HumBioEnvLogy: Heavy Metal Pollution, Bioaccumulation, And Effect...

HumBioEnvLogy: Heavy Metal Pollution, Bioaccumulation, And Effect...: The school of thought  that Technology brings more harm to us than good , may be as a result of our failure to apply best practices in o...

Heavy Metal Pollution, Bioaccumulation, And Effect To The Environment

The school of thought  that Technology brings more harm to us than good , may be as a result of our failure to apply best practices in our utilization of  the technological innovations in all areas of life, e. g. Exploration of both solid and liquid mineral resources, commercialisation of agriculture, construction of roads/other developmental infrastructure and their uses, industrialisation, expansion in the form of reclamation of lands, etc., in one way or the other has effect to the environment and to us that ought to manage our environment for sustenance.

The rusting of iron and steel used in construction and as ornaments, the application of inorganic fertilisers to the soil to enhance productivity for our agricultural produce, exploration of minerals that affects our atmosphere, hydrosphere and leaves soil seriously polluted, emission of carbon and other gasses which settles and react with water to become toxic to both plants and animals, and improper disposal/management of waste all are responsible for the pollution of our environment with one heavy metal or the other.

Heavy metals are members of loosely defined subset of elements that exhibit metallic properties. Lots of definitions have been proposed, some based on density (6.0g/cm³ or more (much higher than the average particle density of soils which is 2.66g/cm³)), some on atomic number or atomic weight, and some on chemical properties. These metals are alternatively called toxic metals, irrespective of their atomic mass or density.

Heavy metals include ill-defined subset of elements that exhibit metallic properties, which are transition metals, some metalloids, lanthanides, and actinides. These metals cause environmental pollution from sources such as leaded petrol, industrial effluents, and leaching of metal ions from the soil into lakes and rivers by acid rain. Other sources of heavy metal pollutants are metal mining, metal smelting, metallurgical industries, waste disposal, and corrosion of metals in use, agriculture and forestry. Heavy metals contamination affects large areas world-wide, but hot spots of pollution are locations close to the landfills, industrial sites, around large cities and in the vicinity of mining and smelting plants. This makes Agriculture within the areas to face major problems due to heavy metal transfer into crops and subsequently into the food chain.

The most important heavy metals with regard to potential hazards and occurrence in contaminated soils are:- Arsenic (As), Cadmium (Cd), Chromium (Cr), Mercury (Hg), Lead (Pb), Zinc (Zn), Copper (Cu), Selenium (Se), Nickel (Ni), Silver (Ag). Others that are less common metallic contaminants include Aluminium (Al), Caesium (Cs), Cobalt (Co), Manganese (Mn), Molybdenum (Mo), Strontium (Sr), and Uranuim (U).

Beryllium (Be) and aluminium (Al) which is light metals sometimes are counted as heavy metals in view of their toxicity. Exposure to Beryllium (Be) can result in lung and heart disorder and possibly death while aluminium is a major inhibitor of crop growth in acid soils.

The most prevalent heavy metal known so far is Lead. Lead, is part of the component of tetra-ethyl lead that is extensively used in gasoline. Lead levels in the aquatic environments of industrialized societies have been estimated to be two to three times those of pre-industrialized areas. Although the use of leaded gasoline is largely been phased out in some advanced countries, but soils within the roads still retain high concentrations of lead.

BIOACCUMULATION OF HEAVY METALS

Bioaccumulation is the accumulation of substances or chemicals in an organism. There are small numbers of plants that easily absorb high levels of metals from the surrounding soil and other organisms that feed on plants which already has absorbed the metals and soil surroundings. These are called hyperaccumulators and accumulators respectively. If these plants and animals are harvested or collected for human use, exposure to harmful levels of metals can occur. This is normally concerned only to organisms collected from arrears with high concentration of the metals in the soil.

The uptake of metals by plants is dependent on the acidity of the soil (_PH). The higher the acidity, the more soluble and mobile the metals become, and the more likely they are to be taken up and accumulated in organisms.

In general, humans are more likely to be exposed to metal contamination from soil that sticks to plants and animals than from bioaccumulation. This is because it is very difficult to wash all soil particles off of plant and animal materials before preparing and ingesting those.

Organisms that feed and grow near the soil as well as the plant parts that have closer contact to the soil are at higher risk for exposure to metal contamination than the higher portions of plants and animals that stay further away. Animals can accumulate metals by eating plants, fish, soil, or drinking water with elevated metal concentration. These metals are not excreted by animals; rather, they accumulate mostly in organs as well as skin, hair, and bones.

