Hygiene of soil
•Download as PPTX, PDF•
1 like•2,584 views
The lecture covered various topics related to soil including its content, properties, macronutrients, micronutrients, and role in geochemical and toxicological processes. It discussed soil contamination from various sources and soil-borne infectious and non-infectious diseases. It also summarized the virulence of some pathogenic microbes in soil, WHO strategies for controlling soil-transmitted diseases, and the epidemiological role of wastes and how long various infection agents can survive in different environments.
Recommended
More Related Content
What's hot
What's hot (20)
Similar to Hygiene of soil
Similar to Hygiene of soil (20)
More from Alok Kumar
More from Alok Kumar (20)
Recently uploaded
Recently uploaded (20)
Hygiene of soil
- 2. Content of the lecture • Soil content and its properties • Geochemical and toxicological role of soil • Soil contamination • Soil borne infectious and non-infectious diseases • Self-purification of soil • Epidemiological role of wastes • References
- 3. Soil
- 4. Soil content and its properties Soil is superficial layer of ground with 2 cm-2 m of thickness. Soil consists of mineral and organic part, humus, live organisms, air and water
- 6. Properties of soil • Air permeability – Increases biochemical oxidation processes in soil • Water permeability – Effects on formation of soil water and ground water • Water capacity – Conditions air permeability and wetness of soil and possibility of constructions of building on it • Capillarity of soil – Causes wetness of buildings
- 7. The Macronutrients of soil Element Symbol Chemical Form in Soil Calcium Ca Ca2+ Carbon C HCO3 -, CO3 2- Hydrogen H H+ Magnesium Mg Mg2+ Nitrogen N NO3 -, NH4 + Oxygen O HO- Phosphorous P H2PO4-, HPO4 2- Potassium K K+ Sodium Na Na+
- 8. The Micronutrients of soil Micronutrients are classified as "essential" and "non-essential." An essential plant nutrient is one that is required for life, whereas a non-essential plant nutrient (present in soil a very low levels) will increase crop yield. But its absence will not cause the organism to die.
- 9. The essential micronutrients • Provision of our body by microelements is conditioned by their contents in soil, water and food. We receive the most of microelements with vegetable food. • 99% of our body is 12 chemical elements included in the first 20 elements of the periodical table. • 9 microelements, such Fe, I, Cu, Cr, Co, Mo, Mg, Zn, Se, are essential or vitally needed. Surplus and insufficiency of them can cause diseases. Less essential microelements are F, Ni, V, As, Si, Li, B and Br. In the group of toxic elements Al, Cd, Pb, Hg, Be, Ba, V and Tl are included. • Indifferent and inert elements are Tn, Pl, Au and Ag used often as surgical implants. Some elements have therapeutic effect. Hg substances are used in treatment against parasites, Li – maniac depression.
- 10. Biogeoendemic diseases Goitre, fluorosis, caries, molybdenosis, Hondro- and osteodistrophia (Sr), Encephalitis (Pl), Selenium toxicosis
- 11. Geochemical and toxicological role of soil 9 essential microelements: Fe, I, Cu, Cr, Co, Mo, Mg, Zn, Se Less essential microelements: F, Ni, V, As, Si, Li, B and Br Toxic elements: Al, Cd, Pb, Hg, Be, Ba, V and Tl Indifferent and inert elements: Tn, Pl, Au and Ag Surplus and insufficiency of them can cause diseases
- 12. Molybdenum • Antagonist of Cu in biological tissues • Activates a few of enzymes • 15 enzymes (aldehydroxidase, xanthinoxidase & sulphitoxidase), consist Mo • Xanthinoxidase catalyzes formation of urine acid (defect in Purina exchange → Ksantinuria, Xanthin stones in renal canals) • Sulphitoxidase makes sulphates from sulphites in our body (Defect in sulphiteoxidase → brain anomaly, idiotism, ectopia of the eye crystalline lens, increased excretion of sulphites, tiosulphates by urine) • Surplus of Mo → Mo-gout, accumulation of urine acid in
- 13. Boron Regulates activity of parathyroid hormone, and therefore, Ca, P and cholecalciferoli exchange. In our body, there is ≈ 20 mg of B Surplus of Boron in soil → Boron enteritis, increase of anaemia and respiratory diseases Boron acid is cumulated in our brain, liver and adipose tissue (acute boron intoxication → involvement CNS)
- 14. Bromine Distributed in all tissues equally, but mostly it is concentrated in thyroid and kidneys Selectively influences on braking processes in neurones of the cerebral cortex Increase in Br intake of chlorides → increase of bromine excretion Chronic increased intake of Br → allergic or measles-like rash, brown colouration of mouth mucous membrane, conjunctivitis and bronchospasms
- 15. Soil contamination Technogenic biogeoendemic provinces High concentration of Pb, As, F, Hg, Cd, Mn, Ni and other elements, benz(a)pyren, pesticides, etc If transport load of the road is up to 10 000 cars per day, concentration of iron is 1000 mg/kg in superficial soil layer, Zn – 20 mg/kg, Pb - 10 mg/kg and 0.2 mg/kg of Cd They present real danger of direct and indirect impact on a body through food chain
- 16. Soil Pollution: The introduction of substances, biological organisms, or energy into the soil, resulting in a change of the soil quality, which is likely to affect the normal use of the soil or endangering public health and the living environment.
