Sources of Pollution,Non-radioactive Contaminants

Non-radioactive Contaminants

•          Types

•          Sources

•          Essential elements

•          Non-essential elements

•          Trace elements

•          Metals

•          Heavy metals

•          Physical (pH, EC, Total solids)

•          Chemical (Heavy metals e.g. Pb. Cd, etc.)

•          Microbiological (TBC, Coliforms, E. Coli)

Sources of Pollution

Increasing industrialization and motorization have greatly polluted the environment and consequently raised the native heavy metal levels in air, water, soil and food materials.

Elements

•          90 naturally occurring elements

•          70 metals and 20 non-metals

•          25 out of 90 – the elements of life

•           4 out of 25 (C, H, O, N) – 96% (Body)

•           Trace elements: in some tissues &          body fluids in concentration< ~ 10ppm

Trace Elements

–        Essential elements (e.g. Fe) play an important role in biological processes; their deficiency and excess adversely affect biochemical functions.

–        Non-essential elements (e.g. Pb) do not always occur in the body, they may have activity in nontoxic amounts, but if level increases becomes toxic.

Properties of Metals

•          Metallic shine or luster

•          Conductors of electricity and heat

•          Essential as well as toxic metals

•          Toxicological viewpoint: A metal is an element which under biologically significant conditions may react by losing one or more electrons to form a cation.

Toxicity

–        20 metals can give rise to rather well-defined toxic effects in man

–        Pb, Cd, As, Hg and Cr studied thoroughly. Others are Tl, Bi, Ga, In, As, Ni etc.

–        Essential

–        Cu, Cr, Fe, Co, Mn etc.

Heavy Metals (Density > 4 g/cm³ )

Ga	5.30	Cu	9.00
As	5.70	Bi	9.81
Zn	7.18	Pb	11.40
Cr	7.22	Th	11.85
In	7.33	Hg	13.60
Fe	7.90	Au	19.30
Cd	8.65	Ni	8.90