LEAD
Lead is a highly poisonous metal and can affect almost every organ in the body and the nervous system. It is a naturally occurring element found, due to human activity, in all parts of our environment. People can be exposed to lead through inhalation, ingestion, and to a lesser extent, dermal contact. Because they absorb more lead than adults and because their brains and nervous systems are still developing, children under 6 and the developing fetus are most susceptible to lead exposure. The most common source of lead exposure is the ingestion of old lead paint. The U.S. Environmental Protection Agency (EPA) estimates that lead in drinking water can be 20% or more of a person’s lead exposure. Lead can enter drinking water when plumbing materials that contain lead corrode, especially where the water has high acidity or low mineral content that corrodes pipes and fixtures. Lead pipes, faucets, and fixtures are the most common sources of lead in drinking water. In homes with lead pipes that connect the home to the water main, also known as lead services lines, these pipes are typically the most significant source of lead in the water. Lead pipes are more likely to be found in older cities and homes built before 1986. Among homes without lead service lines, the most common problem is with brass or chrome-plated brass faucets and plumbing with lead solder. Lead can enter drinking water when service lines, pipes in the home, other plumbing fixtures, or solder that contain lead corrode. Older homes, especially those built before 1986, are more likely to have lead service lines, fixtures, and solder. However, even newer “lead-free” fixtures could contain up to eight percent lead until 2013.
Lead, unlike many other drinking water contaminants, is usually not present in the drinking water source, but rather results from the distribution system or on-site plumbing itself. Lead gets into the water at the tap when water with “corrosive” chemistry comes into contact with lead in pipes, fixtures, and solders. The Safe Drinking Water Act (SDWA) has reduced the maximum allowable lead content -- that is, content that is considered "lead-free" -- to be a weighted average of 0.25 percent calculated across the wetted surfaces of pipes, pipe fittings, plumbing fittings, and fixtures and 0.2 percent for solder and flux.
Corrosion is the dissolving or wearing away of metal caused by a chemical reaction between water and your plumbing. Several factors are involved in the extent to which lead enters the water, including:
• The chemistry of the water (acidity and alkalinity) and the types and amounts of minerals in the water
• The amount of lead it comes into contact with
• The temperature of the water
• The amount of wear in the pipes
• How long the water stays in pipes
• The presence of protective scales or coatings inside the plumbing materials.
Health Effects
• Children under six are most at risk from lead poisoning. Children will absorb 30-75% of the lead they ingest. Estimates are, on average, lead in drinking water contributes between 10 and 20 percent of total lead exposure in young children.
• Exposure to high levels of lead can cause severe damage to the brain, blood and kidneys.
• Even low levels of lead exposure have been found to permanently reduce cognitive ability and cause hyperactivity in children.
• Long term exposure can cause reproductive harm and infertility.
• Pregnant women are susceptible to lead, as exposure can harm the fetus, reducing growth rates and causing premature birth and/or miscarriage.
Environmental Effects of Lead
Not only leaded gasoline causes lead concentrations in the environment to rise. Other human activities, such as fuel combustion, industrial processes, and solid waste combustion, also contribute. Lead can end up in water and soils through corrosion of leaded pipelines in a water transporting system and through corrosion of leaded paints. It cannot be broken down; it can only convert into other forms. Lead accumulates in the bodies of water organisms and soil organisms. These will experience health effects from lead poisoning. Health effects on shellfish can take place even when only very small concentrations of lead are present. The body functions of phytoplankton can be disturbed when lead interferes. Phytoplankton is an important source of oxygen production in seas and many larger sea animals eat it. That is why we now begin to wonder whether lead pollution can influence global balance. Soil functions are disturbed by lead intervention, especially near highways and farmlands, where extreme concentrations may be present. Soil organisms than suffer from lead poisoning, too. Lead is a particularly dangerous chemical, as it can accumulate in individual organisms, but also entire food chains.
Treatment Options
Lead is a relatively unreactive post-transition metal. Its weak metallic character is illustrated by its amphoteric nature; lead and lead oxides react with acids and bases, and it tends to form covalent bonds. Compounds of lead are usually found in the +2 oxidation state rather than the +4 state common with lighter members of the carbon group. Lead is a relatively unreactive post-transition metal. Its weak metallic character is illustrated by its amphoteric nature; lead and lead oxides react with acids and bases, and it tends to form covalent bonds. Compounds of lead are usually found in the +2 oxidation state rather than the Lead is a soft metal that has known many applications over the years. It has been used widely since 5000 BC for application in metal products, cables, and pipelines, but also in paints and pesticides. Lead is one out of four metals that have the most damaging effects on human health. It can enter the human body through the uptake of food (65%), water (20%), and air (15%).
Lead can enter (drinking) water through the corrosion of pipes. This is more likely to happen when the water is slightly acidic. That is why public water treatment systems are now required to carry out pH-adjustments in water that will serve drinking purposes. For as far as we know, lead fulfils no essential function in the human body, it can merely do harm after uptake from food, air or water. Lead can cause several unwanted effects, such as: • Disruption of the biosynthesis of hemoglobin and anemia • A rise in blood pressure • Kidney damage • Miscarriages and subtle abortions • Disruption of nervous systems • Brain damage • Declined fertility of men through sperm damage • Diminished learning abilities of children • Behavioral disruptions of children, such as aggression, impulsive behavior and hyperactivity Lead can enter a fetus through the placenta of the mother. Because of this it can cause serious damage to the nervous system and the brains of unborn children. The treatment methods of lead ions have ion exchange (chemical precipitation ; biosorption , infiltration, electrolysis, membrane separation , and so on. At present, nano-iron has been used in heavy metal pollution of groundwater, soil and other governance. Compared with the traditional methods of heavy metal treatment, the removal efficiency of nano-iron is high and the time required is short. These advantages make nano-iron more and more important in removing heavy metal pollution. The nano-iron has the advantages of small particle size (<100 nm), large specific surface area and high reactivity which is easily oxidized or spontaneous in the air. Reverse Osmosis also remove 90-95% of lead impurities. Ion Exchange softeners also remove lead. In order to particularly remove and avoid the accumulation of Lead in water we have to focus on the POU/POE products. since most lead in drinking water is the result of corrosion in the water distribution and home plumbing system. We have to choose for corrosion free equipment having long life. Also monitoring of the water should be done periodically at POE & POU to have an idea of increase in lead content due to corrosive pipelines. The pipelines and faucets should be replaced as per performance capabilities based on results from competent equipment validation testing for the specific contaminant to be reduced.
References
Treatment of lead contaminated water using synthesized nano-iron supported with bentonite/graphene oxide, Arabian Journal of Chemistry. Volume 13, Issue 1, January 2020, Pages 3474-3483
https://www.sciencedirect.com/science/article/pii/S1878535218302491#b0205
https://www.espwaterproducts.com/how-to-remove-lead-from-water/#:~:text=The%20CDC%20suggests%20two%20ways,99.1%25%20of%20lead%20in%20water.
US EPA (May 25, 2022). “Basic information about lead in drinking water”. Retrieved from
https://www.epa.gov/ground-water-and-drinking-water/basic-information-about-lead-drinking-water
https://cen.acs.org/environment/water/Treatment-lead-drinking-water-evolving/96/i47
https://www.cdc.gov/nceh/lead/prevention/sources/water.htm