THE EFFECT OF CALCIUM TAINTED WATER ON CADMIUM INDUCED LIVER DAMAGE

ABSTRACT

Cadmium is recognize has a toxicant to both human and it’s environment and recent investigations have shown its level of toxicity in association in liver damage.  The aim of study is to determine the effect of calcium tainted water on cadmium induced liver damage  have been examine in this studies, 20 female wistar rat were used in this study the rats divided into four groups each containing 5 rats per group . The group one was maintained on normal feed and water only, the group 2 were exposed to cadmium only while the group three were exposed to calcium only and the group four were exposed simultaneously to cadmium and calcium. Each of the animal was given treatment based on their body weight (0.9 mg per kg body weight). The treatments were administered to the animals once a day for two weeks. At the end of two weeks the animals were sacrificed and the following biochemical markers were measured; Alkaline phosphatase, total protein, alanine amino transferase, total bilirubin and direct bilirubin.  All the biochemical markers were negatively affected by cadmium with exception to Albumin and total protein. The study reveal that cadmium has the potential to induce hepatotoxicity and calcium tainted water offer little ameliorating affect to cadmium induce liver damage.

TABLE OF CONTENTS

Cover page

Certification……………………………………………………………i

Dedication……………………………………………………………..ii

Acknowledgement…………………………………………………….iii

Table of contents………………………………………………………iv

Abstracts………………………………………………………………vii

CHAPTER ONE

Introduction and literature review…………………………………….1

Cadmium………………………………………………………………3

Physical and chemical properties……………………………………..4

Occurance………………………………………………………………5

Biological role………………………………………………………….6

Cadmium poisoning……………………………………………………7

Calcium………………………………………………………………..11

Calcium compound……………………………………………………12

Nutrition ………………………………………………………………14

Bone health…………………………………………………………….16

Cardiovascular impact…………………………………………………16

Hazard and toxicity……………………………………………………….17

Hard water …………………………………………………………………18

Sources of hardness ……………………………………………………….18

Temporary hardness………………………………………………………..19

Permanent hardness………………………………………………………..20

Effect of hard water…………………………………………………………21

Health consideration………………………………………………………22

The liver…………………………………………………………………...23

Anatomy of the liver……………………………………………………..24

Diseases of the liver………………………………………………………29

Liver function test………………………………………………………30

CHAPTER TWO

Materials and methods…………………………………………………35

Materials……………………………………………………………….35

Animals……………………………………………………………….36

Preparation of contaminated water………………………………….36

Treatment of animal…………………………………………………37

Preparation of seral sample…………………………………………..37

Preparation of tissue homogenates………………………………….37

Biochemical analyses………………………………………………….38

CHAPTER THREE

Results………………………………………………………………….46

CHAPTER FOUR

Discussion……………………………………………………………….53

Conclussion……………………………………………………………..54

References ……………………………………………………………...55

Appendix i………………………………………………………………66

Appendix ii……………………………………………………………..68

Appendix iii…………………………………………………………… 70

Appendix iv…………………………………………………………….75

Appendix v……………………………………………………………..79

CHAPTER ONE

1.0     INTRODUCTION AND LITERATURE REVIEW

Heavy metals are toxic agent. They are toxic to humans and animals. Heavy metals which establishes toxic actions to humans include; cadmium (Stohs and Bagchi,1995), lead ( Ferner, 2001) and mercury (Hawkes, 1997). Each of these has been studied   in isolation for toxicity (Huton and Symon, 1986; Nriagu and Pacyna, 1988; Nriagu, 1989). But, in the eco-system, be it air, atmosphere, land, and water where they occur, they do not exist in isolation. They occur in close association with other metal and non-metallic elemental pollutants. Among the metallic pollutant could be calcium, copper, zinc, magnesium, manganese, iron and others.  Metals are known to interact with one another. The interaction can bring two elements together in close proximity or it could cause out right displacement of one another. When ingested together in food and water, they antagonize each other. When it comes to intestinal and pulmonary absorption, it is therefore conceivable that the presence of other elements can the toxic potential of each of the heavy metals that have been studied in isolation.

