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  • Mckenzie Bagayas

Drinking-Water Contaminant in Focus: Lead

Since the 70s, people have recognized the deadly effects of lead. Although there are laws in place to regulate the usage of lead, there are still products that may contain a significant amount of this chemical. Items like car batteries, cosmetics, pieces of jewelry, toys, ceramics, and canned goods contain lead. Unfortunately, so does our drinking water.


How lead gets into our drinking water

Most of the lead that is present in water comes from the plumbing materials. Although laws have been strict regarding lead usage in plumbing since the 80s, some of the pipes and fixtures that are still present today predate the laws. So yes, there is still a huge possibility that the pipes, faucets, and fixtures in your home may contain some lead. New fixtures, faucets, and pipes aren’t excluded from the lead problem. There are some of them that use lead as a solder.


Now when corrosion occurs in these lead-containing plumbings, the lead would leech into the drinking water. There are a number of factors that would affect how much lead gets mixed into the water:

  • The more acidic the water, the more it could corrode the lead-containing plumbings, the more lead would be present in the water.

  • Oxygen is somewhat corrosive to metal. The more dissolved oxygen is present in the water, the higher the lead content would be.

  • Depending on the type and the number of minerals present in the water; the water could act like a galvanic cell that could corrode the lead-containing plumbings.

  • The amount of lead that comes into contact with the water is also a huge factor. Naturally, if the plumbing has lead only in its solder; then it would impart less lead into the water than let’s say an entire pipe that is made out of lead.

  • The temperature of the water also matters, the warmer the water is, the more it could corrode the metal.

  • Also if the pipes have a lot of wear then there would be more surface area for the water to come into contact with the lead-containing plumbing which would mean more lead leaching.

  • How long the water would come into contact with the lead-containing plumbing also matters. The longer the two would remain in contact, the more the plumbing can be corroded.

  • If your water is ‘hard’ or contains a lot of dissolved solids, it is prone to forming scales in the plumbing. When plumbing scales are formed, they would prohibit contact between the water and the lead-containing plumbing. When there is no contact between the two, corrosion doesn’t happen and the leaching of lead into the water does not occur as well.

  • Some lead-containing plumbing possesses a protective coating on the inside. This could discourage corrosion as well.



Lead’s Safe Levels

According to the SDWA or the Safe Drinking Water Act, the maximum allowable lead content of the pipes’, faucets’, or fixtures’ surface that comes into contact with the water must be, on average, 0.25 percent or lower. According to the Environmental Protection Agency or EPA, safe drinking water contains 15 micrograms of lead per liter of water or less.


When it comes to children, the lead’s safe levels may not apply. So far, there has been no scientific data regarding ‘safe lead levels for children’. So for now, we should assume that even a tiny amount of lead in our water can be harmful to our children.


Human skin does not absorb lead

It is quite concerning to have lead in your tap water. However, it is actually okay to bathe in water that contains lead. This heavy metal can only be absorbed by your body if you either inhale it or ingest it. Lead present in water is not absorbed by the skin.


Negative Health Effects of Lead

In Children

The negative health effects of lead on children are especially worth mentioning, as this heavy metal isn’t only bad for their health but also for their academics and their future career.


When children are exposed to lead and their blood lead levels or BLLs reach 5 micrograms per deciliter or more, adverse health effects would occur. The most common adverse health effects include:

  • Attention-related behavioral problems,

  • Decreased cognitive performance

  • Greater incidence of problem behaviors.

Other negative health effects include:

  • Slowed growth

  • Hearing problems

  • Anemia

It is important to note that these other effects could appear even if lead exposure is significantly low.


Children are exposed to lead more frequently than you might think. In the United States alone, 2.6% of children between the ages of 2 to 4 had a blood lead concentration of 5 micrograms per deciliter or more. In some of these cases, the child would experience seizures, coma, and even death.


In Pregnant Women

Lead is dangerous not only to the expectant mother but also to the baby that they are carrying. In adults, lead can build up in the bones along with calcium over time. For pregnant women, the lead that is stored in their bones is released along with the calcium to form the bones of the fetus. This process is more prevalent in mothers who don’t have enough dietary calcium. This means that if the mother doesn’t take enough calcium and is exposed to a significant amount of lead, then their developing fetus would be exposed to harmful levels of lead. When this happens, there are numerous health consequences which include:

  • There is sufficient data to link reduced fetal growth and or low birth weight to the expectant mothers’ blood lead levels when it reaches or exceeds 5 micrograms per deciliter

  • The chances of premature birth are greater in those who are exposed to lead

  • Blood lead levels that reach or exceed 10 micrograms per deciliter have been associated with increased blood pressure and hypertension. Moreover, pregnant women are more at risk of developing eclampsia and pre-eclampsia.

Newborns aren’t safe from their mothers’ blood lead levels for this heavy metal can also be transmitted through breast milk. It is of utmost importance to be vigilant about the mother and the baby’s lead exposure.


