Toxic Metal Theory - Compiled Notes  
   
     
 

This section documents key quotes which relate to heavy metal contamination and the use of bone to prevent it.

 

1.0  Heavy Metals

Heavy metals are high density elements, some of which are toxic.  Electronic products often contain heavy metals like lead, mercury and cadmium and therefore need to be disposed of correctly.  Heavy metal release will contaminate soil and pollute groundwater. 

Quotes:

“Electronic waste represents 2 percent of Americas trash in landfills, but equals 70 percent of overall toxic waste.” (Slade, 2007)

“Some states in recent years in the US developed policies banning CRTs (cathode ray tubes) from landfills due to the fear that the heavy metals contained in the glass would eventually leach into groundwater.” (wikipedia, n.d.)

 

 
   
     
 

2.0  Health Risks

Heavy metal exposure can have an adverse effect on human health.  Lead exposure can lead to brain damage. Cadmium exposure can cause kidney damage and weaken bone. Mercury exposure typically occurs through eating fish from contaminated waters, and is particularly dangerous during pregnancy.  Arsenic if present within drinking water is carcinogenic and can cause skin abnormalities.  (Jarup, 2003)

 

3.0  Batteries

The public has shown increased concern over ground and surface water contamination from landfill waste disposal.  (Greghian et. al, 1981) This has resulted in tighter regulations of household hazardous materials (including used dry cell batteries) in landfills. (Asante-Duah, 1993) 

Although the public supports recycling, the collection and recycling of dry cell batteries is not commercially viable. This is due to cost, and the poor quality of recovered materials.  (IRR, 1992 cited in Asante-Duah, 1993)  Recycling of batteries may also generate further pollution streams and hazards.  (Asante-Duah, 1993) 

“The specific metals of concern from dry cell (batteries)…include cadmium (Cd), manganese (Mn), mercury (Hg), nickel (Ni) and zinc (Zn)... Cadmium  and Mercury are of greatest concern… Mercury in particular has become widely recognised as one of the most hazardous elements to human health.”  (Asante-Duah, 1993, p.219)

“In 1989 dry cell batteries contributed about 88 percent of the total mercury and 50 percent of the cadmium in the municipal solid waste stream.” (ADEG, n.d.)

“Metals in batteries will generally not be released rapidly from landfills, but the overall load of metals into the soil and the specific soils ability to adsorb metals should be viewed as critical factors to consider in deciding whether or not to landfill household batteries.”  (Asante-Duah, 1993, P.224)

“If a battery is cracked or corroded, the liquids in the landfill will pick up the metals contained in it.” (Asante-Duah, 1993, P.224)

For Example: “Cd, Ni, and Zn are believed to have low mobility in most clay soils, but mercury may have moderate ability in the same group of soils.” (Asante-Duah, 1993, P.224)

 

4.0 Bone

Bonemeal (powder) has been proven to remediate contaminated brownfield sites.

The phosphates within bone react with heavy metals, particularly Lead, Zinc and Cadmium, to form low solubility metal phosphates, which “fix” the metal in situ, and reduce the contamination of groundwater.  The heavy metals, essentially ‘merge’ with the bone.

An experiment by Mark Hodson and Eva Valsami-Jones et al. (1999) tested bonemeal on a soil sample from an industrial site and found it to be effective in remediating zinc, copper, nickel and lead. 

A separate experiment conducted by James L. Conca and Judith Wright (2006) used a processed mineral apatite II*, which is similar to the hydroxyl-apatite found in bone, to create a large permeable barrier to filter water.  They concluded that this substance was able to reduce concentrations of lead, cadmium and zinc, in ground water, by two orders of magnitude.

*apatite is a compound made up of crystallised mineral salts and calcium which is rich in phosphate

 

5.0 References

ADEQ, (n.d.) Universal Waste – Used Batteries,  Environmental Factsheet, State of Arkansas Department of Environmental Quality.  [online] Available: http://www.adeq.state.ar.us Accessed: 17/02/2008

Asante-Duah, D. K. (1993) Hazardous Waste Risk Assessment. CRC-Press.

Conca, J. & Wright, J. (2006) An Apatite II permeable reactive barrier to remediate groundwater containing Zn, Pb and Cd. Applied Geochemistry, Vol 21, Issue 8. pg.1288-1300

Greghian, A.B., Ward, D.S, and Cleary, R.W. (1981) A Finite Model for the Migration of Leachate from a Sanitary Landfill in Long Island, New York. Part 1.  Water Resour. Bull. Vol. 1, Issue 17.

Hodson, M.E., Valsami-Jones, E., Cotter-Howells J.D., Dubbin W.E.,  Kemp A.J.,  Thornton, I., Warren, A. (1999) Effect of bone meal (calcium phosphate) amendments on metal release from contaminated soils, a leaching column study. Environmental Pollution. Issue 112. pg. 233-243

IRR (1992) Institute for Risk Research

Slade, G. (2007) iWaste.  Mother Jones Journal. March/ April Issue.

Wikipedia. (n.d.) Electronic Waste.  [online] Available: http://en.wikipedia.org/wiki/Electronic_waste. Accessed 17/02/2008

 
     
 
Copyright Andrew Ross 2008