          Eborge (1994) reported that warri river has an unacceptable high cadmium level, 0.3 mg cadmium per liter of water which was 60 folds above the maximum allowable level of 0.005 mg per liter. This report prompted our earlier studies on the hepato, nephro and gonadial toxicity of cadmium. In rats exposed to this high dose via water and diet, the diet was formulated with feed exposed to 0.3 mg cadmium per water. In the ambient water as protein source and the toxic effect investigated and reported (Asagba and obi 2000; Asagba and Obi 2001; Obi and Ilori 2002; Asagba and Obi 2004a; Asagba and Obi 2004b; Asagba and Obi 2005).The study focus on cadmium without taking into consideration the fact that other metals were also present in the river water, and as such were co-consumed by the communities using the river water for cooking drinking and for other domestic purposes. Hence, it is desirable to know if the presence of other metals would enhance or diminish the toxic potential of cadmium or indeed if any other heavy metals such as lead that was mentioned above. Therefore, the aim of the present study was to re-examine the toxic potential of cadmium in the presence of other metals such as calcium and magnesium.

          The objectives set out to achieve were;

1.     Re-examination of toxicity of using established and those for liver toxicity namely; blood alanine amino transferase and aspartate amino transferase, alkaline phosphatase, bilirubin, albumin and total protein.

2.     Re-examine the status parameter in the absence of cadmium but in the presence of calcium or magnesium or both.

3.     Re-examine this parameters in the presence of cadmium, calcium and magnesium.

1.1     CADMIUM

Cadmium is a chemical element with symbol Cd and atomic number 48. This soft, bluish-white metal is chemically similar to the two other stable metals in group 12, zinc and mercury. Like zinc, it prefers oxidation state +2 in most of its compounds and like mercury it shows a low melting point compared to transition metals. Cadmium and its congeners are not always considered transition metals, in that they do not have partly filled d or f electron shells in the elemental or common oxidation states. The average concentration of cadmium in Earth's crust is between 0.1 and 0.5 parts per million (ppm). It was discovered in 1817 simultaneously by Stromeyer and Hermann, both in Germany, as an impurity in zinc carbonate. Cadmium occurs as a minor component in most zinc ores and therefore is a byproduct of zinc production. It was used for a long time as a pigment and for corrosion-resistant plating on steel, whereas cadmium compounds were used to stabilize plastic. The use of cadmium is generally decreasing due to its toxicity (it is specifically listed in the European Restriction of Hazardous Substances (Morrow, 2010)) and the replacement of nickel-cadmium batteries with nickel-metal hydride and lithium-ion batteries. One of its few new uses is in cadmium telluride solar panels. Although cadmium has no known biological function in higher organisms, a cadmium-dependent carbonic anhydrase has been found in marine diatoms.

1.1.1  PHYSICAL PROPERTIES

Cadmium is a soft, malleable, ductile, bluish-white divalent metal. It is similar in many respects to zinc but forms complex compounds (Holleman et al., 1985). Unlike other metals, cadmium is resistant to corrosion and as a result it is used as a protective layer when deposited on other metals. As a bulk metal, cadmium is insoluble in water and is not flammable; however, in its powdered form it may burn and release toxic fumes (CSEM, 2011).

1.1.2  CHEMICAL PROPERTIES

Although cadmium usually has an oxidation state of +2, it also exists in the +1 state. Cadmium and its congeners are not always considered transition metals, in that they do not have partly filled d or f electron shells in the elemental or common oxidation states (Cotton, 1999). Cadmium burns in air to form brown amorphous cadmium oxide (CdO); the crystalline form of this compound is a dark red which changes color when heated, similar to zinc oxide. Hydrochloric acid, sulfuric acid and nitric acid dissolve cadmium by forming cadmium chloride (CdCl₂), cadmium sulfate (CdSO₄), or cadmium nitrate (Cd(NO₃)₂). The oxidation state +1 can be reached by dissolving cadmium in a mixture of cadmium chloride and aluminium chloride, forming the Cd₂²⁺ cation, which is similar to the Hg₂²⁺ cation in mercury(I) chloride (Holleman et al., 1985).

Cd + CdCl₂ + 2 AlCl₃ → Cd₂(AlCl₄)₂

The structures of many cadmium complexes with nucleobases, amino acids and vitamins have been determined (Carballo et al., 2013).