EFFECTS OF HEAVY METALS ON LIVING ORGANISMS

Varying amount of heavy metals is required by living organisms. Iron, cobalt, copper, manganese, molybdenum, and zinc are required by humans. All metals are toxic at high concentrations. Excessive levels can be damaging to the organism. Other heavy metals such as mercury, plutonium, and lead are toxic metals and are of no importance or beneficial effect on organisms, and their accumulation over time in the bodies of animals can cause serious illness. The types of heavy metals and their effect on human health with their permissible limits are enumerated in the table below.

Permissible limits of heavy metals in respect to food

POLLUTANTS	MAJOR SOURCES	EFFECT ON HUMAN HEALTH	PERMISSIBLE LEVEL (mg/kg)
Arsenic	Pesticides, fungicides, metal smelters	Bronchitis, dermatitis, poisoning	0.02
Cadmium	Welding, electroplating, pesticide, fertilizer, Cd and Ni batteries, nuclear fission plant	Renal dysfunction, lung diseases, lung cancer, bone defects (Osteomalacia, Osteoporosis), increase blood pressure, kidney damage, bronchitis, gastrointestinal disorder, bone marrow, cancer	0.06
Lead	Paint, pesticide, smoking, automobile emission, mining, burning of coal	Mental retardation in children, development delay, fatal infant encephalopathy, congenital paralysis, sensor neural deafness and, acute or chronic damage to the nervous system, epilepticus, liver, kidney, gastrointestinal damage	0.1
Manganese	Welding, fuel addition, ferromanganese production	Inhalation or contact causes damage to central nervous system	0.26
Mercury	Pesticides, batteries, paper industry	Tremors, gingivitis, minor psychological changes, acrodynia characterized by pink hands and feet, spontaneous abortion, damage to nervous system, protoplasm poisoning	0.01
Zinc	Refineries, brass manufacture, metal plating, plumbing	Zinc fumes have corrosive effect on skin, cause damage to nervous membrane	15
Chromium	Mines, mineral sources	Damage to the nervous system, fatigue, irritability	0.05
Copper	Mining, pesticide production, chemical industry, metal piping	Anaemia, liver and kidney damage, stomach and intestinal irritation	0.1

 (Source: Singh et al., 2011)

Heavy metals disrupt metabolic functions in two ways:

·       They accumulate and thereby disrupt function in vital organs and glands such as the heart, brain, kidneys, bone, liver, etc.

·       They displace the vital nutritional minerals from their original place, thereby, hindering their biological function. It is, however, impossible to live in an environment free of heavy metals. There are many ways by which these toxins can be introduced into the body such as consumption of foods, beverages, skin exposure, and the inhaled air.

EFFECT OF HEAVY METALS IN THE ENVIRONMENT

Metal concentrate in soil typically ranges from less than one to as high as 100,000 mg/kg. Heavy metals are the main group of inorganic contaminants. Considerable large areas of land is contaminated with heavy metals due to use of sludge or municipal compost, pesticides, fertilisers, and emission from municipal wastes incinerates, exudates, residues from metalliferous mines and smelting industries.

Irrespective of origin of the metals in the soil, consequential effect of its high level occurrence can lead to soil quality degradation, crop yield reduction, and poor quality of agricultural products, posing significant hazards to human, animal, and ecosystem health.

BIOTOXICITY OF HEAVY METALS AND ITS POISONING

Heavy metals consumed beyond the bio-recommended limits become harmful and show some effect to life, this phenomenon is referred to as biotoxicity. Although individual metals exhibit specific signs of their toxicity, the following have been reported as general signs associated with cadmium, lead, arsenic, mercury, zinc, copper and aluminium poisoning: Gastrointestinal (GI) disorders, diarrhoea, stomatitis, tremor, hemoglobinuria causing a rust-red colour to stool, ataxia, paralysis, vomiting and convulsion, depression, and pneumonia when volatile vapours and fumes are inhaled. The nature of effects could be toxic (acute, chronic or sub-chronic), neurotoxic, carcinogenic, mutagenic or erotogenic.

Lead is the most significant toxin of the heavy metals, and the inorganic forms are absorbed through ingestion by food and water, and inhalation. A notably serious effect of lead toxicity is its teratogenic effect. Lead poisoning also causes inhibition of the synthesis of haemoglobin; dysfunctions in the kidneys, joints and reproductive systems, cardiovascular system and acute and chronic damage to the central nervous systems (CNS) and peripheral nervous system (PNS). Other effects include damage to the gastrointestinal tract (GIT) and urinary tract resulting in bloody urine, neurological disorder and can cause severe and permanent brain damage. While inorganic forms of lead, typically affect the CNS, PNS, GIT and other biosystems, organic forms predominantly affect the CNS. Lead affects children by leading to the poor development of the grey matter of the brain, thereby resulting in poor intelligence quotient (IQ). Its absorption in the body is enhanced by Ca and Zn deficiencies. Acute and chronic effects of lead result in psychosis.

