(ii) Sources of the metal and/or its compounds displaying toxicity.

Sources of lead

The main sources of lead entering an ecosystem are atmospheric lead (primarily from automobile emissions) ,paint chips, used ammunition, fertilizers and pesticides, as well as lead-acid batteries or other industrial products.

Lead in our daily lives

 

Lead compounds displaying toxicity:

Lead (II) acetate, Lead (II) oxide, Lead (II) nitrate, colloidal Lead (II) hydroxide, colloidal Lead (II) oxy chloride, colloidal Lead (II) oxy carbonate and Lead (II) carbonate. 

Lead (II) acetate

Lead (II) oxide

 
 

(iii) Describe briefly why / how the metal and/or its compounds are harmful to organisms and/or environment.

How lead is harmful to humans?

 Lead affects almost every organ system but mostly the central nervous system, particularly the developing brain.
  Lead ion has highly disruptive properties. It replaces other metals (e.g., zinc, calcium and iron) in reactions.
  Lead interferes with the proteins by displacing other metals in the molecules. This changes the shape of the protein molecule.
  Damaged proteins lead to disruption of cellular function and cell death. Lead ²⁺ ions can substitute for calcium ions or displace calcium in the reactions that transmit electrical impulses in the brain.
There is also no means of removing metal ions from the body, so they tend to accumulate.

The symptoms of lead poisoning may include:

• Abdominal pain and cramping
• Constipation
• Difficulty sleeping
• Irritability
• Loss of developmental skills (in young children)
• Reduced sensations

Very high levels of lead may cause vomiting, muscle weakness, seizures, or coma.

Consequences of Lead poisoning

 How is lead harmful to other organisms and the environment

  Lead can remain in the environment as dust indefinitely.

  It can enter the environment through mining practices, steel industry, crop enhancers, improperly disposed of batteries, or improperly stored metal parts that leech into the surroundings.

  Atmospheric lead is deposited in vegetation, ground and water surfaces. In certain chemical environ­ments it will be transformed to increase its solubility (e.g., the formations of lead sulfate in soils),

  Lead in vegetation and animal surfaces can prevent the processes that purifies the calcium pool in animals and decomposer organisms.

Lead in the environment

Effects of lead on soil

  Lead accumulates in the soil, especially soil with a high organic content 

Lead displaces other metals in the soil and become more soluble, thus is more readily taken up by plants.

  Soils near highways, freeways, and smelting facilities have higher levels of lead because of exposure to lead dust.

Effects of lead on plants

  Plants on land tend to absorb lead from the soil and retain most of this in their roots. 

Lead coats the surface of the leaf and reduces the amount of light reaching it. lead can affect population genetics.

Effects of lead on micro-organisms

  Evidence also suggests that micro-organisms can make lead more soluble and hence more easily absorbed by plants.

Effects of lead on animals

  Aquatic organisms take up inorganic and organic lead through a transfer of lead from water and sediments

Done by:

Lim Li 

(iv) State what can be done about the problems or social issues raised, such as treatment for poisoning, or government intervention/regulation.

  Lead poisoning can be identified by undergoing a blood lead test or urine test. Over 25 micrograms per decilitre (mcg/dL) can put one’s life at risk.

  Treatment for lead poisoning varies depending on the amount of lead in the blood. Small amounts can often be treated with the reduction of lead exposure and as the body naturally eliminates the lead, the level of lead in the blood will fall.

  For severe lead poisoning however, the patient will need to undergo Chelation therapy or EDTA therapy. In Chelation therapy, the patient takes a medication that binds with the lead so that lead can be removed from the body via excretion.Common drugs used for chelation therapy includes Penicillamine, Dimercaprol and Dimercaptosuccinc acid. However, this can cause side effects like skin irritation, fever, headache and nausea.

  Under EDTA therapy, the Doctors treat the blood with a chemical called ethylenediaminetetraacetic acid (EDTA). EDTA therapy is classified under Chelation therapy but EDTA therapy is used for patients suffering from more severe cases of lead poisoning. The side effects from this therapy can include abdominal pain,fatigue and make existing effects from asthma, diabetes and hepatitis even worse.

Regulations and Measures can also be taken by the government to minimize the risks of lead poisoning. Measures in every country usually revolve around:

• Environmental standards that remove lead from petrol/gasoline, paint and plumbing.
• Enforcement of occupational health standards.
• Surveillance of potentially exposed population groups, especially the vulnerable ones (children, pregnant women, workers).
• Water treatment.
• Removing lead solder from food cans.

Examples of Regulations:

  Ban on the use of lead pipes for drinking water in new installations, and the phasing out of lead-based petrol. (UK)

  Encapsulation of lead painted surfaces with materials approved as an encapsulate of lead paint by the United States Environmental Protection Agency or the United States Department of Housing and Urban Development, or the American Society for Testing and Materials or the Commissioner after repair of water leaks caused by structured or plumbing deficiencies or after the removal of any chipping, peeling or flaking paint. (US)

Done by:

Guo Bei er 

(v) Give your personal opinion by reflecting on the importance of the metal and/or its compounds, and its toxicity based on your finding.

  In conclusion, our group feels that despite lead being a highly toxic element, it still holds great importance and significance in our lives. A commonly used element, lead can be found in automobile industries as well as radiation shields, and its compounds are also widely used in the production of appliances such as infrared transmitting glass, ceramics and others.

  However, consumption and exposure to lead and its compounds are detrimental to us and we can get lead poisoning from it, leading to fatalities.  Hence, we feel that it would be good if a non-poisonous alternative can be found to substitute lead without taking away the benefits of lead.

  In the mean time, we feel that we should take precautions when handling lead so that we can minimize the damage exposure to lead can cause. For example, adults should be careful with lead around children as children are more vulnerable to lead poisoning as compared to adults. Industries should also be stricter about handling of lead as incorrect methods of handling lead could lead to lead pollution and cause great harm to the environment and indirectly, to ourselves as well.  After all, prevention is better than cure. 

Done by: 
Emily Chua

Biblography

http://wanttoknowit.com/uses-of-lead/
http://kidshealth.org/parent/medical/brain/lead_poisoning.html
http://chemistry.about.com/od/howthingsworkfaqs/f/leadpoisoning.htm
http://www.epa.gov/iaq/homes/hip-lead.html