Quantity of Antimicrobials Used in Food Animals in the

United StatesCharles M. Benbrook

Consultant to theUnion of Concerned Scientists

101st Annual MeetingAmerican Society for Microbiology

May 22, 2001

Released Jan. 8, 2001

Access text at:

http://www.ucsusa.org

METHODOLOGY

Use estimates developed for swine, beef cattle and

broiler production

Reflects antimicrobial use in the mid- to late 1990s

METHODOLOGY

Use Antimicrobial x =

Number of animals treated x

x Average days treated x

x Average dose x

DATA SOURCES

Average number of animals produced annually in the late 1990s from USDA inventory data

29 million beef and veal calves

92.6 million hogs

7.8 billion chickens

DATA SOURCES

Percent of animals treated with different antibiotics by the USDA National Animal Health Monitoring System (NAHMS) and NAS reports

Data quality on extent of use better for beef and swine, less complete for poultry

METHODOLOGY

Developed antimicrobial use estimates during each major growth stage

Total feed consumed during each growth stage calculated from widely accepted estimates of feed efficiency and weight gain

METHODOLOGY

Antimicrobial use in each growth stage projected from NAHMS data and CFR Indications and ‘Conditions of Use’ in the FDA ‘Green Book’

Days fed and average dose rates adjusted downward from maximum allowed based on common industry practice and expert advice

FINDINGS

Beef and Veal Antimicrobial Use

Estimated Antimicrobial Use in Pounds

Calves (birth -> 250 pounds) 45,511

Beef (250 - 500 pounds) 164,051

Backgrounder (500-700 pounds) 1,421,277

Feedlot (700 - 1,200 pounds) 2,055,237

Veal Calves 6,941

Total Cattle Industry 3,693,017

FINDINGS

Poultry Production Antimicrobial Use

Estimated Antimicrobial Use in Pounds

Pre-starter & Starting 2,658,081

Growing & Finishing 7,877,845

Total Poultry Industry

10,535,926

FINDINGS

Swine Production Antimicrobial Use

Estimated Antimicrobial Use in Pounds

Starting (15 - 40 pounds) 1,254,943

Feeding (40 - 100 pounds) 1,757,249

Finishing (100 - 240 pounds) 7,279,080

Breeding animals 57,324

Total Swine Industry

10,348,596

FINDINGS

Total Annual Antimicrobial Use

Total Use Percent(pounds) Total Use

Beef 3,693,017 15.0%

Swine 10,348,596 42.1%

Poultry 10,535,926 42.9%

24,577,539

FINDINGS

Trends in Antimicrobial Use per Animal

1985* Late 1990s Percent Change

Beef 2,889,573 3,693,017

28%

Swine 11,710,650 10,378,596 -

11.6%

Poultry 3,436,140 10,535,926

307%

18,036,363 24,577,539 36.3%

* 1985 use assuming the number of beef cattle, swine, and poultry produced in 1984 equaled late 1990s herd/flock size.

FINDINGS

Trends in Tetracycline Use per Animal

1985* Late 1990s Percent Change

Beef 1,442,780 731,520

-49%

Swine 3,890,980 4,972,213

28%

Poultry 485,667 1,418,675

192%

* 1985 use assuming the number of beef cattle, swine, and poultry produced in 1984 equaled late 1990s herd/flock size.

“Conventional Wisdom”

Annual Estimates prior to ‘Hogging It’

Total use (per NAS) = 50 million pounds

Total use in agriculture (per AHI) =

17.8 million pounds

Total use in humans (calculated) =

32.2 million pounds

PLACING USE INTO PERSPECTIVE

DATA SOURCES

50 million total use extrapolated from 1985 IOM estimates, in turn based on very incomplete data

Legitimized through repetition; including on CDC website (until recently)

No basis in fact; a myth

METHODOLOGY

Medical (Outpatient & Inpatient) Human Use Estimates based on:

Number of courses of treatment

times the average dose delivered

METHODOLOGY

120 million courses of treatment

Two doses per day for 10 days

Dose rate between 250 & 500 mg

5-10 grams of antimicrobial per course of treatment

Outpatient Use Estimate

METHODOLOGY

50 million courses of treatment

Average 8 days per course

250 mg (low end) to 500 mg (high end) per dose

Inpatient delivery (injection or IV) more efficient but average patient is also sicker, so same dose range as outpatient use

Inpatient Use Estimate

FINDINGS

Antimicrobials Used in Human Medicine

Low End High End Most Likely Value

Outpatient Use 1,322,774 2,645,547

2,100,000

Inpatient Use 551,156 1,102,311

900,000

Total Treatment 1,873,930 3,747,858

3,000,000

*Table 2, ‘Hogging It’, p. 17.