Cadmium is toxic at extremely low levels. In humans, long term exposure results in renal dysfunction, characterized by tubular proteinuria. High exposure can lead to obstructive lung disease, cadmium pneumonitis, resulting from inhaled dusts and fumes. It is characterized by chest pain, cough with foamy and bloody sputum, and death of the lining of the lung tissues because of excessive accumulation of watery fluids. Cadmium is also associated with bone defects, viz; osteomalacia, osteoporosis and spontaneous fractures, increased blood pressure and myocardic dysfunctions. Depending on the severity of exposure, the symptoms of effects include nausea, vomiting, abdominal cramps, dyspnea and muscular weak-ness. Severe exposure may result in pulmonary odema and death. Pulmonary effects (emphysema, bronchiolitis and alveolitis) and renal effects may occur following sub-chronic inhalation exposure to cadmium and its compounds.

Zinc has been reported to cause the same signs of illness as does lead, and can easily be mistakenly diagnosed as lead poisoning. Zinc is considered to be relatively non-toxic, especially if taken orally. However, excess amount can cause system dysfunctions that result in impairment of growth and reproduction. The clinical signs of zinc toxicosis have been reported as vomiting, diarrhoea, bloody urine, icterus (yellow mucus membrane), liver failure, kidney failure and anaemia.

Mercury is toxic and has no known function in human biochemistry and physiology. Inorganic forms of mercury cause spontaneous abortion, congenital malformation and GI disorders (like corrosive esophagitis and hematochezia). Poisoning by its organic forms, which include monomethyl and dimenthylmecury presents with erthism (an abnormal irritation or sensitivity of an organ or body part to stimulation), acrdynia (pink disease, which is characterised by rash and desquamation of the hands and feet), gingivitis, stomatitis, neurological disorders, total damage to the brain and CNS and are also associated with congenital malformation.

Just like lead and mercury, arsenic toxicity symptoms depend on the chemical form ingested. Arsenic acts to coagulate protein, forms complexes with coenzymes and inhibits the production of adenosine triphosphate (ATP) during respiration. It is possibly carcinogenic in compounds of all its oxidation states and high level exposure can cause death. Arsenic toxicity also presents a disorder, which is similar to and often confused with Guillain-Barre syndrome, an anti-immune disorder that occurs when the body’s immune system mistakenly attacks part of the PNS, resulting in nerve inflammation that causes muscle weakness.

Copper though plays a vital role in facilitating the uptake of iron, but its deficiency can produce anaemia like symptoms, neutropenia, bone abnormalities, hypopigmentation, and impaired growth, increased incidence of infections, osteoporosis, hyperthyroidism, and abnormalities in glucose and cholesterol metabolism. Severe deficiency can possibly be found by testing for low plasma or serum copper levels, low ceruloplasmin, and low red blood cell superoxide dismutase levels, although, these are not sensitive to marginal copper statue. Copper salts are known to be toxic to humans possibly due to redox cycling and generation of reactive oxygen species that damage DNA. Corresponding amount of copper salts (30 mgkg-¹) are toxic to animals. Chronic copper toxicity does not normally occur in humans because of transport systems that regulate absorption and excretion.

Cobalt is an essential element for life when in minute quantity which is estimated to be between 150 and 500 mgkg^-1. However, chronic cobalt ingestion has caused serious health problems at doses far less than the lethal dose. Cobalt compound has led to peculiar form of toxin induced cardiomyopathy.

Manganese has a greater bioavailability in water than in diet. Higher levels of exposure to manganese in drinking water increases intellectual impairment and reduced intelligent quotients in school age children. Manganism is a rare neurological disorder associated with excessive manganese ingestion or inhalation. People at higher risk of exposure are workers are workers at manganese alloy production/processing plants. Manganism has a biphase disorder with early stage resulting to depression, mood swings, compulsive behaviour and psychosis if intoxicated. This early neurological symptoms give way to late stage manganism that resembles Parkinson’s disease. Symptoms include weakness, monotone and slow speech, an expressionless face, tremor, forward leaning gait, inability to walk backward without falling, rigidity and general problems with dexterity, gait and balance.

Iron toxicity occurs when there is free iron in the cell and it generally occurs when iron levels exceed the capacity of transferring to bind the iron. Iron when ingested in large amounts can cause excessive levels of iron in the blood thus reacting with peroxides to produce free radicals that are highly reactive and damages the DNA, proteins, lipids and other cellular components. Damage to the gastrointestinal tract prevents the regulated iron absorption leading to further increase in blood levels. Iron typically damages cells in the heart, liver, and elsewhere, which can cause significant adverse effects, including coma, metabolic acidosis, shock, liver failure, coagulopathy, adult respiratory distress syndrome, long time organ damage, and even death.

