Lead (Pb) is the 82nd element in the Periodic Table. This soft, workable metal was widely used in pipes, paints, and fuels for centuries. Unfortunately, lead is highly toxic, and even low concentrations of lead in the blood can result in lifelong health problems. Since this discovery, lead has been removed from domestic products, fuels, and many other chemicals. Despite this, lead contamination is still a significant environmental concern. Keep reading to get to know more about the properties of lead, its uses, and more.
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Jetzt kostenlos anmeldenLead (Pb) is the 82nd element in the Periodic Table. This soft, workable metal was widely used in pipes, paints, and fuels for centuries. Unfortunately, lead is highly toxic, and even low concentrations of lead in the blood can result in lifelong health problems. Since this discovery, lead has been removed from domestic products, fuels, and many other chemicals. Despite this, lead contamination is still a significant environmental concern. Keep reading to get to know more about the properties of lead, its uses, and more.
What is lead?
Lead is a soft post-transitional metal.
Lead has a bright, silvery appearance with a hint of blue. It tarnishes upon contact with moist air.
What is a post-transitional metal? Well, like most metals, post-transitional elements are malleable, ductile and relatively dense. However, their lower melting and boiling points separate these metals from the rest.
Lead occurs naturally within the Earth's crust, often combining with oxygen and sulfur.
Lead's key properties as a metal include:
A low melting point
Workability
Corrosion resistance
Poor electrical conduction
High toxicity
Lead has high toxicity. Even just 5 µg/dL of lead in the bloodstream can cause lead poisoning. Symptoms of lead poisoning include fatigue and pain. In children, it can lead to developmental delays and learning difficulties.
Lead toxicity typically affects the CNS.
CNS refers to the central nervous system, which comprises the brain and spinal cord.
Lead neurotoxicity occurs when lead exposure alters normal CNS activity, causing damage. Symptoms can be immediate or delayed.
Lead is liposoluble, meaning that it can dissolve in fats. This property allows it to enter organs such as the brain and the liver.
Liposolubility isn't lead's only fat-related trait. High levels of lead in the bloodstream can cause an excess of adipose tissue, leading to obesity. The suspected cause is lead-altering gene methylation, affecting genes related to the body's metabolism.
Methylation is the addition of a methyl group (CH3). Its addition can negatively affect how molecules act in the body.
This symptom can even be passed down to unborn children; maternal lead exposure has been associated with a higher intergenerational risk of obesity.
Lead can build up in the bodies of animals, including humans. Over time, this can lead to lead poisoning. Unlike many pollutants, lead is not subject to biomagnification.
Biomagnification is the increasing concentration of a pollutant along the food chain.
Lead is mostly stored in the bones, which reduces the risk of lead transmission to other animals in the food chain.
Lead occurs naturally in soils, at low rates of 10 to 50 mg/kg. Lead tends to accumulate in the upper layers of soil, closest to the surface, where it is held very tightly by particles of clay and organic matter.
Small amounts of lead in the soil can be transferred to plants – but not always. Lead availability to plants depends on how tightly it is held by soil particles and its solubility.
In neutral soils (around pH 6.5), the lead is held tightly by the soil, and it has low solubility. It is not easily taken up by plants.
In acidic soils (around pH 5) lead is held less tightly, and is more soluble, so it can be taken up by plants.
If lead is taken up by plants, it has the potential to be passed to any animals (including humans) who eat the plants.
Don't worry, natural levels of lead do not pose any harm. Only soils contaminated with lead from artificial sources can present a risk.
Lead has been widely used since Roman times due to its corrosion resistance and workability.
Since discovering its toxicity, lead has been discontinued from a range of products:
Pipes (including solders)
Paint and glazes
Insecticides
Hair dyes
Petrol additive
Radiators
When storing or disposing of waste lead, the lead is kept at a high pH to reduce solubility and toxicity.
However, lead is still used in a few products. Despite its toxicity, it has some unique and useful properties.
Car batteries often contain lead. These batteries perform better at lower temperatures than other kinds of battery. Furthermore, they're a cost-effective method for storing enough energy to start a vehicle.
Lead's high density and ability to absorb vibrations make it an excellent shield against harmful radiation. As a result, lead is used in X-ray machines and nuclear reactors.
High density lead linings are commonly used in the storage of corrosive liquids.
Because of lead's widespread use for centuries, lead pollution is a significant environmental problem.
Soils can become contaminated with lead pollution from manufacturing processes, mining, burning materials containing lead, or water runoff. Water itself can become contaminated if it travels through a source of lead, such as pipes.
A notable domestic source of lead pollution is paint chips from old lead-based paint. Furthermore, some countries use lead in traditional medicine and cosmetics, such as Kohl.
Kohl is a dark-coloured eye cosmetic, often made by grinding galena (lead sulfide).
