revised biosolids ppt

BIOSOLIDS

Examining the risks associated with the land application of biosolids: incidental ingestion from hand-mouth transfer

Team members:1. Dr. George Varghese2. Dr. Sanjay Gupta3. Dr. P. Uma Devi4. Subodhika Vohra

INTRODUCTION• Biosolids are nutrient-rich organic materials

obtained from the treatment of domestic wastewater in a wastewater treatment facility.

• Biosolids are rich source of organic matter, Nitrogen, Potassium and Phosphorus, iron therefore assists in the improvement of soil structure thus can be used as bio-fertilizer.

• Biosolids usually are applied at rates designed to supply crops with adequate nitrogen, phosphorus and micro-nutrients; that reduce fertilizer requirements.

•Due to sewage sludge origin, biosolids contains a number of human enteric pathogens, including bacteria, viruses, and parasites.

•The levels of such pathogenic contaminations depends on the pathogen burden in a particular country, the volume of sewage produced, and the type of treatment of the biosolids.

•Therefore the pathogens load in biosolids may vary greatly in different geographical regions and country to country.

• Due to high pathogenic potential, biosolids are getting treated before use.

• The land application of biosolids that have not been treated to remove all human pathogens poses serious threat to the farmers and workers through direct human contact contaminations, including hand contact.

• Hand contact with biosolid-amended soil followed by hand-to-mouth contact and accidental ingestion creates a route for enteric infection in people who come in close contact with agricultural land.

• The most obvious risk group for this exposure is the farmers and workers, either when applying them to land or working on land where application has taken place.

PROBLEM FORMULATION

•The problem addressed in this study is quantification of the risk posed to human health by the practice of applying bio-solids to land.

•The pathogens present in the bio-solids can infect the human being exposed to the practice through various pathways.

Source: (Oun, Kumar, Harrigan, Angelakis, & Xagoraraki, 2014)

As there are various pathways of exposure and a number of micro-organisms affecting, only a specific case of adenovirus exposure through ingestion and its risk assessment is addressed in this study.

SCOPE

• Previous studies have shown that adenovirus was the pathogen that presented the greatest risk across the different pathways (Gurian, et al. 2012). The study has also reported that the incidental ingestion of soil was found to present the highest risk among the various pathways considered.

• Further, when class B bio-solid is applied to private land, USEPA guidelines recommend that entry to this land be restricted for 30 days.

Scope

Only one pathogen, i. e. adenovirus

The exposure to pathogens through inadvertent ingestion of soil

Exposure time up to 31 days

• This study also addresses the effect of inactivation of pathogens (decay rate) in the environment. Inactivation of adenovirus under three different temperatures, 4oC, 20oC and 35oC is considered in the analysis.

DOSE RESPONSE

Risk of infection (Riskinf) depends on exposed dose (Doseexp), pathogen type (Pathogen), and pathogen-specific dose-response model (ModelD-R).

Different dose-response models exist for different pathogen-exposure route pairs.

In general, two dose-response models: “Exponential model” and “Beta-Poisson model” have been extensively used to calculate the risk of infection from microbial exposure

The exponential model has only one parameter (i.e., r : fraction of the ingested microorganisms that survive to initiate infections or host-microorganisms interaction probability.

The Beta-Poisson model has two parameters (i.e., a and b), which can be related to the median effective dose (Doseexp, 50%, i.e., a dose required to infect 50% of the population).

For adenovirus the exponential model has been proved to be applicable. The equation is as follows.

𝑅𝑖𝑠𝑘𝑖𝑛𝑓 ,𝑒𝑥𝑝𝑡𝑙=1−𝑒(−𝑟𝑥𝐷𝑜𝑠𝑒𝑒𝑥𝑝)

Adenovirus• Non-enveloped DNA virus

• 70-90 nm in size

• Linear ds DNA genome with core proteins

• Icosahedral capsid with 252 capsomeres

• (12 pentons at vertices and 240 hexons)

• Subgroups- 6 subgroups (A-F), based on

hemagglutination

• Serotypes-57 (human)

• Common serotypes:- 1-8, 11, 21, 35, 37, 40

• Enteric Adenoviruses belong to subgroup F

TRANSMISSION• Droplets

• Fecal-oral route

• Direct and through poorly chlorinated water

• Fomites

• close personal contact, ( touching or shaking hands)

• coughing and sneezing

• touching an object or surface with adenoviruses on it then touching your mouth, nose, or eyes before washing your hands

• Some adenoviruses can spread through an infected person’s stool, example,( during diaper changing can also spread through the water, such as swimming pools),

• Incubation period- 2-14 days

• Infective period continues for weeks

SIGNS AND SYMTOMS• Sore throat (pharyngitis)

• Bronchitis

• Pneumonia

• Diarrhea

• Pink eye (conjunctivitis) Keratoconjunctivitis

• Fever

• Bladder inflammation or infection (cystitis)

• Inflammation of stomach and intestines (gastroenteritis)

• pharyngoconjunctival fever, often seen in small outbreaks among school-age kids,

PATHOGENISIS

• replication in nucleus; very host dependent

• Viremia

• persistence in kidneys; reactivation with immune compromise

• inapparent infection; hemorrhagic cystitis;

• Persistent infection occurs in the tonsils.