Nickel sulphide fume and dust are believed carcinogenic and various other nickel compounds may be as well. Nickel carbonyl (Ni (CO)₄) is an extremely toxic compound of nickel in gaseous state. The minimal risk level of nickel and its compounds is set to 0.0002 mgm^-3 for inhalation during 15-364 days while the tolerable upper dietary limit is 1 mgday^-1 and average ingestion is 0.069-0.162 mgday^-1 in US. Individuals that are sensitive to nickel may show allergy affecting their skin known as dermatitis. It is an important cause of contact allergy which are often marked by itchy red skin, partly due to its use in jewellery.

The poisoning effects of heavy metals are due to their interference with the normal body biochemistry in normal metabolic processes. When ingested, in the acid medium of the stomach, they are converted to their stable oxidation states (Zn²⁺, Pb²⁺, Cd²⁺, As²⁺, As³⁺, Hg²⁺, and Ag⁺) and combine with the body’s biomolecules such as proteins and enzymes to form strong and stable chemical bonds.

CONCLUSION

There is growing concern on effects of heavy metals on human health and hence this has led to increase in research upon the flora and fauna upon which humans feed.

In my research, THE USE OF GIANT AFRICAN SNAILS (Archachatina maginata) AND (Achatina folica) AS BIO-INDICATORS OF HEAVY METAL POLLUTION, the results confirmed that:

1.      They were concentration of heavy metals in both the flesh and shell of the organisms for copper, zinc, manganese, lead, cadmium, etc. It is an indication that organisms must have contacted the heavy metals throws the developmental process of hatching of the deposited egg, crawling for food on soils loaded with heavy metals, and feeding on plants that have already accumulated the same metals in the cells and tissues.

2.      The concentration varied from region and metals accounting for the effect of spillage, emission of hydrocarbon and exploration within the area which has found itself into the food chain that can affect us human while consuming the snails.

3.    Some areas in the south east have results that show that pollution during exploration of solid minerals, industrial activities like welding, pollution via landfills, addition of fertilisers to the soil that sometimes leach or washed by run off contributes to the pollution and are contacted by absorption, body surface contact like the case of Snails.

4.    Again, though some of these metals are vital nutrients in the body but when they are found beyond the quantity that the body needs it, it obviously become toxic or harmful.

RECOMMENDATION

Our food should be properly washed to ensure that the soil remains on the food (organisms) we intend to ingest which may contain the metals are washed off.

Though these snails are processed (heating, cooking) before consumption, the effect of processing could be minimal, since the heavy metals are non-degradable. Hence, it is advised that the source of snail to be consumed must be scrutinized.

Also, land pollution should be minimized and effluents should be treated before discharge unto land.

Application of manure and fertilizers as well as emission of gases should be controlled in order to reduce intentional heavy metal application to the soil.

More proactive measures should be employed or policies to regulate exploration of minerals that often spills and pollute the environment.

HumBioEnvLogy: Health and Environmental Effect of Uncontrolled Us...

HumBioEnvLogy: Health and Environmental Effect of Uncontrolled Us...: More awareness on the control use of chemicals (such as detergents) that pollutes the environment and affects human is of great concern...

Health and Environmental Effect of Uncontrolled Use of Chemical Based Detergent

More awareness on the control use of chemicals (such as detergents) that pollutes the environment and affects human is of great concern in the global context. Many laundry detergents contain approximately 35% to 75% phosphate salts. Phosphates cause a variety of water pollution problems. For example, phosphate tends to inhibit the biodegradation of organic substances. Non-biodegradable substances are not easily eliminated by public or private wastewater treatment. In addition, some phosphate-based detergents cause eutrophication. Over-enrichment of phosphate can cause the water body to become choked with algae and other plants. Eutrophication on the other hand deprives the water of available oxygen, causing the death of other organisms. Skins of human are affected in the use of the detergents and cancers arose when excessively ingested.

INTRO

Detergents figure in an extensive array of industrial and home cleaning applications, including laundry and dishwasher detergents. Released into the flow of wastewater coming from the home, these detergents can have far-reaching environmental impacts.

Although, detergents are obviously vital in the cleaning of the soiled oily rags and other domestic and industrial materials when they are dirty, as cleanliness is part of environmental friendliness. They are essential products that safeguard our health. Detergents are indispensable products for the maintenance of cleanliness, health and hygiene. But there is the need to look at how sustainable these detergents are to the environment and to man as they seem to do more harm than good.

Detergents unlike soaps that are made from natural substances are synthetic and are made of chemicals. Detergents came into brim light during world war due to the need for more soaps and better things that will clean the materials. This led to invent of the use of chemicals as against the natural agents used in soap making.

Aquatic organisms are in continuous danger and stand a chance of extinction due to the chemical deposits of some non-biodegradable chemicals that are major components/ingredients of detergents released into the water ways. The soil is also polluted with the reagents destroying the vital microorganisms needed in the soil as well increasing partly the activities of phytoplankton and other water algae/hyacinth, thus hindering the survival of zooplankton - in balance in the ecosystem.