- 17. Soil contaminants are spilled onto the surface through many different activities. Most of these are the result of accidents involving the vehicles that are transporting waste material from the site at which it originated to the site at which it is to be disposed.
- 18. Others involve accidents involving vehicles (automobiles, trucks and airplanes) not transporting wastes, but carrying materials, including fuel, that when spilled contaminate the soil.
- 19. Still other spills are the direct action of humans pouring potentially toxic materials (solvents, paints, household cleaning agents, etc.) onto the ground surface rather than disposing these materials by more appropriate means
- 20. Agricultural practices including the use of agricultural chemicals are another primary source of pollution on or near the ground surface Most agricultural chemicals are water-soluble nitrates and phosphates that are applied to fields, lawns and gardens to stimulate the growth of crops, grass and flowers
- 21. When not used by the plants the nutrients can enter streams & lakes during the run-off or leaching events. Once in a body of water, these chemicals continue to promote the growth of plants, the resulting plant detritus is food for micro- organisms, and as the population of such organisms grows, the supply of oxygen in the water is depleted
- 22. "Biochemical Oxygen Demand", or "BOD". This means that the water is capable of supporting a large population of bacteria that will have a high demand for oxygen
- 23. Information needed to clean up materials added to soil include: • Kind of material - organic or inorganic - is the material biodegradable, is the material dangerous to animals and humans, • how much material was added to the soil, will it overload the organisms in the soil; • C:N ratio of the material, are additional nutrients needed ( N & P)
- 24. Soil Pollution • Kind of Soil - will the soil be able to handle the material before groundwater is contaminated, • Growing conditions for the soil organisms - is it too cold, too wet etc. • How long has the material been on the site - is there evidence of environmental problems, is it undergoing decomposition. • Immediate danger to people and the environment - Urgency of the situation.
- 25. Soil borne human diseases A human diseases resulting from any pathogen or parasite, transmission of which can occur from the soil, even in the absence of other infectious individuals Euedaphic pathogenic organisms (EPOs), being potential pathogens which are true soil organisms, i.e. their usual habitat is the soil Soil transmitted pathogens (STPs) are organisms which, while they may be able to survive in soil for extended periods of time, are not true soil organisms, but rather are obligate pathogens who must infect a host in order to complete their life cycles
- 26. Soil borne infectious diseases Euedaphic pathogenic organisms Euedaphic pathogenic organisms Actinomycetoma: (e.g. Actinomyces israelii Aspergillosis: Aspergillus sp. Anthrax: Bacillus anthracis Blastomycosis: e.g. Blastomyces dermatitidis Botulism: Clostridium botulinium Coccidioidomycosis: e.g. Coccidiodes immitis Campylobacteriosis: e.g. Campylobacter jejuni Histoplasmosis: Histoplasma capsulatum Leptospirosis: e.g. Leptospira interrogans Sporotrichosis: Sporothrix schenckii Listeriosis: Listeria monocytogenes Mucormycosis: e.g. Rhizopus sp. Tetanus: Clostridium tetani Mycetoma: e.g Nocardia sp. Tularemia: Francisella tularensis Strongyloidiasis: e.g. Strongyloides stercoralis Gas Gangrene: Clostridium perferingens Yersiniosis: Yersinia enterocolitica
- 27. Soil Transmitted Pathogens Soil Transmitted Pathogens Poliovirus Trichinellosis: Trichinella spiralis Hantavirus Amoebiasis: Entamoeba histolytica Q Fever: Coxiella burnetii Balantidiasis Balantidium coli Lyme disease: Borrelia sp. Cryptosporidiosis: e.g Cryptosporidium parvum Ascariasis: Ascaris lumbricoides Cyclosporiasis: Cyclospora cayetanensis Hookworm: e.g. Ancylostoma duodenale Giardiasis: Giardia lambila Enterobiasis (Pinworm) Isosporiasis: Isospora belli Strongyloidiasis: e.g. Strongyloides stercoralis Toxoplasmosis: Toxoplasma gondii Trichuriasis (Whipworm): Trichuris trichiura Shigellosis: e.g. Shigella dyseneriae Pseudomonas aeruginosa Echinococcosis: e.g. Echinococcus multicularis Eschericia coli, Salmonellosis: e.g. Salmonella enterica