Once the environment has experienced lead pollution and contamination, it can have a range of negative effects on plants, animals, and humans.
Excess lead in the soil can cause a number of toxicity symptoms in plants, including stunted growth and chlorosis.
Chlorosis is the loss of a plant's green colouration, generally caused by micronutrient deficiencies.
Lead can inhibit photosynthesis, disrupt water and mineral balances, impact seedling development, and alter the plant's hormones.
At very high lead concentrations of 10000 to 40000 mg/kg, lead can affect the soil community, killing bacteria and fungi. Many of these microorganisms have mutualistic relationships with plants.
A symbiotic relationship is a close ecological relationship between individuals of two different species. In a mutualistic symbiotic relationship, both species benefit.
Mycorrhizal fungi form mutualistic relationships with plants. The fungi increase the root area, helping plants to access essential nutrients and vitamins. In return, plants provide the fungi with carbohydrates.
If lead poisoning disrupts the soil community, it can have severe effects on plant growth and nutrient cycling.
Lead can enter the human body by consuming contaminated food and water, or inhaling dust or fumes that contain lead. Once in the body, it's stored in the bones and blood, giving rise to a range of unpleasant symptoms. Large doses of lead can cause pain, weakness, headaches, memory loss, anaemia, organ damage, and even death.
Lead exposure can cause miscarriage and stillbirths in pregnant women. Alternatively, it can cross the placenta and cause damage to the unborn baby's nervous system.
Children are at significant risk of irreversible long-term effects of lead poisoning. In particular, lead influences brain development and reduces IQ and attention span, whilst increasing antisocial behaviour and risk of psychiatric problems in later life.
It's estimated that 62.5% of unknown development and intellectual disabilities were caused by lead exposure.
Additionally, children are more likely to ingest lead than adults. Young children regularly put objects in their mouth. Eating sweet-tasting lead paint chips is a common cause of lead poisoning in children.
1 in 3 children worldwide have significant levels of lead poisoning, causing 1 million deaths annually. Furthermore, the intellectual disabilities it causes has led to an estimated $1 trillion loss of income for low and middle income countries. That's approximately 6% of their GDP. Scientists have also observed a link between lead exposure and violent crime.
The charity Lead Exposure Elimination Project (LEEP) aims to reduce lead poisoning around the globe. 59% of countries have no regulation on lead paint, so LEEP is pushing for regulations to restrict the production, importation, and sales of leaded petrol and paint. The charity focus on targeted research, government advocacy, industry outreach, and follow-up studies.
I hope that this article has explained what lead is and why it poses a risk for you. This highly toxic metal can contaminate the environment, leading to lead poisoning if ingested. Lead poisoning is a particular problem for children, who may experience irreversible health and developmental problems.
1. Dr Lucia Coulter, Medicine, nonprofit entrepreneurship, and lead, Lead Exposure Elimination Project, 2022
2. Guoying Wang, Association Between Maternal Exposure to Lead, Maternal Folate Status, and Intergenerational Risk of Childhood Overweight and Obesity, JAMA Network Open, 2019
3. Honglin Sun, Lead Exposure Induces Weight Gain in Adult Rats, Accompanied by DNA Hypermethylation, PLoS One, 2017
4. K. M. Wade, Lead, PlantProbs, 2019
5. Nuclear-Power, Lead – Melting Point – Boiling Point, 2021
6. Richard Stehouwer, Lead in Residential Soils: Sources, Testing, and Reducing Exposure,
Penn State Extension, 2010
7. Subhendu Datta, Influence of some abiotic environmental factors on acute toxicity of inorganic lead to Cyprinus carpio var Communis (Linn.) and Catla catla (Ham.) in simulated toxic aquatic environment, Toxicological & Environmental Chemistry, 2003
8. World Health Organisation, Lead poisoning, 2021
Lead is a soft, grey, post-transitional metal.
Lead pollution in the environment can be prevented by removing and disposing of potential contaminants such as old pipes or lead-based paint.
Lead enters the environment by manufacturing processes, mining, burning lead-based materials, or water runoff.
Lead in water can contaminate soils, affecting plants and soil microbial communities.
Lead is used in car batteries, diving weight belts, storing corrosive liquids, radiation protection, and some solders.
Lead’s physical properties are a low melting point, workability, corrosion resistance, poor electrical conduction, and high toxicity.
What is lead?
Lead is a soft post-transitional metal.
What is a major property of post-transitional metals?
Post-transitional metals have lower melting and boiling points than other metals.
When does lead neurotoxicity occur?
Lead neurotoxicity occurs when lead exposure alters normal CNS activity, causing damage.
Define liposoluble.
If a substance is liposoluble, it can dissolve in fats.
Where does lead accumulate in the body?
Lead accumulates in the bones.
Lead cannot be taken up by plants in acidic soils.
False
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