These detergents have also caused lots of damage to the skin and eyes and caused lots of allergies to the external body while a high level contamination of the ingested ones causes cancer.

Alternative measures need to be applied to save our life and the environment from this silent but effective danger that are experienced from the use of detergent.

CONCEPT

Detergents are cleaning products manufactured from synthetic chemical compounds, as opposed to soap, which originates with natural substances like lye and plant saponins. Detergents are Sulfactants (compounds that lower the surface tension of a liquid, the interfacial tension between two liquids, or that between a liquid and a solid. Sulfactants may act as detergents and wetting agents, emulsifiers, foaming agents, and dispersants) or a mixture of surfactants with "cleaning properties in dilute solutions." These substances are usually alkylbenzenesulfonates, a family of compounds that are similar to soap but are more soluble in hard water, because the polar sulfonate (of detergents) is less likely than the polar carboxyl (of soap) to bind to calcium and other ions found in hard water. In most household contexts, the term detergent by itself refers specifically to laundry detergent or dish detergent, as opposed to hand soap or other types of cleaning agents. Detergents are commonly available as powders or concentrated solutions. Detergents, like soaps, work because they are amphiphilic: partly hydrophilic (polar) and partly hydrophonic (non-polar). Their dual nature facilitates the mixture of hydrophobic compounds (like oil and grease) with water. Because air is not hydrophilic, detergents are also foaming agents to varying degrees.

DETERGENT TYPES

Biological Detergent - Biological detergents are laundry detergents that contains enzymes harvested from micro-organisms such as bacteria adapted to live in hot springs. The description is commonly used in the United Kingdom, where other washing detergents are described as "non-biological" (or bio and "non-bio"). Most manufacturers of biological detergents also produce non-biological ones.

Biological detergents clean in the same way as non-biological ones with additional effects from the enzymes, whose purpose is to break down protein, starches and fat in dirt and stains on clothing to be laundered, for example food stains, sweat and mud. It is found that the performance of various makes of biological powders ranged from 58% to 81%, and non-biological powders scored from 41% to 70%. The enzymes in biological detergents enable effective cleaning at lower temperatures than required by normal detergents, but are denatured at higher temperatures—about 50°C is recommended. A biological detergent can contain amylase, cellulose, protease, and lipase.

Laundry Detergent - Laundry detergent, or washing powder, as otherwise called, is a type of detergent (cleaning agent) that is added for cleaning laundry. In common usage, "detergent" refers to mixtures of chemical compounds including alkylbenzenesulfonates, which are similar to soap but are less affected by hard water. In most household contexts, the term detergent refers to laundry detergent or other types of cleaning agents. Most detergent is delivered in powdered form.

DETERGENTS AS CHEMICALLY CLASSIFIED

Detergents are classified into Three (3) broad categories, depending on the sulfactants’ electrical charge. They are:

§  Anionic,

§  Cationic, and

§  Non-ionic and Zwitterionic detergents

Anionic Detergents - Typical anionic detergents are Alkyl benzene sulfonate. The alkyl benzene portion of these anions is lipophilic and the sulfonate is hydrophilic. Two different varieties have been popularized, those with branched alkyl groups and those with linear alkyl groups. The former were largely phased out in economically advanced societies because they are poorly biodegradable. An estimated 6 billion kilograms of anionic detergents are produced annually for domestic markets.

Bile acids, such as deoxycholic acid (DOC), are anionic detergents produced by the liver to aid in digestion and absorption of fats and oils.                  

Cationic Detergents - Cationic detergents are similar to the anionic ones, with a hydrophobic component, but, instead of the anionic sulfonate group, the cationic sulfactants have quaternary ammonium as the polar end. The ammonium center is positively charged.

Quaternary ammonium cations, also known as quats, are positively charged polyatomic ions of the structure NR⁺, R being an alkyl group or an aryl group.

Non-ionic and Zwitterionic detergents - Non-ionic detergents are characterized by their uncharged, hydrophilic head groups. Typical non-ionic detergents are based on polyoxyethylene or a glycoside. Common examples of the former include Tween, Triton, and the Brij series. These materials are also known as ethoxylates or PEGylates. Glycosides have a sugar as their uncharged hydrophilic headgroup. Examples include octyl-thioglucoside and maltoside. HEGA and MEGA series detergents are similar, possessing a sugar alcohol as headgroup.

Zwitterionic detergents possess a net zero charge arising from the presence of equal numbers of +1 and −1 charged chemical groups. Examples include CHAPS.

DETERGENTS COMPOSITION AND FUNCTION

Laundry detergents are formulated from six groups of substances which are discussed with their functions as:

Sulfactants – are organic chemicals, obtained through complex chemical reactions, from oil or  fat raw materials. They have wetting, emulsifying and dispersing properties, enabling the removal of dirt ("soil") from fabrics and keeping the soil suspended in the washing water.