1.1.3  OCCURRENCE

Cadmium metal

Cadmium makes up about 0.1 ppm of Earth's crust. Compared with the more abundant 65 ppm zinc, cadmium is rare (Wedepohl, 1995). No significant deposits of cadmium-containing ores are known. Greenockite (CdS), the only cadmium mineral of importance, is nearly always associated with sphalerite (ZnS). This association is caused by the geochemical similarity between zinc and cadmium which makes geological separation unlikely. As a consequence, cadmium is produced mainly as a byproduct from mining, smelting, and refining sulfidic ores of zinc, and to a lesser degree, lead and copper. Small amounts of cadmium, about 10% of consumption, are produced from secondary sources, mainly from dust generated by recycling iron and steel scrap. Production in the United States began in 1907, (Ayres et al., 2003) but it was not until after World War I that cadmium came into wide use (Plachy, 1998). One place where metallic cadmium can be found is the Vilyuy River basin in Siberia (Fthenakis, 2004).

Rocks mined to produce phosphate fertilizers contain varying amounts of cadmium, leading to a cadmium concentration of up to 300 mg/kg in the produced phosphate fertilizers and thus in the high cadmium content in agricultural soils (Grant and Shepperd , 2008). Coal can contain significant amounts of cadmium, which ends up mostly in the flue dust (Bettinelli et al., 1988).

1.1.4  BIOLOGICAL ROLE

Cadmium has no known useful role in higher organisms, (Hogan, 2010) but a cadmium-dependent carbonic anhydrase has been found in some marine diatoms (Lane et al., 2005). The diatoms live in environments with very low zinc concentrations and cadmium performs the function normally carried out by zinc in other anhydrases. The discovery was made using X-ray absorption fluorescence spectroscopy (XAFS) (Lane et al., 2000).

The highest concentration of cadmium has been found to be absorbed in the kidneys of humans, and up to about 30 mg of cadmium is commonly inhaled throughout childhood and adolescence (Perry et al., 1976). Cadmium can be used to block calcium channels in chicken neurons (Swandulla and Armstrong, 1989). Analytical methods for the determination of cadmium in biological samples have been reviewed (klorz et al., 2013).

1.1.5  ENVIRONMENT

The biogeochemistry of cadmium and its release to the environment has been the subject of review, as has the speciation of cadmium in the environment (Cullen et al., 2013).

1.1.6  CADMIUM POISONING

The bioinorganic aspects of cadmium toxicity have been reviewed (Maret et al., 2013).The most dangerous form of occupational exposure to cadmium is inhalation of fine dust and fumes, or ingestion of highly soluble cadmium compounds.  Inhalation of cadmium-containing fumes can result initially in metal fume fever but may progress to chemical pneumonitis, pulmonary edema, and death (Hayes, 2007). Cadmium is also an environmental hazard. Human exposures to environmental cadmium are primarily the result of fossil fuel combustion, phosphate fertilizers, natural sources, iron and steel production, cement production and related activities, nonferrous metals production, and municipal solid waste incineration.  Bread, root crops, and vegetables also contribute to the cadmium in modern populations (Mann, 2012). There have been a few instances of general population toxicity as the result of long-term exposure to cadmium in contaminated food and water, and research is ongoing regarding the estrogen mimicry that may induce breast cancer (Mann, 2012). In the decades leading up to World War II, mining operations contaminated the Jinzū River in Japan with cadmium and traces of other toxic metals. As a consequence, cadmium accumulated in the rice crops growing along the riverbanks downstream of the mines. Some members of the local agricultural communities consuming the contaminated rice developed itai-itai disease and renal abnormalities, including proteinuria and glucosuria (Nogawa et al., 2004).

