Guidance for Controlling Potential Risks to …

1 Guidance for Controlling Potential Risks toWorkers Exposed to Class B BiosolidsThis Guidance is intended only for Controlling health Risks to workers fromClass B biosolids during handling and land application. This Guidance is notintended to address nonoccupational OF HEALTH AND HUMAN SERVICESC enters for Disease Control and PreventionNational Institute for Occupational Safety and HealthJuly 2002 SAFER,HEALTHIER,PEOPLEDISCLAIMERM ention of any company or product does not constituteendorsement by INFORMATIONTo receive documents or more information about occupationalsafety and health topics, contact the National Institute forOccupational Safety and Health (NIOSH) atNIOSH Publications Dissemination4676 Columbia ParkwayCincinnati, OH 45226 1998 Telephone:1 800 35 NIOSH(1 800 356 4674)Fax: 1 513 533 8573E-mail.

2 Visit the NIOSH Web site Number 2002 149 This document is in the public domainand may be freely copied or are the organic residues resulting fromthe treatment of commercial, industrial, andmunicipal wastewater (sewage). One purposeof the treatment is to significantly reduce theconcentration ofdisease-causing organisms (alsoknown as pathogens). Treatment also reducesthe attractiveness of the residues to insects,birds, and rodents. The product is a materialthat can be recycled for uses such as addingorganic material to the Environmental Protection Agency (EPA)has established two categories of biosolids: Class A biosolids have undergone treat-ment to the point where the concentrationof pathogens is reduced to levels low enoughthat no additional restrictions or special han-dling precautions are required by Federalregulations [40 CFR*Part 503].

3 If the Class Abiosolids meetexceptional qualityrequire-ments for metals content, they may besold in bags and applied in the same wayas other soil conditioners such as peatmoss. Class B biosolids have undergone treatmentthat has reduced but not eliminated patho-gens. By definition, Class Bbiosolids maycontain pathogens. As a result, Federal reg-ulations for use of Class B biosolids requireadditional measures to restrict public accessand to limit livestock grazing for specifiedtime periods after land application [40 CFRPart 503]. This allows time for the naturaldie-off of pathogens in the EPA rules [40 CFR Part 503] restrictpublic access to lands treated with Class Bbiosolids in order to protect public health, theserules do not apply to workers involved withClass B biosolids handling and land application.

4 *Code of Federal may come in contact with Class Bbiosolids during the course of their work. Workersand employers may be well aware of the needfor precautions when contacting untreated sew-age but less aware of the need for basic precau-tions when using Class B biosolids. This docu-ment provides information, Guidance , andrec-ommendations to employers and employees work-ing with Class B biosolids to minimize occupa-tional Risks from pathogens. It does not addressother Potential safety and health issues such asinjuries or exposures to are biosolids used?Biosolids are typically treated to Class B orClass A standards at the wastewater (sewage)treatment plant, where a liquid or semi-solidmaterial is produced. In a liquid state, biosolidscan be transported by truck to a land applica-tion site where they are applied directly tothe land using tractors, tank wagons, irrigationsystems, orspecial application vehicles.

5 Alter-natively, biosolids may undergo mechanicaldewatering that may include the use of poly-mers. Dewatered and liquid biosolids are oftentemporarily stored at the treatment plant orapplication site. Dewatered biosolids are trans-ported and applied to land using front-end load-ers,trucks, tractors, or biosolids-spreading equip-ment. Most biosolids are applied with spreadersin semisolid form and then incorporated into thesoil using a disc plow. Workers may come intoeither direct or indirect contact with biosolidsduring any phase of the treatment, transport, orapplication process, or after they are land ap-plied. Currently, more than 50% of the biosolidsgenerated in the United States is recycled as soilconditioners to improve and maintain productivesoils and stimulate plant growth rather than beingsent to landfills or incinerated.

