Soil hygieneBasics, sources of pollution, waste management, prevention of soil

pollution

Definition of soil hygiene

• Soil hygiene focuses on natural and anthropogenic pollutants (from water and through air precipitation, chemicals, waste, sewage) present in soil, affecting human health.

Basics of soil hygieneStructure, biomantle, indicators

Structure and composition of soil

• The soil is the superficial layer of Earth’s solid crust and also part of the biosphere.

• Soil consists of solid particles packed together in a porous structure.

• In the pores air, vapor, water or smaller particles may appear, and this is also where the special microflora of the soil resides.

Soil biomantle

• The soil biomantle consists of:

• Animals, soil mesofauna and microorganisms that mix soil as they form burrows and pores, allowing moisture and gases to move about. In the same way, plant roots open channels in soils as well.

• Plants with deep taproots can penetrate many meters through the different layers to absorb nutrients. Plants with fibrous roots that spread out near the soil surface have roots that are easily decomposed, adding organic matter to the soil.

• Microorganisms, including fungi and bacteria, affect chemical exchanges between roots and soil and act as a reservoir of nutrients.

• Humans influence soil formation by removing the vegetation cover, which in turn leads to erosion.

Cleanness of soil

Coli-tytre Perfringens-

tytre

Number

of

helminthes

eggs in 1 kg

Sanitary

index*

Flies

chrysalis in

0.25 m2

Clean >1.0 >0.1 0 0.98-1.0 0

Low pollution 1.0-0.01 0.1-0.001 10 0.85-0.98 1-9

Polluted 0.01-0.001 0.001-0.0001 10-100 0.7-0.85 10-25

Heavily polluted <0.001 <0.0001 >100 <0.7 >25

Sources of soil pollutionInorganic, organic and radioactive pollution, soil-borne human pathogens

Sources of pollution

• Inorganic: industry, traffic (heavy metals)

• Organic: natural (animal corpses, dead plants), human (oil, detergents, pesticides, etc.)

• Radioactive

• Microbial agents: fungi, helminths, bacteria, spores, protozoans

Most important soil contaminants

• Inorganic pollutants

1. Nitrates and nitrites

2. Heavy metals

3. Arsenic

• Organic pollutants

6. Pesticides

7. PAH

8. Soil-borne pathogens

• Radioactive pollution

1. Nitrates and nitrites

• Nitrates and nitrites are not retained in soil and quickly partition to any water phase or absorbed by the crop, and can appear in food inturn.

• Nitrates have been detected in breast milk, and concentrations increased with increasing consumption of nitrates by the mother.

• As seen earlier, the most sensitive health effect endpoint for nitrate exposure is methemoglobinemia in infants, also called “blue baby syndrome.”

Nitrites and nitrates in vegetables

• Vegetables grown in the fall at high latitudes in the presence of nitrate fertilizer, low air temperatures, frost events and low light intensity, will generally have increased levels of nitrates.

• Fruits’ nitrate content was lower than vegetables nitrate

Nitrites, nitrates and cancer

• The U.S. EPA concluded that there was conflicting evidence in the literature as to whether exposures to nitrate or nitrites are associated with cancer in adults and in children.

• Exposures to nitrates or nitrites during pregnancy, and possible associations with incidence of cancer in children, have been studied.

• Two studies reported that increased risk of brain tumors in children was significantly associated with increased maternal consumption of increasing amounts of cured meats (containing nitrates and nitrites) during pregnancy.

2. Heavy metals

• The most common problem causing cationic metals are mercury, cadmium, lead.

• One of the most common anionic compounds is arsenic.

• Their effects weredescribed earlier.

3. Arsenic

• Arsenic is a naturally occurring element in soil.

• As seen earlier, arsenic can reach high levels in potable water in certain parts of the world.

• All plants pick up arsenic, especially if grown in soil containing high amounts of arsenic.

• Concentrations in leaves of plants are much higher than in grains of plants.

• However, organic arsenic is less dangerous tha inorganic arsenic found in water.

• No need to change diet because of arsenic.

Arsenic level in common foods

4. Pesticides

• Any substance or mixture of substances intended for preventing, destroying, repelling, or mitigating any insects, rodents, nematodes, fungi, or weeds, or any other forms of life declared to be pests; any substance or mixture of substances intended for use as a plant regulator, defoliant, or desiccant.”

/Federal Insecticide, Fungicide, and Rodenticide Act (US EPA, 1947)/

Global pesticide production

Pesticide movement

• Air (drift)• particles, droplets

• vapors (fumigants, non fumigants)

• Water• drift, leaching, runoff

• spills, leaks

• improper disposal

• too much water – rain, irrigation, etc.

