD Used for Calcu lati on of Average N umber of Fields per Farm. * 2007 (All potatoes ) 2012 (Proce ss ing potatoe s only) # Farms by Acreage ID 

### OR WA TD 

### OR WA Category (Ac re s) 

### 5.0

- 14
. 9 7 7 11 3 I 

### 2 15
. 0-24
.9 12 14 8 6 0 0 25
. 0-49
. 9 43 19 16 24 15 6 50
. 0-99
.9 78 1 7 17 25 13 13 100.0-249
. 9 167 29 78 86 14 45 250
.0-499
. 9 135 20 42 71 1 1 43 500
. 0-749
.9 78 4 26 42 5 24 750.0-999.9 36 5 13 26 5 11 > 1000
.0 92 8 40 54 8 28 Total Acreage ( 1000 Acres) 

### 351 36 157 146 27 1 24 # Farms 

### 703 345 618 344 99 238 Avg
. Farm Size (A cres) 

### 499 104 254 

### 424 272 521 Med ian Farm S ize Category Upper Lim it 

### 500 250 

### 250 500 

### 250 500 (Acres) 

### *Sou rce: USDA-NASS , 

### 2014.
Tab le 2: Results for Average Number of F ields per Farm for Potatoes Grown in Idaho, 0 d 

## w h" t



### regon, a n as mg 

### on. 2007 (A ll potatoe s ) 2012 (Proce ss ing potatoe s only) ID 

### OR WA ID OR Typica l Farm Size 

### 500 250 254 500 272 Avg. Field Size (Acres) 

### 125 125 125 125 1 25 Avg. # F ield s per Fam1 

### 4.0 2.0 2.0 4.0 2
.2

Est im a te s for Commerc ial App lic ators BEAD doe s not have direct access to in fo rm ation o n commercial app li cations of e thoprop , other than limited ava il ab le proprietary info rm ation on ' w ho app li ed' ethoprop on a tota l pound s or total acreage basis by state (i.e., the r e is no t breakdown by individual app li cators, on ly an i ndicat ion on whether surveyed usage was done by a private applicato r or a commercial applicator). Among Pacific Northwes t states , data indicated th at mo s t app li cations made in Id aho and Ore gon between 

### 2009 and 

### 20 13 were made by private app li cators
. Fo r Washington , more ethoprop app li cations were made by commercial applicators (EPA , Proprietary Data)
. 

### 5 WA 

### 52 1 1 25 4
.2

### While it provides some basic context , this measure conveys no information on the actual number of fields treated by individual app li cators. However , information provided via phone conference to BEAD, BED, and PRD and v ia later follow-up correspondence with PRD (WSPC, 2015) in d i cated that most ethoprop applicati ons (espec ially at -pl anting) are done by private applicators
. A representative from a prominent commercia l contract application company in the Pacific Northwest further indicated that approximate l y 5 ethoprop applications per year o n potatoes would be typical for workers at that company. Anothe r industry representative from a compet ing contract app li cation company estimated that their commercial applicators would treat on average around 1 ,000 acres of potatoes per year with ethoprop
. Us ing BEAD ' s previously discussed estimate of 125 acres as an averag e potato field s ize for the Pacific Northwest , and retain in g the assumpt ion of treating one field per day , it follows that commerc i a l applicators with the second company would treat about 8 fields per year. Therefore, a qualitative est imate of 5-8 app li cation days per year may be a reasonab le approx im ation for commercial applicat io n s of ethoprop. However , BEAD reiterates here that it cannot independently verify such est imates in dependent l y , as there is no additional information available on ethoprop usage by commercial applicators that is current ly available to BEAD , beyond what had been obtained from industry experts as described previously (WSPC, 2015).
C onclu s ion Based upon analysis of availab le data for typical farm and fie ld sizes for potatoes grown in the Pacific Northwest , B E AD estimates that private applicators in this region wou ld apply ethoprop approximate ly 5 days per yea r, based on an intentionally biased , protective est imate of the number of fields per potato farm. This figure is derived from avai l able data from Washington , which had the largest mean potato farm s ize (521 acres). Taking this estimate and dividing by the typical fie ld s ize of 125 acres yi e lds an estimate of 4.2 potato fields per farm , which BEAD rounds up to 5. Assum in g one field is treated per day, and assum ing every potato field is treated every year (an upper-bound usage assumption), this translates to an est i mate of 5 app li cat ion days per year for private applicators of ethoprop on potatoes. BEAD does not have direct access to in formation on comme rc ia l app li cat ions of e th oprop. However , based on input from industry experts and using the same assumpt ions on field size and number of fields treated per day , BEAD estimates that 5

- 8 app li cation days per year cou ld be a reasonable surrogate , qualitative estimate for comm e rcial applica tor exposure to ethop rop on potatoes in the Pacific Northwest.



### 6

### Refe re n ces EPA, 20 1 5. Propr ietary Usage Data, 2009-20 1 3. USDA-IPMC , 2000. Crop Profile for Potatoes in Idaho
. USDA IPM Centers Crop Profile Document. www . ipmcenters.org/cropprofi I es/docs/ IDpotatoes.pdf USDA

- NASS, 2014. U.S. Department of Agr iculture, 2012 and 2007 Census of Agriculture: United States Summary and State Data Vo lume l, Geograph ic Area Series , Part 51. May 2014 , Table 38
. http ://www.aucensus . usda.gov/ Publications/ 2012/ Full Report / Volume 1 , Chapter I US / Washington State Potato Commission, 20 1 5
. Personal communication and discussion of issues and industry practices via phone conference with WSPC, BEAD , HED , a nd PRD
. March l 0, 2015.



### 7