Class Notes (837,488)
Canada (510,274)
61-220 (18)
Ting (18)

general population

3 Pages
Unlock Document

Earth and Environmental Sciences

Chapter 10: Body Burdens of Industrial Chemicals in the General Population: • 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 chromatography/mass spectrometry. • 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 exceedingly difficulty. • 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 estimated. • 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 chlirone atoms. • 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 environment. • 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 consid
More Less

Related notes for 61-220

Log In


Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.