Lead pollution: How do we solve plumbosolvency?

5 years ago

The linkage between the chemical element of lead and water streams all the way back to the Roman dynasty during the Earth’s classical era in history. The Latin word for lead is plumbum, which is where the elemental symbol for lead, Pb, originates, as well as the English word; plumbing. The extreme dangers of ingesting lead substances are certainly no modern ground-breaking scientific discovery ho. The Romans often used lead containers to store their wine, especially when preparing a sweetener additive. As an alcohol, wine obviously contains its share of ethanol, molecules of ethanol oxidised by the helping hand of the atmosphere will result in molecules of acetic acid. This is the very same reason soured or dated wine holds an obvious and pungent stench of vinegar. A combination of these factors resulted in lead acetate. This by-product would coat itself on the inner walls of the container, and was commonly used as a sweetener for its sugary-tasting capabilities, which often resulted in terrible abdominal pain. Historians have often suggested the overzealous use of lead played a major part, among other factors, in the inevitable demise of the once great civilisation. [1]

What exactly does the Romans and their particular fondness of lead-enriched wine have to do with us today you are probably wondering? To sum up the answer to that question in one word – plumbosolvency. To be precise, plumbosolvency is the ability of a liquid material to partially dissolve aging lead interfaces; the liquid material in this case is water. Playing the role of the solvent, water will degrade lead pipes over time and dissolve atoms of lead cations, which holds dangerous repercussions. The conditions where plumbosolvency occurs the most evidently are dependent on the age of the lead pipe system, the pH of the water being passed through, the type of water, and finally the temperature of the water and how long it was left stagnate in the pipe. The greater the age of the lead pipe, the more likely it will degrade to disassociate lead ions into the water. Water holding a pH value typical of an acidic substance has the ability to leach lead ions into the water being passed through the pipes. Water at a lower pH holds the characteristics of being corrosive and soft. The type of water being passed through is also a deciding factor in the level plumbosolvency occurring. Soft water will dissolve lead to a greater degree in comparison to hard water. The difference being hard water contains dissolved calcium and magnesium divalent cations, and soft water is naturally more inclined to be acidic. In a sense, soft water tries to harden itself by dissolving lead ions, but with a more toxic metal. The warmer the temperature and the longer the time upon which the water is in contact with the lead surface is deciding factor of the extent of plumbosolvency occurring_. [2]

The sinister implications of upsetting the balance of the previous discussed factors, which contribute to plumbosolvency, is best exemplified by the water crisis in Flint, Michigan in the US from 2014 until present. A water safety crisis sparked from a penny-pinching action to take a fatal shortcut to reduce water treatment costs where the initial source of water was Lake Huron and the Detroit River. The shortcut taken was to change the source to the Flint River, which was much more corrosive and poorly treated. This upset the balance of factors causing plumbosolvency, the corrosive river water, which also contained other contaminants due to poor water treatment, leached lead from the old pipes. In 2015, a staggering 5% of the children screened for blood-lead levels were over the limit. An action carried out purely for the benefit of the governing administration’s budget rather than the benefit of the safety of the people saw up to 12000 children and 100000 people overall effected through elevated lead exposure. Due to the poorly treated water source, the presence of exterior contaminants resulted in the deaths of 12 people from Legionnaire’s diseases. [3]