6 Biosolids are ap-plied on agricultural land, forestlands, and sur-face mine reclamation sites. Class A biosolidsare also used in horticultural applications. EPAestimates that million tons of biosolids weregenerated for use or disposal in is in biosolids thatrequires control of workerexposures?There are four major types of human disease-causing organisms (pathogens) that can be foundin sewage: (1) bacteria, (2) viruses, (3) protozoa,and (4) helminths (parasitic worms). Class Bbiosolids may contain the same types of patho-gens as the source sewage, but at reduced con-centrations. Both Class A and Class B biosolidsmay also contain chemicals (including metals)and protect public health, the EPA s 40 CFRPart 503 rule prescribes arestricted periodofup to 1 year to limit public access to landswhere Class B biosolids have been EPA restrictions do not apply to occupa-tional access.

7 EPA does recognize that occupa-tional exposure can occur and states that workersexposed to Class B biosolids might benefit fromseveral additional precautions such as use ofdust masks when spreading dry materials, theuse of gloves when touching biosolids, and rou-tine hand washing before eating, drinking, smok-ing, or using the risk of worker exposure to infectious agentsin Class B biosolids is likely greatest prior to,during, and immediately after land applicationof the biosolids. Because the concentration ofpathogens declines through natural processes,the Potential for pathogen exposure decreasesover we know thesepathogens can causedisease?Yes, the association between poor hygiene, rawsewage, and infectious disease is well estab-lished. Most of the pathogenic bacteria, viruses,and parasites in biosolids are enteric, whichmeans they are present in the intestinal tracts ofhumans and animals.

8 Enteric organisms that maybe found in biosolids include, but are not limitedto,Escherichia coli,Salmonella, Shigella,Campylobacter, Cryptosporidium, Giardia, Norwalkvirus, and enteroviruses. Exposure may poten-tially result in disease ( , gastroenteritis) or in acarrier state in which an infection does not clini-cally manifest itself in the individual but can bespread to others. These enteric organisms are usu-ally associated with self-limited gastrointestinalillness but can develop into more serious diseasesin sensitive populations such as immune-compro-mised individuals, infants, young children, andespecially the disease risk is a function of the number andtypes of pathogens in the Class B biosolids rela-tive to the exposure levels and infective data are sparse on what constitutes aninfective dose, it is prudent public health prac-tice to minimize workers contact with Class Bbiosolids and soil or dusts containing Class Bbiosolids during production and application, andat land application sites during the period whenpublic access is restricted.

9 Class A biosolidsmay also present some health risk to workers,since some chemicals and biologic constituentsin Class A biosolids are not regulated by workers be exposed topathogens from biosolids?Workers could be exposed to pathogens and ir-ritants when working with Class B biosolidsduring the period when public access is re-stricted. During a NIOSH field investigation atone biosolids land application and storage sitethat did not comply with EPA requirements, thefollowing was observed: NIOSH interviewed employees whoworkedin all phases of the biosolids operation. Some2employees reported repeatedepisodes ofgastrointestinal illness afterworking withthe biosolids, either at the treatment plantor during land application. NIOSH observed among workers an in-consistent awareness, provision, and useof protective equipment and hygiene prac-tices appropriate for handling Class Bbiosolids (or biosolids that do not complywith EPA standards).

10 NIOSH collected bulk samples from dif-ferent locations within the biosolids stor-age site and found measurable concentra-tions of fecal coliforms. Fecal coliformsare used as an indicator for the presenceof other enteric microorganisms. Entericbacteria were detected in air samples col-lected at the land application site. The local department of environmentalservices recently informed NIOSH thatbiosolids applied at this site intermittentlyexceeded (by up to times) the EPAfecal coliform upper limit for Class Bbiosolids prior to the NIOSH survey. The substandard biosolids were applied atthe agricultural site before the monitoringresults were received from the reports that high-pressure spray applica-tions may result in some aerosolization ofpathogens and that application or incorpora-tion of dewatered biosolids may cause verylocalized fine particulate/dusty conditions.