What are the main chemical and biochemical process involved in tanning
of animal hides to produce leather?

What are the health and environmental hazards of the above processes
of tanning of animal hides ?

Hi! Thanks again for the question.

In regards to tanning of animal hides to make leather, our first three
links describe the process.

"The Making of Leather"
http://www.leatherexporters.com/makingleather.htm

"Leather tanning information"
http://oror.essortment.com/leathertanning_rdcu.htm

"How is leather made?"
http://www.1stbavarianonlineshop.com/englisch/faq/leder_herstellung.htm

Our last link meanwhile explains the environmental and health concerns
for this activity. It is in PDF format and would require a reader like
the Adobe Acrobat Reader to access the file. If you haven't installed
it in your computer you can download it here
(http://www.adobe.com/products/acrobat/readstep2.html)

"Tanning * — Environmentally Relevant Activity (ERA) 54"
http://www.env.qld.gov.au/environment/business/licensing/era54tanning.pdf

Search terms used:  
tanning animal hides health problems
      
I hope these links would help you in your research once more. Before
rating this answer, please ask for a clarification if you have a
question or if you would need further information.
      
Thanks for visiting us again.       
      
Regards,       
Easterangel-ga       
Google Answers Researcher

Wonderful.Got all the information I wanted and all in just 10 pages  9
When I printed the matter ).Great going.