• On plants, animals, objects• contaminated clothing

• high residues, over tolerances

Pesticides detected in humans

• Pesticides or metabolites detected in general population between 1999 and 2000

• Organophosphates

• Organochlorines

• Carbamates

• Herbicides

• Pest Repellents & Disinfectants

Unwanted effects of pesticides

1. Immediate or direct injury to nontargetorganisms includingbees, humans.

2. Long-term consequences of environmental pollution (POPs, seelater)

Persistent organic pollutants

• Persistent organic pollutants (POPs) are toxic chemicals that adversely affect human health and the environment around the world.

• Because they can be transported by wind and water, most POPs generated in one country can and do affect people and wildlife far from where they are used and released.

• They persist for long periods of time in the environment and can accumulate and pass from one species to the next through the food chain.

Sources of POPs

• Intentionally produced chemicals currently or once used in agriculture, disease control, manufacturing, or industrial processes. Examples include PCBs (e.g., in electrical transformers and large capacitors, as hydraulic and heat exchange fluids, and as additives to paints and lubricants) and DDT, which is still used to control mosquitoes that carry malaria in some parts of the world.

• Unintentionally produced chemicals, such as dioxins, that result from some industrial processes and from combustion (for example, municipal and medical waste incineration and backyard burning of trash).

Effects of POPs

• In people reproductive, developmental, behavioral, neurologic, endocrine, and immunologic adverse health effects have been linked to POPs.

• People are mainly exposed to POPs through contaminated foods.

• Less common exposure routes include drinking contaminated water and direct contact with the chemicals.

The Dirty DozenPOP Global Historical Use/Source

Aldrin, Dieldrin Insecticides used on crops such as corn and cotton; also used for termite control.

Chlordane Insecticide used on crops, including vegetables, small grains, potatoes, sugarcane, sugar beets, fruits,

nuts, citrus, and cotton. Used on home lawn and garden pests. Also used extensively to control termites.

DDT Insecticide used on agricultural crops, primarily cotton, and insects that carry diseases such as malaria

and typhus.

Endrin Insecticide used on crops such as cotton and grains; also used to control rodents.

Mirex Insecticide used to combat fire ants, termites, and mealybugs. Also used as a fire retardant in plastics,

rubber, and electrical products.

Heptachlor Insecticide used primarily against soil insects and termites. Also used against some crop pests and to

combat malaria.

Hexachlorobenzene Fungicide used for seed treatment. Also an industrial chemical used to make fireworks, ammunition,

synthetic rubber, and other substances.

Also unintentionally produced during combustion and the manufacture of certain chemicals. Also an

impurity in certain pesticides.

PCBs Used for a variety of industrial processes and purposes, including in electrical transformers and

capacitors, as heat exchange fluids, as paint additives, in carbonless copy paper, and in plastics.

Also unintentionally produced during combustion.

Toxaphene Insecticide used to control pests on crops and livestock, and to kill unwanted fish in lakes.

Dioxins, Furans Unintentionally produced during most forms of combustion, including burning of municipal and medical

wastes, backyard burning of trash, and industrial processes. Also can be found as trace contaminants in

certain herbicides, wood preservatives, and in PCB mixtures.

DDT

• DDT is likely one of the most famous and controversial pesticides ever made.

• An estimated 4 billion pounds of this inexpensive and historically effective chemical have been produced and applied worldwide since 1940.

• In the United States, DDT was used extensively on agricultural crops, particularly cotton, from 1945 to 1972.

• DDT was also used to protect soldiers from insect-borne diseases such as malaria and typhus during World War II, and it remains a valuable public health tool in parts of the tropics.

Effects of DDT

• The heavy use of this highly persistent chemical, however, led to widespread environmental contamination and the accumulation of DDT in humans and wildlife

• Scientific laboratory and field data have now confirmed research from the 1960s that suggested, among other effects, that the high levels of DDE (a metabolite of DDT) in certain birds caused their eggshells to thin so dramatically they could not produce live offspring.

5. Polycyclic Aromatic Hydrocarbons (PAHs)

• PAHs are a concern because they are persistent and some are volatile

• PAHs are used to make dyes, plastics, pesticides and sometimes medicine.

• Human is exposed to PAHs by air, food or drinks.

• A number of PAHs have caused tumors in laboratory animals that were exposed to PAHs through their food, from breathing contaminated air, and when it was applied to their skin.

• When pregnant mice ate high doses of a PAH (benzo(a)pyrene) they experienced reproductive problems. In addition, the offspring of the pregnant mice showed birth defects and a decrease in their body weight. Other effects include damage to the skin, body fluids, and the immune system.

