?Question 1a) .
Fertilizer on the fields would contain phosphates. As arsenic and phosphate are in the same group in the periodic table they compete against each other in binding to iron (III) hydroxide. Arsenic is replaced on iron (III) hydroxide by phosphorus and arsenic is released into surrounding water. A rice field containing stagnant water would be an anaerobic environment and therefore a reducing one. This environment enables anaerobic bacteria to metabolize arsenic particles into a soluble state by making them less oxidized. Arsenic would also be contained in water used to irrigate these fields as it would come from wells nearby, making a vicious circle of arsenic contamination.b) Sulfide minerals contain arsenic.
When minerals such as pyrite become oxidized, iron(III) hydroxide is produced and the arsenic contained in minerals binds to the surface of the iron (adsorbtion) and is carried into the groundwater. Iron(III) hydroxide coats the grains of sediment in groundwater, storing arsenic until the right conditions allow its release. The arsenic that had been adsorbed can be displaced back into the surrounding water by a chemical change which causes the coating of iron(III) hydroxide to break down.c) The sediments from densely vegetated lands will have been in an anaerobic environment.
The breaking down of dead plant materials by aerobic bacteria consumes all available oxygen in areas of stagnant water. These sediments will contain arsenic in its most soluble, least oxidized form. It will also contain iron(III) hydroxide and pyrite which will give rise to conditions for making arsenic available to the groundwater and as in all the above situations, able to filter through into the water in shallow wells.Question 2a) Three assumptions that need to be made in order for the data from West Bengal and Taiwan to be able to be applied to the case in Hanoi are:-that the women of Hanoi are as susceptible to the effects of arsenic as those of West Bengal and Taiwan.
– That the women of Hanoi have the same lifestyle as those in the previous studies and drink the same amount of water.- That the subjects involved drink from the same wells for the period of the study and the levels of arsenic they are drinking remain constantTable 2?Number of wells affected by different ranges of arsenic concentration, for the 5 areas of Hanoi.Number of affected wellsArsenic concentration range/mg l?1Rural suburb ARural suburb BRural suburb CRural suburb DHanoi urban areaTotal300001506Total201618152392Table 3 Estimates of exposure to arsenic contamination from drinking well water and the likely consequences for female inhabitants of Hanoi, Vietnam. (Note: skin keratoses commonly lead to skin cancer.)Arsenic concentration range/mg l?1Exposure to As/% (number) of affected wellsLikely incidence of keratosis/age adjusted %Likely age-adjusted mortality from kidney cancer/deaths per 105 individualsLikely age-adjusted mortality from lung cancer/deaths per 105 individuals3006.5216.32052Total99.
99Not applicableNot applicableNot applicablec) The presence of arsenic in groundwater will always pose a risk to those who consume it. In Hanoi those living in the south are living in an area with high concentrations of arsenic in the groundwater. These people will be at higher risk of developing cancers than those in the north but as most of the wells in Hanoi contain concentrations of arsenic above the recommended safe levels given by the World Health Organisation many are at risk across the city and its suburbs. 10?µg 1-? is the maximum level of arsenic recommended by the WHO as safe to drink. Even at these low levels there is a possibility of 9/100000 people developing cancers which is a large enough chance for the water to be considered unsafe.
Some local governments suggest that arsenic below 50?µg 10-? is a safe level but studies have shown that being exposed to levels this high cause more keratosis and cancers than at lower levels.The highest levels in Hanoi are found in the south of the country close to a river which empties into the sea. This river flows through the city of Hanoi and possibly washes the effluent from heavy industry into the river. This looks to contain chemicals which allow arsenic to enter the groundwater and pollute the wells of the people living in the area. The naturally occurring arsenic in the sediment and rocks in the river will be released when chemicals such as phosphorus from farming and industry are introduced into its environment. When this enters groundwater it contaminates wells that are shallow enough so that the arsenic has not filtered through rocks and sediments that may have readsorbed it into their chemical coatings. Figure 1 does not show the depths of the wells involved in the study but the reason for the lower concentrations of arsenic in suburb D may be due to their distance from the source of contamination or their depth.Suburbs A and C have the highest numbers of low concentration wells.
Their position above the flow of the polluted river may be the cause for this. Less pollutants flowing into the groundwater in these areas will mean less ability for arsenic to be released. The city of Hanoi has relatively low levels of arsenic concentrations in its wells.
This may be due to the economy of the city making it possible to have pollutants disposed of safely and there being paved surfaces and less vegetation to minimize the possibility of there being stagnant water to create reducing conditions for the release of arsenic. The urban area may have regular testing of the chemicals in the water and regulate the concentrations of arsenic. Where most of the wells are within the limits set by the government in Bangladesh, it is possible that Vietnam has similar limits and the wells within the city are kept within these boundaries.