Detergents usually contain several types of surfactants such as soaps (anionic), alkylbenzenesulphonate (anionic), ethoxylated fatty alcohols (non-ionic). The mixture is carefully balanced to control foaming and provide the appropriate washing efficiency (for the required washing temperatures, types of fabric and water hardness); at a price the consumer is willing to pay.

However, surfactant efficiency is very much reduced in hard water and their detergent properties are not complete even in soft water.

Builders – builders are key detergent components which remove the calcium and magnesium ions presents in hard water and in soils, thus lowering the concentration of surfactants necessary to perform the detersive action. Some builders also prevent the deposition of calcium and magnesium salts on fabrics and washing machines.

Sodium tripolyphosphate (STPP) is the most widely used builder and, in conjunction with surfactants, allows modern detergents to perform efficiently in all washing conditions, allowing the use of other essential ingredients to be minimised.

STTP also plays a number of other roles in detergents including maintaining alkalinity during washing (assists the removal of fatty soils), protecting the washing machine against corrosion, helping to suspend dirt in the wash water and prevent it redisposing on fabrics.

Zeolite A (a sodium aluminium silicate) is a synthetic builder, used in phosphate-free detergents, necessarily in conjunction with other chemicals. In most modern P-free detergents, zeolite is used with PCAs (polycarboxylates), but other chemicals have also been used in some detergents, for example NTA (nitrile tri acetic acid), EDTA, sodium carbonate, citrate, etc .

Zeolite absorbs, by ion-exchange, some of the calcium (but not the magnesium) presents in hard waters and soils, but the rate at which it is able to absorb calcium ions is many times slower than for STPP. Neither does it perform the other roles played by STPP in detergents. It is thus significantly less efficient than STPP and its use without any other change in the detergent formula would result in generally poor detergency and a severe increase of deposits on fabrics.

Bleaching agents – bleaching agents eliminate stubborn stains and ensure hygiene by killing bacteria through a chemical oxidation performed by a peroxygen generator, usually sodium perborate. The latter is usually active only above 60°C and so, for lower washing temperatures, an activator is added : eg. tetra acetyl ethylene diamine (TAED).

Enzymes – in particular: proteases, lipases and amylases. Catalyse the degradation of some stains and thus facilitate their elimination.

Other components – used in small quantities to ensure specific wash enhancing properties essentially include:

·       Enzyme stabilising agents ;

·       Fluorescent whitening agents which enhance the whiteness of fabrics and prevent natural yellowing ;

·       Anti-redeposition agents : cellulose derivatives (such as

carboxymethylcellulose) which help repel dirt from fabrics ;

·       Anti foams such as silicone to control the level of foam so that the

washing machine can operate properly ;

·       Perfumes ;

·       Corrosion inhibitors, such as sodium silicate.

Fillers – enable the adjustment of the active matter in the detergent to the doses used. Filler products include sodium sulphate in powders, water and solvents in liquids.

STPP (phosphates) fulfil several important functions in detergents:

§  Counteract the effects of calcium and magnesium salts present in hard water and in soils, thus allowing surfactants to function correctly. Phosphates prevent these ions combining with surfactants and rendering these inactive. They also condense to increase the surface activity of surfactants. Phosphates thus enable the detergent to actually wash correctly.

§  Prevent the deposit of calcium and magnesium incrustations on fabrics and on the washing machine’s heating elements.

§  Stabilise alkalinity at the correct level throughout the washing process thus giving good soil removal and enabling the other components of the detergents to function effectively.

§  "Anti-redeposition" properties. Phosphates help break up large particles of dirt into smaller ones, which can be washed out, and they help prevent fine dirt particles from combining and thus keep them in suspension in the wash water. Phosphates also help emulsify oily materials. Deposits on fabrics trap dirt and provide a breeding ground for bacteria. In addition, they cause washed fabrics to become harsh, grey, and to wear out more quickly.

§  Help the efficient manufacture, storage and use of detergents by stabilising detergents' physical properties.

§  Facilitate dissolving of detergents. Phosphates are highly soluble, and so facilitate and accelerate the dissolution of the detergent in the wash water, ensuring optimal performance. This is particularly important in tablet formulations, where the tablets must remain hard to handle, but dissolve very rapidly on contact with the wash water in order to disperse the concentrated surfactants they contain.

§  Redissolve calcium and magnesium compounds present in the washing machine from previous washes, thus reactivating any remaining detergents and improving detergent performance.

No other single chemical offers all, or even most, of these different properties, so that P-free detergents systematically contain a number of “new” chemicals as well as necessitating a complete change and reinforcement of other elements of the formulation.

