Subject: RUFUS CHANEY ON THE RISK TO LIVESTOCK FROM TOP DRESSING/SURFACE
DISPOSAL OF SEWAGE SLUDGE COWS CATTLE COBALT ALUMINUM AND MANGANESE
EXCERPTS FROM INTERVIEW TRANSCRIPT
DR. RUFUS CHANEY, U. S. DEPT. OF AGRICULTURE, ENVIRONMENTAL CHEMISTRY LAB -
FEBRUARY 7, 2002
CALL FROM: ERIK APEDAILE, SUSAN LIVER, IRWIN OSINGA
SUBJECT: CANADIAN REVIEW OF HEALTH ASPECTS OF BIOSOLIDS LAND APPLICATION
EXCERPTS FROM STATEMENTS MADE BY DR. CHANEY:
"But when the fluid biosolids are spray applied on standing forages,
the biosolids particles can get stuck to the forages . . . when such
contaminated forages are grazed, livestock can get high exposure to
xenobiotics in biosolids." (Studying the
Metabolism and Disposition of Chemicals in Biological Systems - xenobiotics
include such substances as TNT, PCBs, chlorophenols and PAHs.)
If dewatered biosolids or composts are land applied, the biosolids fall
to the soil surface rather than get spread out on leaves and stems of
forages, and exposure is hardly different from the ingestion of surface soil
If the biosolids are incorporated into soil, uptake to forages is low,
but soil ingestion does allow some livestock exposure and absorption of
xenobiotics. Grazing (not forage uptake) by animals could be getting these
compounds into food and milk, especially if the biosolids are surface
IO: So a BMP (Best Management Practice) would be to not apply
biosolids to pastureland?
Dr. Chaney: 'The BMP IS TO INCORPORATE THE BIOSOLIDS IF THE FIELD WILL
BE USED FOR PASTURE. Biosolids can represent 12% of an animal's diet if
fluid biosolids are surface applied . . . << 1% if incorporated (animals
consume about 1.5% soil on yearly average basis; and if the biosolids are
mixed with soil, the surface soil to which they have access contains greatly
EA: In Ontario soil pH needs to be 6.
R. Chaney: "Reg 503 doesn't have a pH limit, But the EPA reg assumes
that if the soil pH falls below 5.5 that the farmer needs to deal with Al
and Mn (aluminum and manganese) toxicity in the soil by adding limestone . .
. . at 5.2 (pH) you get yield reduction from Al toxicity . . . "
"I also suggested risk assessment for Co (cobalt) just to check that we
don't have a rare high Co risk in sludge in a particular area. Plants can
take up enough Co to harm ruminant livestock under worst case model
EA: What are the implications of this for Ottawa?
Dr. Chaney: "I THINK YOU SHOULD MAKE AN ISSUE OF VOLUNTARILY GIVING UP
THE RIGHT TO SURFACE APPLY LIQUID BIOSOLIDS. At least Ottawa needs to
recommend incorporation, recommend tillage to incorporate the biosolids
before growing a crop, which would be grazed.
Incorporation reduces potential exposure (worst case models)
remarkably. . . . If you give up pasture land it reduces flexibility. I
RECOMMEND AS A GUIDANCE ALL BIOSOLIDS BE INCORPORATED BEFORE GRAZING
OCCURS. Standing crops with sprayed liquid can result in 25% sludge in diet.
INCORPORATION RESULTS IN LESS EXPOSURE FOR METALS, ORGANICS,
PHARMACEUTICALS, AND ODOUR. It is a BMP!"
RECOMMENDED METAL LEVELS IN SEWAGE SLUDGE:
"Although the higher limits of 503 can be tolerated by society, but if
you can avoid putting these metals down the sewer it's better. We have
recommended "attainable" levels, e.g. Hg (mercury) 2-5 mg/kg vs. 20 mg/kg in
Reg. 503 ---- 500 mg/kg Cu (copper) vs. 1600 ppm in 503, etc. The
"attainable" levels are always better than the max allowed by 503."
"Fe (iron) in biosolids is typically about 20,000 mg/kg dry weight.
Our work found biosolids causing harm to cattle when fluid biosolids were
surface applied on pastures, which contained about 120,000 mg Fe/kg (12%).
Ferrous was solublized in the rumen. It induced copper deficiency in the
cattle. . . . only spray applied fluid biosolids was an issue. The 30-day
waiting period would be important to minimise transfers from surface applied
"AGAIN, THE IDEA OF INCORPORATION IS IMPORTANT -- PARTICULARLY
REGARDING THE IDEA OF UNKNOWN ORGANICS -- INCORPORATION REDUCES THE
TRANSFER TO LIVESTOCK VERY STRONGLY."
Presentation arranged by:
Gregory K. Evanylo
Professor and Extension Specialist
Crop and Soil Environmental Sciences (0403)
426 Smyth Hall, Virginia Tech
Blacksburg, VA 24061
Ph: 540/231-9739; Fax: 540/231-3075