Jinzū River area, which was contaminated with cadmium

The victims of this poisoning were almost exclusively post-menopausal women with low iron and other mineral body stores. Similar general population cadmium exposures in other parts of the world have not resulted in the same health problems because the populations maintained sufficient iron and other mineral levels. Thus, although cadmium is a major factor in the itai-itai disease in Japan, most researchers have concluded that it was one of several factors. Cadmium is one of six substances banned by the European Union's Restriction on Hazardous Substances (RoHS) directive, which bans certain hazardous substances in electrical and electronic equipment but allows for certain exemptions and exclusions from the scope of the law. The International Agency for Research on Cancer has classified cadmium and cadmium compounds as carcinogenic to humans. Although occupational exposure to cadmium is linked to lung and prostate cancer, there is still a substantial controversy about the carcinogenicity of cadmium in low, environmental exposure. Recent data from epidemiological studies suggest that intake of cadmium through diet associates to higher risk of endometrial, breast and prostate cancer as well as to osteoporosis in humans (Julin et al., 2012). A recent study has demonstrated that endometrial tissue is characterized by higher levels of cadmium in current and former smoking females (Rzymski et al., 2014). Although some epidemiological studies show a significant correlation between cadmium exposure and occurrence of disease conditions in human populations, a causative role for cadmium as the factor behind these effects remains yet to be shown. In order to prove a causative role, it will be important to define the molecular mechanisms through which cadmium in low exposure can cause adverse health effects. One hypothesis is that cadmium works as an endocrine disruptor because some experimental studies have shown that it can interact with different hormonal signaling pathways. For example, cadmium can bind to the estrogen receptor alpha, (Fechner et al., 2011) and affect signal transduction along the estrogen and MAPK signaling pathways at low doses (Ali et al., 2010).

Tobacco smoking is the most important single source of cadmium exposure in the general population. It has been estimated that about 10% of the cadmium content of a cigarette is inhaled through smoking. The absorption of cadmium from the lungs is much more effective than that from the gut, and as much as 50% of the cadmium inhaled via cigarette smoke may be absorbed (Friberg, 1983). On average, smokers have 4–5 times higher blood cadmium concentrations and 2–3 times higher kidney cadmium concentrations than non-smokers. Despite the high cadmium content in cigarette smoke, there seems to be little exposure to cadmium from passive smoking. No significant effect on blood cadmium concentrations has been detected in children exposed to environmental tobacco smoke.  In the non-smoking part of the population food is the biggest source of exposure to cadmium. High quantities of cadmium can be found for example in crustaceans, molluscs, offals, and algal products. However, due to the higher consumption the most significant contributors to the dietary cadmium exposure are grains, vegetables, and starchy roots and tubers. Cadmium exposure is a risk factor associated with early atherosclerosis and hypertension, which can both lead to cardiovascular disease (Jarup, 1998).

1.2     CALCIUM

Calcium is a chemical element with symbol Ca and atomic number 20. Calcium is a soft gray alkaline earth metal, and is the fifth-most-abundant element by mass in the Earth's crust. Calcium is also the fifth-most-abundant dissolved ion in seawater by both molarity and mass, after sodium, chloride, magnesium, and sulfate (Dickson and Goyet 1994). Calcium is essential for living organisms, in particular in cell physiology, where movement of the calcium ion Ca²⁺ into and out of the cytoplasm functions as a signal for many cellular processes. As a major material used in mineralization of bone, teeth and shells, calcium is the most abundant metal by mass in many animals.

1.2.1  CALCIUM COMPOUNDS

• Calcium carbonate (CaCO₃) is used in manufacturing cement and mortar, lime, limestone (usually used in the steel industry) and aids in production in the glass industry. It also has chemical and optical uses as mineral specimens in toothpastes, for example.
• Calcium hydroxide solution (Ca (OH)₂) (also known as limewater) is used to detect the presence of carbon dioxide by being bubbled through a solution. It turns cloudy where CO₂ is present.
• Calcium arsenate (Ca₃ (AsO₄)₂) is used in insecticides.
• Calcium carbide (CaC₂) is used to make acetylene gas (for use in acetylene torches for welding) and in the manufacturing of plastics.
• Calcium chloride (CaCl₂) is used in ice removal and dust control on dirt roads, in conditioner for concrete, as an additive in canned tomatoes, and to provide body for automobile tires.
• Calcium citrate (Ca₃ (C₆H₅O₇)₂) is used as a food preservative.
• Calcium cyclamate (Ca (C₆H₁₁NHSO₃)₂) is used as a sweetening agent in several countries. In the United States it is no longer permitted for use because of suspected cancer-causing properties (Newton, 2009).
• Calcium gluconate (Ca (C₆H₁₁O₇)₂) is used as a food additive and in vitamin pills.
• Calcium hypochlorite (Ca(OCl)₂) is used as a swimming pool disinfectant, as a bleaching agent, as an ingredient in deodorant, and in algaecide and fungicide.
• Calcium permanganate (Ca (MnO₄)₂) is used in liquid rocket propellant, textile production, as a water sterilizing agent and in dental procedures.
• Calcium phosphate (Ca₃(PO₄)₂) is used as a supplement for animal feed, fertilizer, in commercial production for dough and yeast products, in the manufacture of glass, and in dental products.
• Calcium phosphide (Ca₃P₂) is used in fireworks, rodenticide, torpedoes and flares.
• Calcium stearate (Ca(C₁₈H₃₅O₂)₂) is used in the manufacture of wax crayons, cements, certain kinds of plastics and cosmetics, as a food additive, in the production of water resistant materials and in the production of paints.
• Calcium sulfate (CaSO₄·2H₂O) is used as common blackboard chalk, as well as, in its hemihydrate form better known as Plaster of Paris.
• Calcium tungstate (CaWO₄) is used in luminous paints, fluorescent lights and in X-ray studies.
• Hydroxylapatite (Ca₅ (PO₄)₃(OH), but is usually written Ca₁₀ (PO₄)₆(OH)₂) makes up seventy percent of bone. Also carbonated-calcium deficient hydroxylapatite is the main mineral of which dental enamel and dentin are comprised.