In Adults

Adults are more resistant to the negative effects of lead. However, there is a certain exposure threshold that should be followed so that the adverse effects are avoided. Even if your drinking water is considered ‘lead-free’, remember that there are other ways that you’ll be exposed to lead. So a more superior indicator of lead safety must be based on the Blood Lead Levels or BLL. So far, research has shown that negative health effects would only start to appear if a person has around 5 micrograms of lead per deciliter of their blood, in other words, if they have a BLL of 5 micrograms per deciliter. Harmful effects of lead include:

  • Cardiovascular diseases increased blood pressure, increased the chance of developing hypertension

  • Renal disease

  • Reproductive problems in both men and women


Neurological Effects

The neurological effects of lead exposure is well documented and well studied. The problem with lead is that it acts like calcium but it binds to the protein kinase C or PKC receptor more strongly than calcium. When lead binds to the PKC it alters neurotransmitter release. This alteration in neurotransmitter release could then lead to harmful gene expression and protein synthesis changes. This is the physiological basis as to how lead exerts its neurological effects.


The neurological effects of lead is insidious, often taking many years for it to appear. The fact that this heavy metal may exert its neurological effects even at levels below 10 micrograms per deciliter, makes this pollutant even scarier. Neurological symptoms of lead exposure may appear at a time when it's already too late to do anything about it. The stunting of cognitive development in children is not apparent, not until the mental demands of school would increase, which is around late middle school. Although there are ways to mitigate this negative effect, it isn’t easy to do and the child’s academics would have been highly affected.


Serious exposure to Lead leading to Blood Lead Levels of 70 - 80 micrograms per deciliter can cause encephalopathy in children with lasting neurological and behavioral damage. Encephalopathy could also occur in adults but the BLL must reach 460 micrograms per deciliter for it to happen.


Renal Effects

Since the kidney filters and removes toxins from the blood, it is sensitive to the amount of lead present in it. For quite some time, people knew that lead is harmful to our nephrons. At a certain Blood Lead Level, lead nephrotoxicity would be observed and it is characterized by proximal tubular nephropathy, glomerular sclerosis, and interstitial fibrosis. Currently, there’s not enough information regarding the lowest blood lead level that can negatively affect the kidneys. However, there are a few studies that allude to this information. One population-based study indicated that a BLL that is less than 5 micrograms per deciliter is linked to negative effects on kidney function that leads to increased risk of chronic kidney disease and a reduction in glomerular filtration rate and creatinine clearance. Moreover, an increase in blood pressure and risk of developing hypertension is observed which are conditions that could also damage the kidney. In a different study that had occupational workers as participants, it was indicated that a BLL that is greater than 60 micrograms per deciliter resulted in negative renal effects.


Hematological Effects

Lead is also especially harmful to our Hematopoietic stem cells, our stem cells that mature into blood cells. Specifically, those that belong to the red blood cell line. Cells belonging to this line are destined to create hemoglobin as it matures. The problem with lead is that it can interfere with the enzymes that are needed in the creation of hemoglobin. To be more specific, lead interferes with the enzyme that helps insert the iron into the hemoglobin which could then lead to a decrease in the formation of hemoglobin. Fortunately, there is an established exposure threshold for lead. The Environmental Protection Agency stated that for adults BLL should be less than 50 micrograms per deciliter for adults and 40 micrograms per deciliter for children. However, some scientific research papers lowered the threshold to 25 micrograms per deciliter for children. Despite lead’s effect on our hematopoietic stem cells, lead-induced anemia is uncommon in adults, it is more common among youngsters.


Endocrine Effects

Vitamin D plays a huge role in cell growth, maturation, and tooth and bone development. Lead prevents the conversion of vitamin D into its active and hormonal form. Once this happens, vitamin D cannot carry out its role. This is especially harmful to developing children as they are undergoing rapid growth. Fortunately, the adverse effects of lead on growth occur at a higher threshold of 62 micrograms per deciliter and it can be prevented by ensuring that the child gets enough calcium, phosphorus, and vitamin D.



How to Avoid Exposure

Parents should be responsible for keeping their children safe from exposure. Wash their hands thoroughly when they are playing in the ground as the dust or soil might be contaminated with lead. Wash their toys as well for they could be covered in soil or dust that contains lead. Teach them not to put their hands in their mouth when they are playing in the ground. If they’re still to young to be taught, don’t allow them to play on the ground.


Clean dusty surfaces in your house and remove your shoes before entering the house. Again, dust or soil could contain lead.


If your plumbing is a bit dated, you need to replace them with plumbing that contains less lead. If that is not possible, a temporary solution would be to run your tap until the water is cold. You could also use filters to remove lead in the water. Make sure to get the reverse osmosis and or activated carbon filters as these are the only filters that effectively remove lead from water.


Feed your children with foods that are rich in calcium, vitamin C, and iron. These vitamins and minerals have been shown to compete with lead absorption. If they are taken in sufficient amounts, they prevent the absorption of lead.


Do not use lead-based paint, if your home has lead-based paint, be vigilant when the paint starts to peel. It is better to leave lead-paint alone when it is not peeling or cracking. But when it starts to come off, do not sand the surface to remove them as this will generate dust particles. Instead, hire someone who specializes in the safe removal of lead paints.


Sources:

https://www.epa.gov/ground-water-and-drinking-water/basic-information-about-lead-drinking-water

https://www.atsdr.cdc.gov/csem/csem.asp?csem=34&po=10

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4961898/