• However, these effects have not been seen in humans.

6. Soil-borne human pathogens I.

• Permanent: Organisms spend their entire lifecycle in the soil.

• Clostridium botulinum

• C. tetani

• Burkholderia pseudomallei

• Listeria monocytogenes

• Coccidioides

• Histoplasma capsulatum

• Periodic: Organisms require soil environment as a part of their lifecycle.

• Bacillus anthracis spores

• Rickettsia rickettsii in tick eggs

• Helminth eggs (Ancylostoma duodenale, Necator americanus)

Soil-borne human pathogens II.

• Transient: Organisms may occur naturally in soil, but do not require soil to complete their lifecycle.• G. lamblia cysts

• Hantavirus

• Leptospira

• Coxiella burnetii spores

• Incidental: Organisms introduced to the soil environment through anthropogenic activities (Survival can range from hours to years.)• Poliovirus

• Coxsackie A and –B

• Hepatitis A

Grade of the soil’s microbiological contamination

• The contamination is usually measured by the number of coliform bacteria in 1 g of soil. Typical genera include:

• Citrobacter,

• Enterobacter

• Hafnia

• Klebsiella

• Serratia

• Fecal coliform: Escherichia

• Helminth contamination is expressed by the number of helminth eggs in 1 kg of soil.

Routes of transmission

• Ingestion (most common route): Direct ingestion of contaminated soil or of food/objects that came in contact with contaminated soil.

• Inhalation

• Dermal penetration: Microbes rarely penetrate intact skin. For instance, Strongyloides (nematode) can penetrate through healthy skin. On the other hand, C. tetani usually enters through wounds.

Soil-transmitted helminthiasis

• 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 areas where sanitation is poor.

• Approximately two billion people are infected with soil-transmitted helminths worldwide.

• Infected children are physically, nutritionally and cognitively impaired.

• Control is based on: • periodical deworming to eliminate infecting worms

• health education to prevent reinfection

• improved sanitation to reduce soil contamination with infective eggs.

• Safe and effective medicines are available to control infection.

Risk groups

• The strategy for control of soil-transmitted helminth infections is to control morbidity through the periodic treatment of at-risk people living in endemic areas. People at risk are: • preschool children;

• school-age children;

• women of childbearing age (including pregnant women in the second and third trimesters and breastfeeding women); and

• adults in certain high-risk occupations, such as tea-pickers or miners.

• 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 helminthinfections in the community is over 50%.

Treating STH and global target

• The recommended medicines – albendazole (400 mg) and mebendazole (500 mg) – are effective, inexpensive and easy to administer by non-medical personnel (e.g. teachers). They have been through extensive safety testing and have been used in millions of people with few and minor side-effects.

• 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).

Toxoplasmosis and pregnency

• Toxoplasmosis is a disease that results from infection with the Toxoplasma gondii parasite, one of the world's most common parasites.

• Toxoplasmosis may cause flu-like symptoms in some people, but most people affected never develop signs and symptoms.

• For infants born to infected mothers, toxoplasmosis can cause extremely serious complications.

• Many early infections end in stillbirth or miscarriage. Children who survive are likely to be born with serious problems, such as:• Seizures• An enlarged liver and spleen• Yellowing of the skin and whites of the eyes (jaundice)• Severe eye infections

Prevention and treatment of infant toxoplasmosis

• The diagnosis of toxoplasmosis is typically made by serologic testing. A test that measures immunoglobulin G (IgG) is used to determine if a person has been infected.

• If it is necessary to try to estimate the time of infection, which is of particular importance for pregnant women, a test which measures immunoglobulin M (IgM) is also used along with other tests such as an avidity test.

• If mother is infected during pregnancy, medication is available.• If baby isn't affected, then usually with spiramycin.

• If affected, then pyrimethamine and sulfadiazine (but only in extreme circumstances and after the 16th week of pregnancy)

Other precautions I.

• Cook food to safe temperatures. A food thermometer should be used to measure the internal temperature of cooked meat. Do not sample meat until it is cooked.

• Avoid drinking untreated drinking water.

• Wear gloves when gardening and during any contact with soil or sand because it might be contaminated with cat feces that contain Toxoplasma. Wash hands with soap and warm water after gardening or contact with soil or sand.

• Teach children the importance of washing hands to prevent infection.

• Keep outdoor sandboxes covered.

Other precautions I.

• Feed cats only canned or dried commercial food or well-cooked table food, not raw or undercooked meats.

• Change the litter box daily if you own a cat. The Toxoplasma parasite does not become infectious until 1 to 5 days after it is shed in a cat's feces.