- 28. Virulence of some pathogenic microbes Bacteria Duration of preservation, months Average Maximal Salmonella Typhi 0.5 12 Shigella Sonne 1 2 Vibrio Cholera 0.5 4 Mycobacterium tuberculosis 3 7 Brucellas 0.5 2 Yersinia pestis 0.1 1 Francisella tularensis 0.5 2.5
- 29. Soil-transmitted helminth infections Soil-transmitted helminth infections are caused by different species of parasitic worms. They are transmitted by eggs present in human faeces, which contaminate the soil in area with poor sanitation Approximately 2 billion people are infected with soil- transmitted helminths worldwide Infected children are physically, nutritionally & cognitively impaired The main species that infect people are the roundworm (Ascaris lumbricoides), the whipworm (Trichuris trichiura) and hookworms (Necator americanus and Ancylostoma duodnale)
- 30. Soil-transmitted helminth infections Control is based on: periodical deworming to eliminate infecting worms health education to prevent re-infection improved sanitation to reduce soil contamination with infective eggs Safe and effective medicines are available to control infection
- 31. WHO strategy for control of soil- transmitted diseases WHO recommends periodic medicinal treatment (deworming) without previous individual diagnosis to all at-risk people living in endemic areas. Treatment should be given once a year when the prevalence of soil- transmitted helminth infections in the community is over 20%, and twice a year when the prevalence of soil-transmitted helminth infections in the community is over 50%.
- 32. Global target The global target is to eliminate morbidity due to soil-transmitted helminthiases in children by 2020. This will be obtained by regularly treating at least 75% of the children in endemic areas (an estimated 873 million).
- 33. Other non-infectious soil associated diseases • Silicosis • Geophagia (pica associations)
- 34. Bioremediation of soil Organic substances Filtration of bacteria, viruses & helmints’ eggs Decrease/elimination of smell, stink, toxicity, etc Inorganic substances Restored Health Status of Soil
- 35. Conditions that favor Bioremediation Temperature favorable for organisms Water available (near field capacity) Nutrients (N, P, K) in adequate supply C:N ratio of material < 30:1 Material added is similar to naturally occurring organic material Oxygen in sufficient quantity
- 36. Sanitary evaluation of soil Rate of danger Soil characteri stics Number of larvae per 25 m2 of soil Number of helmints’ eggs Titre of E. Coli Titre of Cl. perfringen s Sanitary index (Khlebnik ov) Safe Pure 0 0 > 1.0 > 0.1 0.98-1.0 Relatively safe Rather contamin ated 1-10 < 10 1.0-0.01 0.1-0.001 0.85-0.98 Dangerou s Contamin ated 10-100 11-100 0.01-0.001 < 0.001 0.7-0.85 Extremely dangerous Extremely contamin ated > 100 > 100 < 0.001 < 0.0001 < 0.7
- 37. Epidemiological role of wastes Infection agent Duration, days In excrements In sewage In cesspool In kitchen garbage In room dust Vibrio cholera 210 12 15 - - Salmonella typhi 100 6 150 4 42 Salmonella paratyphi - - - 24 107 Shigella Sonne - - - 24 107 Bacillum Antracis - - - - 80 Mycobacterium tuberculosis - - - - 200
- 38. Reference • S. Jeffery, W.H. van der Putten. Soil Borne Diseases of Humans (2011). Luxembourg: Publications Office of the European Union. doi:10.2788/37199 • Communicable diseases. Control of schistosomiasis and soil-transmitted helminth infections. WHO 54th WHA. 30/03/2001 • Baumgardner DJ. Soil-Related Bacterial and Fungal Infections. J Am Board Fam Med. 2012;25(5):734-744 • Park’s Textbook of Preventive and Social Medicine. Chapter 13
Editor's Notes
- Soil is a part of our ecological system and human environment. Soil plays a leading role in substance circulation in the nature. It is a great natural laboratory where many different and complex processes of synthesis and decomposition of organic and inorganic substances and photochemical reaction take place. In soil many pathogenic microbes live and die. It is one of the main transmission ways of infection and non-infection diseases. Soil may have directly and indirectly toxic, allergic, carcinogenic, and mutagenic and other effect on our body. Insufficiency and surplus of microelements can cause endemic diseases. Quality and quantity of our food is strictly connected to soil. Soil has great impact on local climate. All mentioned above shows that medical doctors should know processes taken place in soil, their features. It is to plan and take preventive measures against harmful impact of soil on people’s health.
