Class B Biosolids

Class B Biosolids is a designation for treated sewage sludge that meets U.S. EPA guidelines for land application as fertilizer with restrictions that are noted below. Compared to Class A Biosolids, Class B Biosolids are allowed to have detectable pathogens. All other regulations for contaminants in the two classes are the same. Despite the U.S. EPA's assurances of safety,, the safety requirements for Class B Biosolids are insufficient to ensure safety. Animals fed forage crops grown in soil fertilized with Class B Biosolids have died and humans working in the fields where Class B Biosolids were applied have been sickened.

U.S. EPA Standards for Metal Contaminants in Class B Biosolids
The U.S. EPA sets limits for concentrations of ten metals in sewage sludge classified as Class B Biosolids. All concentrations listed are dry-weight concentrations:
 * Arsenic: 75 parts per million (ppm)
 * Cadmium: 85 ppm
 * Chromium: 3000 ppm
 * Copper: 4,300 ppm
 * Lead: 840 ppm
 * Mercury: 57 ppm
 * Molybdenum: 75 ppm
 * Nickel: 420 ppm
 * Selenium: 100 ppm
 * Zinc: 7,500 ppm

Restrictions on Use of Class B Biosolids
Class B biosolids may not be applied to home lawns and gardens. Additionally, the following restrictions apply:


 * "Restrictions for the harvesting of crops and turf:
 * 1. Food crops, feed crops, and fiber crops, whose edible parts do not touch the surface of the soil, shall not be harvested until 30 days after biosolids application.
 * 2. Food crops with harvested parts that touch the biosolid/soil mixture and are totally above ground shall not be harvested until 14 months after application of biosolids.
 * 3. Food crops with harvested parts below the land surface where biosolids remain on the land surface for 4 months or longer prior to incorporation into the soil shall not be harvested until 20 months after biosolids application.
 * 4. Food crops with harvested parts below the land surface where biosolids remain on the land surface for less than 4 months prior to incorporation shall not be harvested until 38 months after biosolids application.
 * 5. Turf grown on land where biosolids are applied shall not be harvested until 1 year after application of the biosolids when the harvested turf is placed on either land with a high potential for public exposure or a lawn, unless otherwise specified by the permitting authority.


 * "Restriction for the grazing of animals:
 * 1. Animals shall not be grazed on land until 30 days after application of biosolids to the land.


 * "Restrictions for public contact:
 * 1. Access to land with a high potential for public exposure, such as a park or ballfield, is restricted for 1 year after biosolids application. Examples of restricted access include posting with no trespassing signs, and fencing.
 * 2. Access to land with a low potential for public exposure (e.g., private farmland) is restricted for 30 days after biosolids application. An example of restricted access is remoteness."

Related SourceWatch articles

 * Biosolids
 * Sewage sludge
 * Food Rights Network

External resources

 * EPA Guide to Part 503 Rule, Chapter 2, Land Application of Biosolids, U.S. EPA.