• If you are pregnant or immunocompromised: 1. Avoid changing cat litter if possible. If no one else can

perform the task, wear disposable gloves and wash your hands with soap and warm water afterwards.

2. Keep cats indoors.3. Do not adopt or handle stray cats, especially kittens. Do

not get a new cat while you are pregnant.

Other important soil-borne pathogens

• Clostridium Tetani

• Clostridium Botulinum

Radioactive pollution

• The sources of radiation can be natural (e.g. radon, see later) and anthropogenic.

• Man-made radiation pollution involve any process that emanates radiation in the environment.

• Sources can be:• Nuclear explosions and detonations of

nuclear weapons• Nuclear waste handling and disposal of

nuclear power plants• Mining of radioactive ores (such as

uranium ores)• Nuclear accidents

Waste managementDomestic, industrial and health care waste

Definition of waste

• Wastes are materials that are not prime products (that is produced for the market) for which the initial user has no further use in terms of his/her own purposes of production, transformation or consumption, and of which he/she wants to dispose.

Sources of waste

• Municipal solid and liquid waste • Trash/garbage from streets

and households, and sewage

• Agricultural and industrial non-hazardous waste

• Hazardous waste: chemical, mechanical & food industries, health care services

The amount of municipal solid waste generated per capita in kilograms

Average household waste composition

• At least 70% of municipal waste could be recycled!

Steps of waste management

Final steps of waste management

• Recycling,

• Incineration and

• Land filling.

Health care waste management

• Medical wastes are separated and disposed in a pit or incinerator with a deep ash pit, usually within the boundaries of each health facility.

• Ideally there are no contaminated or dangerous medical wastes (needles, glass, dressings, drugs, etc.) at any time in living areas or public spaces.

• Final disposal of solid waste is carried out in such a place and in such a way as to avoid creating health and environmental problems for the local and affected populations.

Categories of health care waste I.

• Infectious waste: suspected to contain pathogens (e.g. laboratory cultures; waste from isolation wards; tissues (swabs), materials, or equipment that have been in contact with infected patients; excreta)

• Pathological waste: human tissues or fluids (e.g. body parts; blood and other body fluids; fetuses)

• Sharps: sharp waste (e.g. needles; infusion sets; scalpels; knives; blades; broken glass)

• Pharmaceutical waste: waste containing pharmaceuticals (e.g. pharmaceuticals that are expired or no longer needed; items, bottles or boxes, contaminated by or containing pharmaceuticals)

• Genotoxic waste: waste containing substances with genotoxic properties (e.g. waste containing cytostatic drugs)

Categories of health care waste II.

• Chemical waste: waste containing chemical substances (e.g. laboratory reagents; film developer; disinfectants that are expired or no longer needed; solvents)

• Wastes with high content of heavy metals (e.g. batteries, broken thermometers; blood-pressure gauges)

• Pressurized containers (e.g. gas cylinders; gas cartridges; aerosol cans)

• Radioactive waste: waste containing radioactive substances (e.g. unused liquids from radiotherapy or laboratory research; contaminated glassware, packages, or absorbent paper; urine and excreta from patients treated or tested with unsealed radionuclides)

Disposal of hospitalwaste

Factors influencing the amount of health carewaste

• The amount of health care waste depends on many factors as forexample:

• national income level (high-middle-low income countries)

• geographic region

• type of health care facility

National income level and annual waste generation (kg/capita)

• High-income countries

• all health-care waste: 1.1–12.0

• hazardous health-care waste: 0.4–5.5

• Middle-income countries

• all health-care waste 0.8–6.0

• hazardous health-care waste 0.3–0.4

• Low-income countries

• all health-care waste 0.5–3.0

Geographic region and daily waste generation (kg/hospital bed)

• North America 7–10

• Western Europe 3–6

• Latin America 3

• Eastern Europe 1.4–2

• Eastern Mediterranean 1.3–3

• Eastern Asia:

• high-income countries 2.5–4

• middle-income countries 1.8–2.2

Type of health care facility: daily waste generation (kg/patients)

• University hospital 4.1–8.7

• General hospital 2.1–4.2

• District hospital 0.5–1.8

• Primary health-care center 0.05–0.2

Prevention of soil pollutionDecrease amount of waste, agricultural alternatives, prevention of erosion soilmanagement

Decreasing the amount of waste by recycling

• Recycling conserves resources

• Recycling saves energy

• Recycling helps protect the environment while reducing the need for extracting, refining and processing raw materials all of which create substantial air and water pollution.

• Recycling reduces landfill by the amount of remaining rubbish sent to landfill sites.