1.2.2   NUTRITION

Calcium is an important component of a healthy diet and a mineral necessary for life. The National Osteoporosis Foundation says, "Calcium plays an important role in building stronger, denser bones early in life and keeping bones strong and healthy later in life." Approximately 99 percent of the body's calcium is stored in the bones and teeth. The rest of the calcium in the body has other important uses, such as some exocytosis, especially neurotransmitter release, and muscle contraction. In the electrical conduction system of the heart, calcium replaces sodium as the mineral that depolarizes the cell, proliferating the action potential. In cardiac muscle, sodium influx commences an action potential, but during potassium efflux, the cardiac myocyte experiences calcium influx, prolonging the action potential and creating a plateau phase of dynamic equilibrium. Long-term calcium deficiency can lead to rickets and poor blood clotting and in case of a menopausal woman, it can lead to osteoporosis, in which the bone deteriorates and there is an increased risk of fractures. While a lifelong deficit can affect bone and tooth formation, over-retention can cause hypercalcemia (elevated levels of calcium in the blood), impaired kidney function and decreased absorption of other minerals (Catharine et al., 2011). Several sources suggest a correlation between high calcium intake (2000 mg per day, or twice the U.S. recommended daily allowance, equivalent to six or more glasses of milk per day) and prostate cancer (giovannucci et al., 1998).  Dairy products, such as milk and cheese, are a well-known source of calcium. Some individuals are allergic to dairy products and even more people, in particular those of non Indo-European descent, are lactose-intolerant, leaving them unable to consume non-fermented dairy products in quantities larger than about half a liter per serving. Others, such as vegans, avoid dairy products for ethical and health reasons. Many good vegetable sources of calcium exist, including seaweeds such as kelp, wakame and hijiki; nuts and seeds like almonds, hazelnuts, sesame, and pistachio; blackstrap molasses; beans (especially soy beans); figs; quinoa; okra; rutabaga; broccoli; dandelion leaves; and kale. In addition, several foods and drinks, such as orange juice, soy milk, tofu, breakfast cereals, and breads are often fortified with calcium. Numerous vegetables, notably spinach, chard and rhubarb have a high calcium content, but they may also contain varying amounts of oxalic acid that binds calcium and reduces its absorption. The same problem may to a degree affect the absorption of calcium from amaranth, collard greens, and chicory greens. This process may also be related to the generation of calcium oxalate.

An overlooked source of calcium is eggshell, which can be ground into a powder and mixed into food or a glass of water (Schaafsma et al., 2002). The calcium content of most foods can be found in the USDA National Nutrient Database.

1.2.3  BONE HEALTH

Calcium supplementation can have a small effect in improving bone mineral density. This is of no meaningful benefit to health in children, but in post-menopausal women the risk of vertebral fractures may be reduced (Shea et al., 2004).

1.2.4  CARDIOVASCULAR IMPACT

A study investigating the effects of personal calcium supplement use on cardiovascular risk in the Women’s Health Initiative Calcium/Vitamin D Supplementation Study (WHI CaD Study) found a modestly increased risk of cardiovascular events, particularly myocardial infarction in postmenopausal women. A broad recommendation of calcium/vitamin D supplements is therefore not warranted.  In contrast, the authors of a 2013 literature review concluded that the benefits of calcium supplementation, such as on bone health, appear to outweigh any risk calcium supplementation may theoretically pose to the cardiovascular health (Downing and Islam 2013).