- Chemical content of soil is very complex. 90-99% of soil is minerals (Si, Ca, Mg, Al, etc.). They are sand, clay and calcium hydrocarbonate. Almost all elements of Mendeleyev’s periodical table are presented in soil.
- Soil water has great impact on properties and content of ground and surface water. Soil air is exchanged with atmospheric air constantly. It consists 8% of CO2, 14% of O2. It can have many stink gases like NH3, H2S, HF, indole, skatole, which is toxic for us. There were some cases of death when people got contact with soil toxic gases. Air permeability of soil plays hygienic role because it increases biochemical oxidation processes in soil. Water permeability effects on formation of soil water and ground water. Water capacity of soil conditions air permeability and wetness of soil and buildings on it. Soil with big water capacity is unhealthy, wet and cold. Capillarity of soil depends on porosity of soil. Big capillarity of soil can cause wetness of buildings.
- Unequal distribution of microelements in soil around the planet causes biogeoendemic diseases. Fluorosis, caries, molybdenosis, Hondro and osteodistrophia (Sr), Encephalitis (Pl). Fluorosis: India, Kazakhstan, China, Tanzania, and Uzbekistan Insufficient Se: Finland, New Zeland, China Surplus of Se: South Dacota, Nebraska (USA), China (Hubei province). Selenium toxicosis: alopecia, inflammation of epidermis, dermatitis, teeth enamel destruction, anaemia, decrease of intake of Ca, F and nervous dysfunction. We will not talk about fluorosis, goitre, caries, ect. You know them well enough. We will talk about other diseases caused by such elements as Mo, B, Br, etc.
- Provision of our body by microelements is conditioned by their contents in soil, water and food. We receive the most of microelements with vegetable food. 99% of our body is 12 chemical elements included in the first 20 elements of the periodical table. 9 microelements, such Fe, I, Cu, Cr, Co, Mo, Mg, Zn, Se, are essential or vitally needed. Surplus and insufficiency of them can cause diseases. Less essential microelements are F, Ni, V, As, Si, Li, B and Br. In the group of toxic elements Al, Cd, Pb, Hg, Be, Ba, V and Tl are included. Indifferent and inert elements are Tn, Pl, Au and Ag used often as surgical implants. Some elements have therapeutic effect. Hg substances are used in treatment against parasites, Li – maniac depression.
- Molybdenum is antagonist of Cu in biological tissues. Mo activates a few of enzymes. Zn and H2S increase action of Mo. At present, 15 enzymes known consist Mo. Three of them are in our body: aldehydroxidase, xanthinoxidase and sulphitoxidase. Xanthinoxidase is an important enzyme in Purina exchange: it catalyzes reaction of formation of urine acid. If there is a genetic defect in ksantinoxidase and xanthine isn’t re-absorbed in renal canals there a ksantinuria will be developed lead to formation of Xanthin stones in renal canals. Sulphitoxidase makes sulphates from sulphites in our body. If there is a genetic defect in sulphite-oxidase very hard consequences happen: brain anomaly, idiotism, ectopia of the eye crystalline lens, increased excretion of sulphites, tiosulphates by urine. Surplus of Mo leads to development of the gout, accumulation of urine acid in joints. It is Mo-gout, which is revealed in Armenia.
- Physiological role of boron consists of regulation of activity of parathyroid hormone and therefore Ca, P and cholecalciferoli exchange. In our body, there is 20 mg of B. In regions with surplus of Boron in soil there boron enteritis can happen. It is met often in West Siberia, Omsk, Novosibirsk area and Altai. Except of enteritis there anaemia and respiratory diseases can be developed. Boron acid, which we use often, is cumulated in our brain, liver and adipose tissue. Acute boron intoxication, particularly by deboran, decaboran or pentaboran, can be developed. It is dangerous by involvement of CNS
- Beans are rich by bromine (peas, beans). It is distributed in all tissues equally, but mostly it is concentrated in thyroid and kidneys. Excretion of bromine from our body depends on intake of chlorides. If we have taken many chlorides with food, bromine excretion will increase. Physiological role of bromine is connected to its selective influence on braking processes in neurones of the cerebral cortex. By chronic intake of bromine people have allergic or measles-like rash, brown colouration of mouth mucous membrane, conjunctivitis and bronchospasms.