TREATMENT• Most adenovirus infections are mild and typically require only treatment of symptoms.

• There is no specific therapy for adenoviruses.

• Bed rest and isolation to prevent spread of infection.

• Drinking plenty of water and clear fluids. This prevents dehydration.

• Pracetamol/Acetaminophen or Ibuprofen is most commonly used.

• Humidifiers may be prescribed to ease a sore throat and blocked nose.

• Lozenges and cough drops may be taken to ease the throat and cough..

TREATMENT Contd..• In those with conjunctivitis eye drops with

antibiotics and ointments are advised.

• Complications such as pneumonia need to be managed in the hospital after admission.

• Those with meningitis also need to be admitted to the hospital and managed with antibiotics, oxygen, intravenous fluids etc

• Cidofovir is an antiviral agent that has been used to treat severe adenovirus infections in people with suppressed or low immune systems

VACCINE

• Oral live attenuated vaccine

• Strains 4, 7

• Used in military recruits

• Manufacture of vaccine was halted in 1996

PREVENTION

• washing your hands often with soap and water

• covering your mouth and nose when coughing or sneezing

• not touching your eyes, nose, or mouth

• avoiding close contact with people who are sick

• staying home when you are sick

• Frequent hand washing is especially important in childcare settings.

Exposure Assessment- Assumptions

Item/Parameter Details/Magnitude Remarks/Comments

Pathogen Adenovirus Rated significant by Gurian, et al. 2012

Exposure route Direct, inadvertent ingestion of soil

Rated significant by Gurian, et al. 2012

Receptors 1. Adult conducting moderate outdoor activity (Incidental exposure)

2. Adult conducting rigorous activity (Occupational exposure)

USEPA 1997

Ingested quantity of soil 1. Incidental exposure- 0.05g2. Occupational exposure-

0.48g

USEPA 1997

Number of adenovirus/g of dry biosolid

3.7 to 22.6 with an arithmetic mean value of 17.6

Pepper et al. 2010

Dilution of bio-solid in soil

1.75×10-3 Brooks, et al. 2012

Exposure Assessment- Assumptions

Item/Parameter Details/Magnitude Remarks/Comments

Exposure measured on

Day 0, Day 1, Day 7, Day 14, Day 30 and Day 31 after biosolid application

30 days is the limit of restriction recommended by USEPA

Temperatures considered

4oC, 20oC and 35o C

Soil inactivation rates of adenovirus were available for these temperatures

Log10 inactivation

rate of adenovirus in soil (day-1)

For days 0 and 1: -0.0719 (4oC), -0.1164 (20oC), -0.8880 (35oC)For days 7, 14, 30 and 31: -0.0606 (4oC), -0.1220 (20oC), -0.7737 (35oC)

Davies, et al. 2006At days 0 and 1,the soil assumed wet and dry in other days

Dose-response parameter, r (day‑1)

0.42 Crabtree et al.1997

Organisms ingested

Risk Characterization

Incidental Exposure Occupational ExposureDay Temp Average Lower Upper Average Lower Upper

04 6.4659E-04 1.3597E-04 8.3021E-04 6.1900E-03 1.3045E-03 7.9416E-0320 6.4659E-04 1.3597E-04 8.3021E-04 6.1900E-03 1.3045E-03 7.9416E-0335 6.4659E-04 1.3597E-04 8.3021E-04 6.1900E-03 1.3045E-03 7.9416E-03




304 9.8349E-06 2.0676E-06 1.2629E-05 9.4411E-05 1.9848E-05 1.2123E-0420 1.4150E-07 2.9748E-08 1.8170E-07 1.3584E-06 2.8558E-07 1.7444E-0635 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00

314 8.5540E-06 1.7983E-06 1.0984E-05 8.2115E-05 1.7263E-05 1.0544E-0420 1.0685E-07 2.2463E-08 1.3720E-07 1.0257E-06 2.1564E-07 1.3172E-0635 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00

•restriction recommended by USEPA regarding the entry to land applied with biosolids is reasonable in limiting the risk from adenovirus infection

•Some of the earlier studies have not considered the dilution of pathogens in soil


•Strictly follow the USEPA regulations regarding entry

•In case inadvertent contact with soil is suspected▫washing hands with soap and water▫not touching the eyes, nose, or mouth


Thank You

Important References

• Brooks, J.P., M.R. McLaughlin, C.P. Gerba, and I.L. Pepper. " Land application of manure and class B biosolids: An occupational and public quantitative microbial risk assessment." J. Environental Quality 41 (2012): 2009–2023.

• Crabtree, K.D., C.P. Gerba, J.B. Rose, and C.N. Haas. "Waterborne adenovirus: A risk assessment." Water Sci. Technol. 35 (1997): 1–6.

• Davies, C.M., et al. "Soil inactivation of DNA viruses in septic seepage." J. Appl. Microbiol. 100 (2006): 365–374.

• Enriquez, C. E., and C. J. Hurst. "Survival of the Enteric Adenovirus-40 and Adenovirus-41 in Tap, Sea, and Waste-water." Water Research 29, no. 11 (1995): 2548-2553.

• Gurian, P.L., et al. Site Specific Risk Assessment Tools for Land-Applied Biosolids. Alexandria: Water Environment Research Foundation, 2012.

revised biosolids ppt

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