AHI 2000 Estimates

Use Percent TotalAnimal Use

Animal Therapeutic 14.7 82.6%and Disease Prevention

Animal Growth Promotion 3.1 17.4%

17.8 million pounds

Total Animal Use as Percent of 50 million = 36%Total Human Use as Percent of 50 million = 64%

PLACING USE INTO PERSPECTIVE

UCS Estimates

Total Percent Pounds Total Use

Human Uses Inpatient 900,000 3%Outpatient 2,100,000 6%

Total Disease Treatment 3,000,000 9%Other Human Use 1,500,000 4%

All Human Uses 4,500,000 13%

PLACING USE INTO PERSPECTIVE

Shares of Total Antimicrobial Use

AHI UCS

PLACING USE INTO PERSPECTIVE

Conventional Wisdom

Animal 36% 84%

Human Medicine 64% 9%

Other ----- 7%

Non-Human Antimicrobial Use Total Percent

Pounds Total UseLivestock Uses

Non-therapeutic (3 species) 24,600,000 70%

Non-therapeutic (other) 3,000,000 8.5%

Therapeutic (all species) 2,000,000 5.7%Pesticide Uses 50,000 0.1%Companion Animals 1,000,000 2.8%Total Non-Human Uses 30,600,000 87%Human Use 4,500,000Total Use 35,100,000

PLACING USE INTO PERSPECTIVE

CONCLUSIONS

Animal use accounts for the majority of total antimicrobial use

Pounds used in treating largely healthy (although stressed) animals exceeds human use about 8 to 1

FINDINGS

13 million pounds of antimicrobials used for nontherapeutic purposes in raising beef, swine and poultry are drugs that are no longer approved in Europe for such uses

FINDINGS

Class I: Used to treat human disease, few or no alternatives

Class II: Used to treat human disease, alternatives exist

Class III: Not currently used to treat human disease

Animal Uses of Antimicrobials by

Importance in Treating Human Disease

FINDINGS

Nontherapeutic Antimicrobial Uses in Livestock by Relative

Importance in Treating Human Disease

Cattle Swine Poultry TotalClass I 18,181 7,492 574,435 600,108 Class II 1,458,804 9,788,870 1,683,064 12,930,738 Class III 2,216,032 552,234 8,278,427 11,046,693

Total All Classes 3,693,017 10,348,596 10,535,926 24,577,539 Percent of Total 15% 42% 43%

FINDINGS

Nontherapeutic Antimicrobial Uses in Livestock by Relative

Importance in Treating Human Disease

Cattle Swine Poultry Total

Erythromycin 18,181 381,753 399,934 Virginiamycin 7,492 192,682 200,174 Total Class I 18,181 7,492 574,435 600,108Class I as % of Total 0.5% 0.1% 5% 2%

Class I: Used to Treat Human Disease, Few or No Alternatives

FINDINGS

Nontherapeutic Antimicrobial Uses in Livestock by Relative

Importance in Treating Human DiseaseCattle Swine Poultry Total

Chlortetracycline 588,042 4,007,632 1,418,675 6,014,349Bacitracin 25,885 1,894,450 96,728 2,017,063Tylosin 356,999 943,635 1,300,634Oxytetracycline 143,478 964,581 1,108,059Sulfathiazole 901,251 901,251Sulfamethazine 344,400 455,434 799,834

Penicillin 528,777 141,867 670,644

Lincomycin 53,685 25,794 79,479

Apramycin 39,425 39,425

Total Class II 1,458,804 9,788,870 1,683,064 12,930,738

Class I & II as % of Total 40.0% 95.0% 21% 55%

Class II: Used to Treat Human Disease, Alternatives Exist

RECOMMENDATIONS

FDA should require antimicrobial use data by species, class, disease, delivery system and treatment period

RECOMMENDATIONS

USDA should improve completeness and accuracy of periodic use surveys

RECOMMENDATIONS

Speed up Priority Action 5 -- establishment of usage monitoring and information sharing system