APPLICATION/USES OF DETERGENTS

Biological Reagent

Reagent grade detergents are employed for the isolation and purification of integral membrane proteins found in biological cells. Advancements in the purity and sophistication of detergents have facilitated structural and biophysical characterization of important membrane proteins such as ion channels, transporters, signaling receptors, and photosystem II.

Biological detergents are commonly used to disrupt the bipolar lipid membrane of cells in order to release and solubilize membrane-bound proteins. Some detergents can be used to solubilize recombinant proteins, while others are recommended for the stabilization, crystallization, or denaturation of proteins. Detergents can align at aqueous/non-aqueous interfaces, resulting in reduced surface tension, increased miscibility, and stabilization of emulsions. Additional detergent applications include:

·         Extraction of DNA and RNA

·         Solubilization of specimens for diagnostic applications

·         Cell lysis

·         Liposome preparation

·         Prevention of reagent and analyte precipitation from solution

·         Prevention of non-specific binding in immunoassays

Fuel additives

Both carburettors and fuel injector components of auto engines benefit from detergents in the fuels to prevent fouling (the accumulation of unwanted material on solid surfaces to the detriment of function). Concentrations are about 300 ppm. Typical detergents are long-chain amines and amides such as poly-isobutane amine and poly-isobutene amide/succinimide.

Laundry detergents

One of the largest applications of detergents is for cleaning clothing. The formulations are complex, reflecting the diverse demands of the application and the highly competitive consumer market. In general, laundry detergents contain water softeners, surfactants, bleach, enzymes, brighteners, fragrances, and many other agents as had earlier been mentioned above. The formulation is strongly affected by the temperature of the cleaning water and varies from country to country.

Soapless soaps

Soapless soaps refer to soap free liquid cleanser (detergents or cleansing creams, other than soap, for cleaning the skin, especially removing greasy films or glandular exudates. Soap substitutes can be made from a variety of sources including plants with high saponin levels. Soap substitutes should not be confused with natural cleaning products which are cleaning agents for kitchen and house use) with a slightly acidic pH.

  

FORMULATION OF PHOSPHATE – FREE DETERGENTS

After 30 years of research no adequate substitute for STPP has been found: that is, a single substance which can take its place in a detergent formula without requiring other undesirable additions to the formula and without decreasing, below an acceptable level, the level of cleanliness and hygiene achieved.

In fact, a phosphate-free formula is usually completely different from a phosphate-containing one, using several new chemicals along with a different balance of existing ones, with a series of changes being necessary to resolve the succession of problems which arise when STPP is not used. Phosphate-free formulations as a general rule contain some or all of the following chemicals:

§  Zeolite A as a principal builder, this is an artificial, insoluble compound based on aluminium and silicate

§  PCAs (polycarboxylates), non-biodegradeable long chain petrochemical molecules, used to reduce deposition of calcium and magnesium salts which result from the poor ion removal properties of zeolite A

§  Reinforced surfactant system : higher total surfactant load and/or modified proportions of different surfactants

§  Increased enzyme content

§  Perborate activators added or levels increased to improve bleaching.

§  Sodium carbonate to maintain alkalinity

§  Small amounts or increased levels of organo-phosphates and citrates

EFFECT OF DETERGENT

Detergents are known to have caused lots of negative impacts both on Health and Environment. The important components of detergents forming sulfactants, builder and etc have been identified to affect human and environment. Detergents effect could be broadly classified as:

Health Effect

Sulfactants a major component of detergent is known to cause rough skin surface, the loss of natural moisture on the surface of the skin and increase the permeability of the outer skin surface. The test results show that human skin is only able to tolerate contact with chemicals contained in the detergent with irritation due to 'being' on the skin. Cationic surfactants are toxic if ingested compared with anionic surfactants and non-ionic. The rest of the ingredients contained in the detergent surfactants can form klorinisasi chlorbenzene in drinking water treatment process taps. Chlorbenzene is a chemical compound that is toxic and harmful to health. At first the type of ABS surfactants are widely used by industrial detergents. But because it found evidence that the ABS has a high risk to the environment, this material has now been replaced with another material that is less harmful.

Besides damaging the natural environment, the perceived adverse effects of detergents are not separated from its customers. The impact can also cause disturbances in the environment on human health. When after we wash clothes, our hands feel dry skin, burning, blistering, cracking, peeling easy to cause itching and sometimes become allergic.

Studies have shown that detergents has the ability to dissolve some essential ingredients in the body ( carcinogens, such as 3.4 Benzonpyrene) causing water to have odour and bad taste in addition disrupting the health stability of consumers as it later causes cancer.

Detergent decomposition process will result in residual benzene when reacted with chlorine to form chlorobenzene compounds these are very dangerous. Contact of benzene and chlorine are very likely to occur in drinking water treatment, considering the use of chlorine (which it contains chlorine) as a germ killer on the chlorination process.