- Around industrially developed areas, technogenic biogeoendemic provinces are formed. They are characterised by high concentration of lead, arsenic, fluoride, mercury, cadmium, manganese, nickel and other elements that present real danger of direct and indirect impacts on a body. Many studies show toxic effect of soil contaminants. They can act through food chain, e.g. plants grown at polluted soil, milk and meat of animals fed by polluted forage. For example, lead of exhausted gases of cars in Bishkek contaminated soil in the city very intensive, so 30-40 times higher than limit thresholds. And in vegetables and fruits in Bishkek lead concentration is high, especially in plants growing at streets. People who use vegetables and fruits grown in Bishkek receive lead with them. Lead accumulates in the body. It can lead to development of neuralgia, cephalgia, polyneuritis, liver and skin pathologies. Crucial problem is high concentration of benz(a)pyren in soil around gas stations and along streets. It is carcinogen. To assess impact of exhausted gases of autos to soil usually ecologists carry out chemical analysis of soil samples taken at different distances up to 100 m from both sides of a road. If transport load of the road is up to 10 000 cars per day concentration of iron is 1000 mg/kg in superficial soil layer, zinc – 20 mg/kg, lead - 10 mg/kg and 0.2 mg/kg of cadmium. Pesticide use in agriculture has been increased for last decades. Hygienic importance of pesticides increases proportionally by its resistance to outer impact. Pests with high resistance accumulate in soil, water, air and vegetable and animal food, human body. The famous example is DDT – dichloro-diphenyl-trichloroethane. At present in the body of all living animal and human some concentration of DDT is present.
- Many infection agents that can be transmitted directly and indirectly to people are located in soil. Pathogenic microbes contaminate soil with excrements of animals and human, cadavers, sewage, and etc. Healthy soil is unfavourable for pathogenic non-spores bacteria. In soil contaminated with organic substances bacteria keeps its virulence for longer time. For example, bacteria of typhus-para-typhus group can be live for 400 days, Shigella dysenteriae – up to 100 days, polioviruses, ECHO, Kocksaki – 150 days, ascarid eggs – for 1 year. Duration of virulence preservation of some pathogenic microbes is presented in the table in the next slide. Infective agents can be transmitted by direct contacts with soil (especially children), by drinking contaminated water, eating contaminated vegetables and by insects, mainly flies. Soil plays big role in transmission of helmints (ascarids, etc). From the human intestine, eggs of helmints can get soil where they live the most of their life cycle and mature to invasion stage. One female ascarid can have more than 240 000 eggs. ….. Eggs can get with forage into bodies of cows and pigs. There they are changed into larva that are located mainly in muscles. These helmints’ larva infects people eating this meat. Pathogenic bacilli with spore (gas gangrene, anthrax, tetanus, actinomycosis and botulism) are permanent residents of soil. Their spores keep virulence tens of year. Rats living in soil infect water by leptosira.
- Organic substances in soil decompose to inorganic parts. They are processes of mineralization and nitrification and humification. As results of these processes, soil restore its healthy status. Organic substances, bacteria, viruses and helmints’ eggs are filtered by soil, detained there. Mechanical, physical and chemical, biological and biochemical absorbability of soil decrease or move away stink, toxicity and other negative properties of soil, and some microbes. Mainly, self-purification of soil is connected to disinfection of non-spores bacteria because of saprophytes, the sun’s UVL, mechanical factor and superficial energy of electrochemical relations in soil. Carbohydrates decompose in soil into carbon acid and water in anaerobic conditions, into fat acids and further into hydrogen, carbon acid, methane and other gases. Fats decompose in soil very slowly. They decompose into glicin and fat acids. Proteins decompose into aminoacids and then to ammonia, water and carbon acid. Ammonia is utilised by Nitrosomonas bacteria with formation of nitrites. Nitrites are oxidised into nitrates by B. Nitrobacter. Extreme contamination of soil is harmful and all useful bacteria can die. In this case, soil is not able to self-purification. It is always need to assess sanitary condition of soil. For assessment of the sanitary conditions of soil we use some indices (table 2).
- At present billions of tons of pesticides are used in the world. They decrease biological potential of soil and contaminate it by heavy metals. The main objectives of protection of soil are: Rational waste management: collection, treatment (rendering harmless) of communal sewage and waste utilization. To keep natural properties of soil. Prevention of applying toxic and carcinogenic substances into soil.
- Wastes are good environment for pathogenic agents (table 3) to grow and reservoir of more than 100 toxic substances like Hg, Cd, Pb, As, Tl, Zn and their compounds, salts, colours, pesticides, medicines, and etc.