The implications of lead poisoning are unfortunately so extensive they cover almost all parts of the human anatomy, and what is even more sinister is that the target victims are the most vulnerable in society; pregnant women and children. When we are exposed to lead, the route to which the poisonous chemical ventures to enter our bodies is primarily through inhalation or through means of ingestion, but in terms of lead in water the most obvious route of entry is through ingesting the lead polluted water. Now that we have an understanding into the initial route lead takes to enter the body, it is then distributed to all organs throughout the body. Built up lead in the bones and teeth of a pregnant woman allows a pathway for lead to enter the bloodstream and hence be in contact with the foetus, which unfortunately can result in miscarriage, stillbirth, premature birth and low birth weight. When it comes to children the brain is unfortunately the most vulnerable to attack by ingested lead. Lead can enter the brain of a children as a result of the malfunction of the plasma membrane calcium ATPase transport protein, or PMCA. PMCA in a cell acts as a calcium ion regulator by removing the excess amount of calcium present into the particular extracellular medium which in this case is the brain. This release of excess calcium isn’t usually a problem as calcium holds no fatally toxic effects, whereas in the event of a malfunction where the transport protein mistakes lead for calcium it is an extremely worrying issue. [4] Lead poisoning occurs from the accumulation of lead built up in the body. In the case of the child’s brain, lead degenerates the myelin coatings of neurons, which act as electrical insulators and are responsible for quickly sending nervous messages. This slows down and interferes with the efficiency of neurotransmitters which in turn slows down the processing of information from the brain to the various functions. [5] This is just a single example of the effect of lead on the human body. Lead built up in a child’s brain can have staggering results, lead poisoning stunts the mental development of children by reducing the capacity to attain information by reducing the intelligence quotient (IQ) and is believed to have a strong hand in promoting mental disorders such as attention deficient disorder (ADD), attention deficient hyperactivity disorder (ADHD). [6] This in turn promotes antisocial behaviour. Taking these factors into consideration, it cannot be denied lead greatly reduces the chances of our children reaching their true potential, be it right from the off to experiencing lead exposure during their preadolescence years.

Now that a basis of understanding of the toxic risks of ingesting lead polluted water has been established, it is now appropriate to discuss the most commonly used techniques to reduce and hopefully prevent plumbosolvency from occurring and affecting our homes. The two most common solutions applied to counteract plumbosolvency are pH adjustment at water treatment plants, and by orthophosphate dosing. The onus of responsibility undoubtedly rests on the shoulders of Irish Water and by extension the government. It is the responsibility of Irish Water to ensure these measures are carried out for the safety of our children and ourselves. In a 2016 mitigation plan established to counteract lead pollution, Irish Water have outlined their plans to increase the optimisation of pH adjustment and add orthophosphate treatment to water treatment plants. In November 2016, Irish Water installed orthophosphate treatment measures to the water treatment plant in Clareville, Co. Limerick. This is an area associated with seeing a 5% failure of properties in lead pollution readings. Since installing these combative measures, this failure percentage has dropped to 2%. Irish Water also installed orthophosphate treatment measures in Hacketstown, Co. Carlow in 2016. These counteractive measures carried out are inspiring but a greater effort is essential, Irish Water must increase their lackadaisical approach to combating this grave issue. [9][15][16]

As previously discussed, a deciding factor on the extent of lead pollution of water occurs according to the pH of the water in question. In drinking water treatment plants, one of the closing steps of the process looks at pH adjustment, whereby equal amounts of acid and base are added to neutralise the pH of the water. If the pH is too high, as in above the range of 6 – 8, sulphuric acid (H₂SO₄) is added to neutralise the alkalinity of the water. Alternatively, if the pH is too low, as in below the range of 6 – 8, calcium hydroxide (Ca(OH)₂) is added to neutralise the acidity of the water.[7] The second and most widely used action to combat lead pollution of water is orthophosphate dosing. This is an extra step in water treatment plants where phosphate containing chemicals such as phosphoric acid (H₃PO₄) or monosodium phosphate (NaH₂PO₄) is added in amounts of 1.5 mg/L. The mode of action to which the orthophosphate reduces plumbosolvency is by forming an orthophosphate coating within the inside of the lead pipes. It takes up to 12 months for this coating to fully form and work effectively, it is then maintained by the addition of 0.5 mg/L of the relevant phosphate containing chemical at the treatment plant. The utilisation of orthophosphate dosing has been noted as being successful in areas such as the USA, UK, Canada and mainland Europe. [8]