With many wells above the safe limit set by the WHO and above those that have been seen to cause chronic arsenosis in people in Bangladesh and West Bengal then it can be said that the arsenic poses a considerable risk to those in Hanoi. Any risk of arsenic poisoning is, as with any risk of BSE, to much of a risk and there should be measures taken to end the risk wherever possible.Question 3 Ai) A standardized product is one that would have the same amount and type of chemical in every pill. To be able to draw conclusions from a study a standardized product should be used so as to give clear indications of what a certain amount and concentration of chemical can do.Aii) A scientific study to test the effects of red clover would have to start with identifying the active ingredients with in the extract to be used. This would give some indications as to what effects to expect and would check for any ingredients which may be poisonous if consumed by humans or animals.
Once the extract had been analyzed, a standardized form of the extract should be produced to allow for less variation in the outcomes. Although some people disagree, the clover extract might then be tested on animals (T4 p62) such as rats to ensure it is safe for human consumption and to observe whether some of the expected effects take place. When testing on animals it may be possible to test the extract during pregnancy as there will is no chance to do this in human trials.
In testing red clover extract for the effects on menopausal symptoms a large group of menopausal and premenopausal women who are experiencing menopausal symptoms may be needed. It might also be useful to find equal numbers of women who are taking HRT and those who are not. This difference would show whether the red clover extract is compatible with HRT and whether it has additional benefits. A clinical trial should be set up using the red clover extract and a placebo (T4 p60).
The use of a placebo within the trial acts as a control. When the subjects of the trial take the placebo they may still experience some relief from their symptoms (T4 p60). This may be less likely with physical symptoms than with emotional ones but it is still important to have a control within the study to ensure clear results.
The study may need to take place over a number of weeks, recording changes to symptoms throughout to establish the effect the extract has on the symptoms of menopause. This is because it may not be clear how long the extract will take to have any effect and will be long enough to recognize any side effects there may be. At the end of the study the findings should be compared with the expectations formed at each stage of the testing process and a record of all the effects and side effects of the extract made to see if it is safe to use and effective for the purpose striven for.Bi) Phylogenetic knowledge helps pharmaceutical companies in their exploration of compounds by allowing them to form expectations of how a plant compound will act based on how others in the same family act as they may all have evolved from a common ancestor. Dong quai is from the same family as silphion and will most likely have the same properties as an abortifacient.
It is in the same family as silphion as it will have the same physical and chemical characteristics, grooved stems and characteristic round flower heads. As silphion was a much sought after plant due to its many uses it would be a plant that may be widely used in developing drugs today. As it is extinct this is no longer possible but knowing the appearance of the plant aids in identifying it??™s family and therefore other plants that may have its same properties for use in drugs today. ii) Isoflavones in herbal remedies may be affecting the hormone balance in people who are taking them in menopausal drugs. Plants which contain isoflavones have been seen to cause fertility problems in cattle that have grazed on them. This will not cause concern for women taking the drugs for their menopausal symptoms as they have become infertile due to their menopause but this indicated that the isoflavones are mimicking the oestrogen and progesterone in the body and effecting endocrine function. HRT is a drug that replaces low levels of oestrogen and progesterone to protect the body form conditions such as osteoporosis and heart disease and to address the imbalance of hormones that the menopause causes. Taking isoflavones reverses this process and may do more harm than good.
c) Since dong quai is a fairly slow growing plant, taking three years to reach maturity, and the demand for it is growing, it runs the risk of becoming the modern day silphion, a cure it all that was used until extinction. There would have to be a sustainable crop initiated to cope with the demand. The production of dong quai for use as a non-prescription medicine may have adverse effects on those taking it.
As it would be a herbal medicine there would be no way of ensuring that the effects it had were beneficial to the taker and that they were getting the correct medicine for their symptoms. There may be other health issues that make taking dong quai dangerous and people taking the drug may be putting their lives at risk. As it is an abortifacient women who mistake pregnancy for the menopause will be endangering the life of their foetus. To address this problem it may be necessary to make products containing dong quai into prescription medicines or to carry out research into the effects dong quai has through clinical trials and make the packaging of dong quai products state the side effects and risk involved in taking it. Education through the media or medical practitioners for women who may be thinking of taking dong quai may make them seek further advice on what to take for their symptoms and enable them to be monitored throughout their treatment to ensure there are no dangerous side effects.ReferencesThe Open University (2007) S250 Medicinal Plants, Topic 4, Milton Keynes, The Open University.