• Petroleum and other materials are transformed by industrial processes into fuels,
plastic, pesticides, cosmetics, food additives and pharmaceuticals
• Residues of human made substance can now be found in the air, soil, water and
food web in the most remote reaches of the plant.
• Pollutants that are distributed ubiquitously result in universal human exposure
through inhalation, drinking water, and the food supply.
• Some of the substances to which the general human population is exposed resist
metabolism and excretion and therefore accumulate in body tissues.
• The quantity of an exogenous substance or its metabolites that has accumulated in
an individual or population is defined as a body burden.
• Body-burden estimation:
• Individual’s body burden of a pollutant is estimated by measuring the
concentration of that substance in one or more tissues, usually by gas
• Chemical body burdens are complex and dynamic in a number of ways, and these
characteristics make a full characterization of the general public body burden
• First the body of burden of a pollutant is not stable over time. It reflects a
dynamic balance between the amount of taken in and the amount excreted or
metabolized into another material
• Second, body burdens are not distributed homogenously within an individual: the
partitioning of a pollutant among various tissues and fluids reflects the substances
degradability and affinity for fats, minerals and other endogenous materials.
• The choice of compartment in biomonitoring for any pollutants will affect the
level of measured, the limit of detection and the recency of exposure being
• Third, the body of burden of an individual in todays environment consist of
hundred of syntehic substances.
• Biomonitoring programs in the United States:
• Public health officials and scientists use biomonitoring information for
surveillance, control and treatment
• The purpose of many biomonitoring programs has been to assess the health risks
of occupationally or environmentally exposed individuals.
• Three biomonitoring surveys have studied broad samples of the U.S population.
• The NHATS programs has been criticized for lacking a standardized methodology
and using a sample of individuals that may not accurately reflect the nation
populations, but the programs results remain one of the most comprehensive
available data sets on the general populations body burden.
• A reference range is defined as the concentration of a particular substance that is
excepted to be present in the genral population with no unusal chemical exposure.
• The reference range is the standard against which a measuring laboratory can say
that results for any group or indivudal are high in a normal range or low.
• Organochlorine substance: • Organochlorine are a class of carbon based chemicals that contain one or more
• Thousands of additional organochlorines are formed as a by-products in the
manufacture, some uses and disposal of organochrline containin product.
• Three characteristics of organochlorines make them particularly troublesome.
First chloringation changes the chemical stability of organic chemicals in largly
predictable ways, making many organcholrines highly persistent in the
• Second, many organochlirones are strongly lipophilic—that is they are highly
soluble in fats but not in water, so they accumulate in fatty tissues.
• Chlorination almost invariably increase the solulbility of organic substances in fat
and reduces their water solubility, the increase in lipophhiia become greater with
each chlorine atom added to the molecule.
• Finally organochlirines tend to be considerably more toxic and more carcinogenic
than their nonchrliroinated analogues.
• Some organchlor