Environmental (Aquatic Life) Effect

Phosphate, one of the most widely used builders in detergent formation is important as it is known to soften water and it reduces water. Phosphate is usually found in general form as Sodium Tripoly Phosphate (STPP). Phosphate is ordinarily not toxic but excess of it in the aquatic body causes eutrophication (nutrient enrichment) such that there will be oxygen deficiency resulting from algal (phytoplankton) growth and water hyacinth in the excess of food bacteria, thus exhausting the oxygen content of the water till a time the aquatic life becomes endangered and shades off light as sunlight will not penetrate into the water. This if not controlled have tendency of disrupting the ecosystem as it (water hyacinth) has already been found to block or hinder the flow of water from the channels causing flood. STPP has been bound from use in some countries and alternatively uses Zeolite and Citrate as Builder in detergent.

Generally, inflow or discharge of detergents into the water medium and soils poses a high threat to the environment as most of them contain ABS (alkyl benzene sulphate) which is non-biodegradable (non-decomposable by microorganisms) and is known to be a very toxic pollutant that threatens man and other organisms that depend on water for survival.

High phosphate detergent such as tri-sodium phosphate (TSP) is toxic when mixed with water as it destroy external mucus layers that protect fishes from bacteria and parasites and also damages the gills of fishes, this leads to the death of fishes while the low concentration of TSP kills the egg of fishes as such hinders the breeding ability of aquatic organisms.

Detergent also had a big hand in lowering water quality. Organic chemicals such as pesticides and phenols will be easily absorbed by fish, with only 2ppm concentrations of detergents can be absorbed by fish twice the amount of other chemicals. Detergents have negative effects on water biota. Phosphates in detergents can trigger freshwater algae to release toxins and deplete oxygen in the water. When algae decompose, they use the available oxygen to sustain life.

The materials used in packaging the detergents itself are of low quality that cannot be recycled and are found to be responsible in blocking the water channel and causing flood and other environmental impact.

SUGGESTED WAYS OF MINIMISING THE EFFECT

The ability of various detergents to remove dirt on the cloth or other object, reducing the presence of germs and bacteria that cause infections and increase the service life of fabrics, carpets, household appliances and other home appliances, is no doubt the major benefits of the use of detergents, thus becoming an important part that cannot be separated from the life of modern society.

Since the use of detergents have shown impact to the environment through poisoning of water in the treatment plant and water quality degradation, a substitute reagent with better characteristics like enzymes used in biological detergents ought to be employed as they may be easily decomposed by the micro-organisms as such making it environmentally friendly.

It will be very ideal if proper guidance and orientation be given to the consumers of these detergents as some of the detergents are health hazards that affect the skin and can even be poisonous when ingested. Specifications and proper directives need to be made to enable end users know the exact quantity that should be used and when as well as how. If this measure is properly taken, it will reduce foaming and bubbles and as such will not reduce the oxygen content of the aquatic habitat and saving the life of organisms therein. Proper awareness of how to dispose the sachets used in the packaging should be done and mostly conspicuously indicated on the sachets to enable end users stop littering them and discontinue it from blocking the water channel as well as suffocation of aquatic organisms.

More awareness on the benefits and impact of the use of washing machines need to be carried out as well as educating users on the need to be proactive and study the nature of the active ingredients in detergents they intend to purchase or use. In the same vein, strong policy should be enacted to control the use of non-environmental and non-healthy chemicals in the production of detergents and also to ensure that they use reagents and chemicals that will be good to the health of users. A clear environmental friendly logo should be marked clearly with green on the pack.

For further reading and references:-

Arnold, T., and Linke, D., Phase separation in the isolation and purification of membrane proteins. BioTechniques, 43, 427-440 (2007).

Celentano A, Sesana F, Settimi L, et al. Accidental exposures to liquid detergent capsules [Abstract 300]. 2012 International Congress of the European Association of Poisons Centres and Clinical Toxicologists; May 25–June 1, 2012; London, UK. Clin Toxicol 2012;50:353.

Garavito, R.M. and Ferguson-Miller, S., Detergents as tools in membrane biochemistry. J. Biol. Chem., 276, 32403-32406 (2001).

Helenius, A., et al., Properties of Detergents. Methods Enzymol., 56, 734-749 (1979).

Hjelmeland, L.M., Solubilization of native membrane proteins. Methods Enzymol., 182, 253-264 (1990).

McKenzie L, Ahir N, Stolz U, Nelson NG. Household cleaning product-related injuries treated in US emergency departments in 1990–2006. Pediatrics 2010;126:509.

Neugebauer, J.M., Detergents: an overview. Methods Enzymol., 182, 239-253 (1990). 

Williams H, Moyns E, Bateman DN, Thomas SH, Thompson JP, Vale JA. Hazard of household cleaning products: a study undertaken by the UK National Poisons Information Service. Clin Toxicol 2012;50:770–5.