Seeking for agricultural alternatives

• Industrialized agriculture is no longer sustainable.

• Effects of industrialized agriculture:

• Declining biodiversity

• Exhaustion of soil

• Soil pollution

• Contamination of food

• Decreasing nutritional value of foods.

Decreasing biodiversity

• From the total of 300 000 plant species 3000 can be used for nutritional purpose.

• Yet humanity grows only 200 of these species.

• Furthermore only 20 species are used to provide food for 80% of total population.

• In the past century we lost 75% of our agricultural plants.

• The remaining 25% are in danger.

The Great Famine

• The Great Famine was a period of mass starvation, disease and emigration in Ireland between 1845 and 1852.

• It is sometimes referred to, mostly outside Ireland, as the Irish Potato Famine because about two-fifths of the population was solely reliant on this cheap crop.

• The proximate cause of famine was a potato disease commonly known as potato blight.

• A disproportionate share of the potatoes grown in Ireland were of a single variety, the Irish Lumper.

Dangers of GMO plants

• Long-term effects are unknown.

• Once grown in fields it is impossible to contain them.

• Gene exchange between plants cannot be prevented.

• Due to selectional advantage, biodiversity will decrease furthermore.

• GMO plants may have adverse effect on naturally occurring organisms in the environment.

Characteristics of modern agriculture

• Farming depends greatly on unsustainable energy resources and artificial fertilizers.

• The amount of food produced each year would be enough to feed 12-14 billion people.

• Still approximately 2 billion people suffer from undernutrition/famine.

Effects of industrialized agriculture

• Due to industrialized agriculture the nutritional value of foods is continuously decreasing.

• According to data from the UK between 1940 and 1991:• Potato lost 47% of its copper, 45% of its iron, 75% of its

magnesium.

• Broccoli’s calcium content decreased by 75%

• According to Canadian data between 1955 and 1999 potatoes lost 57% of their vitamin A and C content.

• German data revealed the same trends.

The decreases of nutritional value expressed in percentage according to European data

Tomatoes Wheat

A-vitamin 92% -

C-vitamin 96% O%

E-vitamin 55% 86%

B1-12 vitaminok 8-88% 16-49%

Na 96% 94%

Mg 79% 28%

Ca 24% 23%

Fe 83% 67%

Cu 2% 29%

Effects of industrialized livestock farming

• According to data milk’s:

• calcium content decreased by 20%,

• its magnesium content decrease by 21%,

• its iron content decreased by 60%.

• As it is processed into cheese, it loses 70% of its iron and magnesium content.

Replacing pesticides

• Certain predators, parasites, bees and other microorganisms could act as natural barriers and protect our crops from harm.

• 90% of harm done by insects could be prevented by using natural predators.

• The use of pesticides to replace these natural defenses costs us 54 billion dollars eachyear.

Farming of the future

• One of WHO’s main goals is to reform modern agriculture.

• Organic farming relies on natural and environment-friendly techniques such as crop rotation, green manure, compost, and biological pest control.

• Organized small and medium farmers, fully including women farmers, should be a primary focus of investment – recognizing that private enterprise will play a significant role in many solutions

Prevention of soil erosion

• Unsustainable agricultural practices are the single greatest contributor to the global increase in erosion rates.

• Impacts include decreases in agricultural productivity and (on natural landscapes) ecological collapse, both because of loss of the nutrient-rich upper soil layers. In some cases, the eventual end result is desertification.

• The problem has been exacerbated in modern times, due to mechanized agricultural equipment that allows for deep plowing, which severely increases the amount of soil that is available for transport by water erosion.

• Others include mono-cropping, farming on steep slopes, pesticide and chemical fertilizer usage (which kill organisms that bind soil together), deforestation.

• The most effective known method for erosion prevention is to increase vegetative cover on the land.

• Terracing is an extremely effective means of erosion control, which has been practiced for thousands of years by people all over the world

Soil management in case of pollution

• Increasing the soil pH to 6.5 or higher• Cationic metals are more soluble at lower pH levels, so increasing the pH makes

them less available to plants and therefore less likely to be incorporated in their tissues and ingested by humans

• Draining wet soils• Drainage improves soil aeration and will allow metals to oxidize, making them less

soluble.

• Applying phosphates• Heavy phosphate applications reduce the availability of cationic metals, but have the

opposite effect on anionic compounds like arsenic.

• Phytoremediation• Phytoremediation is a general term for using plants to remove, degrade, or contain

soil pollutants such as heavy metals, pesticides, solvents, crude oil, polyaromatichydrocarbons.

Thank you for your attention!