1.2.5  HAZARDS AND TOXICITY

Compared with other metals, the calcium ion and most calcium compounds have low toxicity. This is not surprising given the very high natural abundance of calcium compounds in the environment and in organisms. Calcium poses few serious environmental problems, with kidney stones the most common side-effect in clinical studies. Acute calcium poisoning is rare, and difficult to achieve unless calcium compounds are administered intravenously. For example, the oral median lethal dose (LD⁵⁰) for rats for calcium carbonate and calcium chloride are 6.45 and 1.4 g/kg, (Lewis, 1996) respectively.

Calcium metal is hazardous because of its sometimes-violent reactions with water and acids. Calcium metal is found in some drain cleaners, where it functions to generate heat and calcium hydroxide that saponifies the fats and liquefies the proteins (e.g., hair) that block drains. When swallowed calcium metal has the same effect on the mouth, esophagus and stomach, and can be fatal (Rumack, 2010).

1.3     HARD WATER

Hard water is water that has high mineral content (in contrast with "soft water"). Hard water is formed when water percolates through deposits of calcium and magnesium-containing minerals such as limestone, chalk and dolomite. Hard drinking water is generally not harmful to one's health, (WHO, 2003) but can pose serious problems in industrial settings, where water hardness is monitored to avoid costly breakdowns in boilers, cooling towers, and other equipment that handles water. In domestic settings, hard water is often indicated by a lack of suds formation when soap is agitated in water, and by the formation of limescale in kettles and water heaters. Wherever water hardness is a concern, water softening is commonly used to reduce hard water's adverse effects.

1.3.1  SOURCES OF HARDNESS

Water's hardness is determined by the concentration of multivalent cations in the water. Multivalent cations are cations (positively charged metal complexes) with a charge greater than 1+. Usually, the cations have the charge of 2+. Common cations found in hard water include Ca²⁺ and Mg²⁺. These ions enter a water supply by leaching from minerals within an aquifer. Common calcium-containing minerals are calcite and gypsum. A common magnesium mineral is dolomite (which also contains calcium). Rainwater and distilled water are soft, because they contain few ions (Hermann, 2006).

The following equilibrium reaction describes the dissolving and formation of calcium carbonate :

CaCO₃ (s) + CO₂ (aq) + H₂O (l) ⇋ Ca²⁺ (aq) + 2HCO₃⁻ (aq)

The reaction can go in either direction. Rain containing dissolved carbon dioxide can react with calcium carbonate and carry calcium ions away with it. The calcium carbonate may be re-deposited as calcite as the carbon dioxide is lost to atmosphere, sometimes forming stalactites and stalagmites.

Calcium and magnesium ions can sometimes be removed by water softeners

1.3.2  TEMPORARY HARDNESS

Temporary hardness is a type of water hardness caused by the presence of dissolved bicarbonate minerals (calcium bicarbonate and magnesium bicarbonate). When dissolved, these minerals yield calcium and magnesium cations (Ca²⁺, Mg²⁺) and carbonate and bicarbonate anions (CO₃^2-, HCO₃^-). The presence of the metal cations makes the water hard. However, unlike the permanent hardness caused by sulfate and chloride compounds, this "temporary" hardness can be reduced either by boiling the water, or by the addition of lime (calcium hydroxide) through the softening process of lime softening, (Christian et al., 2005) Boiling promotes the formation of carbonate from the bicarbonate and precipitates calcium carbonate out of solution, leaving water that is softer upon cooling.

Buyers has the right to create dispute within seven (7) days of purchase for 100% refund request when you experience issue with the file received. 

Dispute can only be created when you receive a corrupt file, a wrong file or irregularities in the table of contents and content of the file you received. 

ProjectShelve.com shall either provide the appropriate file within 48hrs or send refund excluding your bank transaction charges. Term and Conditions are applied.

Buyers are expected to confirm that the material you are paying for is available on our website ProjectShelve.com and you have selected the right material, you have also gone through the preliminary pages and it interests you before payment. DO NOT MAKE BANK PAYMENT IF YOUR TOPIC IS NOT ON THE WEBSITE.

In case of payment for a material not available on ProjectShelve.com, the management of ProjectShelve.com has the right to keep your money until you send a topic that is available on our website within 48 hours.

You cannot change topic after receiving material of the topic you ordered and paid for.