The worry associated with this action is the increase in concentration of phosphate in our water. Phosphates can be toxic for the environment and potentially be detrimental to aquatic organisms. The increase of phosphorus containing chemicals in sewage can seep into environmental water systems containing aquatic organisms such as rivers and lakes. Phosphorus rich water acts as an extremely nutritious ingredient and consequently sees an exponential increase in algae growth; these algae blooms harvest the dissolved oxygen and results in the asphyxiation of fish and other aquatic life. Phosphate toxicity in humans can result in weaken bones and muscle tissue by reducing calcium levels present. Excessive amounts of phosphate in the body can result in calcium phosphate forming, which in turn increases calcium levels to an excessive proportion and thereby weakens bones and muscles. This can then have a domino effect by seeing rhabdomyolysis occurring, which is the breakdown of muscle tissue. This breakdown sees the release of excessive amounts of myoglobin in the bloodstream, which thereby can result in kidney failure due to the excessive excretion demands. [18]

It is widely accepted that the most effective method of fully solving the lead pipe problem we face today is the full replacement of all lead pipes still in use. Two obvious issues arise with this however, the first being knowing where to implement all the lead pipe replacements that are required and the second being the cost factor. The likelihood of the relevant authorities knowing where exactly the location of all the lead pipes that need to be replaced is slim. The only realistic way of determining the location is by the constant gathering of water samples all around the country, even if there shows no sign of lead it would be wise to continue vigilance, as plumbosolvency may occur at any time given the correct conditions are met. The issue of the cost of replacing a pipe becomes relevant on the exact location of the pipe, as in if the pipe is found beneath a main road or not within a resident’s property the relevant authorities are charged with the replacement. However, if the pipe in question is found to be part of the domain of the resident, it is up to the individual to pay for the replacement.[9][10] This can be worrying as some may decide against forking out a sum of money on top of the already substantial bills the resident is expected to pay. In an act to help alleviate this issue, the government have grants in place where households who have an annual income of €50000 or less can be granted up to €4000, and households who have an annual income of between €50000 and €70000 can be granted up to €2500.[10] In a recent Irish Times report, it was indicative of areas across Dublin and other areas in the country, which measured lead concentrations in the water of up to 15 times the allowed limit. The report was both educational and shocking in its content, a test sample taken in close proximity to Sutton train station measured 15 times above the limit set by the EU of 10 ppb, or 10 µg/L. In the recent past, other areas in Dublin, such as Coolock measured 12 times above the limit, others such as Terenure, Cabra, Sandymount, Beaumont, Drumcondra and Phibsborough have all measured above the limit. [11] The vast majority of these cases are due to old houses with old pipe work. It is worth noting the latter three districts all are synonymous with having beautiful Edwardian era style red-brick houses built by Alexander Strain in the earlier part of the previous century. Houses that undoubtedly used lead piping when they were in their creation. The EU have made their intentions clear to cut the allowed limit in half to a limit of 5 ppb, as there is no safe amount of lead in the body. This raises the concern for how many more areas across the country will test over the limit.[12]

To finish up on giving food for thought on the issue of lead pollution in water, it is worth considering that prior to Ireland’s entry into the EEC in 1973, which is now the EU, our economy was primarily ran on an agricultural in-house model with our only major trade partner being Britain. It is also worth considering that Ireland is an internationally renowned lead mining province, with zinc-lead ores in Lisheen and Galmoy, whose combined efforts made Ireland the largest producer of zinc in Europe and the second largest producer of lead at one point in our history, the latter mine is now closed however. [13] As discussed the dangers of lead poisoning were chartered back as far as the Roman times, but in more modern times the first documented study of the dangers of lead paint on children was back in 1897 in Australia. In other cases, countries such as France, Belgium and Austria all banned the use of lead based paint in 1909 on the back of knowing the toxic consequences at risk. [14] As our economy ran on an in-house model where we primarily used our own resources, one can only wonder why we still used lead pipes in the creation of our homes up until the mid-70’s. Perhaps taking short-cuts by choosing the cheaper option in order to make money is more important than the health of our children and our children’s children? How many years until our children are fully safe from lead poisoning?

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Lead pollution: How do we solve plumbosolvency?

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