Biomarker exposure

There are several interesting features of the phthalate biomarker-exposure dose analyses. First, women and children have greater exposure to several phthalates than male adults. That may be due to the use of cosmetics and personal-care products in the case of women and due to higher food intake rate per body weight and exposure to plasticizers in toys in children. Data on children younger than 6 years old are not available, and this may be an important data gap. The other feature of note is that the relatively small German study found exposures to some phthalates that were 3-20 times above those found in the United States, whereas for other phthalates the exposure differential was smaller and concentrations in the United States were greater (Koch et al. 2003). That implies a different exposure pattern in different countries. 

Chapter 5 described general limitations of extrapolating workplace biomarker indices, such as Biological Exposure Indices (BEIs) to the general public. However, biomarker-exposure dose relationships established in the workplace may have utility for developing pharmacokinetic models that could be used to interpret biomonitoring data on the general public. 

This section describes the identification and evaluation of biomarkers (Section 26.3.1) and the major types of biomarkers—exposure, effect, and susceptibility (Sections 26.3.2 to 26.3.4) the subdiscipline of genetic susceptibility is discussed in greater detail in Section 26.4. 

Domestic and natural combustion of coal, wood and other organic materials supply a steady source of PAHs. The environmental ubiquity of several aromatic representatives together with their procarcenogenic and mutagenic properties also created a great deal of interest in the formation of PAHs in fuel-rich flames as well as in the emission, occurrence and analysis of PAHs combined with aspects of metabolism, deoxyribonucleic acid (DNA)-adduct formation, biomarkers, exposure and risk assessment [23]. 

Paustenbach, D. and Galbraith D., Biomonitoring and biomarkers Exposure assessment will never be the same. Environ. Health Perspect., 114, 1143, 2006. 

Paustenbach, Deimis, and David Galbraith, Biomonitoring and Biomarkers Exposure Assessment Will Never be the Same, Environmental Health Perspectives 114, 1143-1149 (2006). 

COMPARATIVE STUDY OF SPE AND LEE FOR PRECONCENTRATION OF URINARY 1-HYDROXYPYRENE AS A BIOMARKER OF EXPOSURE TO PAHS PRIOR TO HPLC... 

Cyprid major protein is a larval storage protein necessary for successful metamorphosis. " Production of cyprid major protein was increased in the barnacle Balanus amphitrite following exposure to both nonylphenol and estradiol, suggesting that it may be a potential biomarker of estrogen exposure in invertebrates such as barnacles. " "... 

Mechanistic studies to identify how endocrine disrupting chemicals interact with hormone systems are required. Although population effects coupled with biomarkers of exposure are strongly suggestive of endocrine disruption, the effect could be secondary to metabolic toxicity. Establishing mechanisms may avoid the need to make decisions on a weight of evidence approach alone. 

Extensive research is currently underway to use biological markers (biomarkers) in exposure and risk assessment. Biomarkers include the reaction products of chemicals or their metabolic products with biological macromolecules, especially with DNA. They also involve indicators of effect, such as chromosomal damage, and indicators of individual genetic susceptibility. 

Biomarkers for internal close of the intoxicant—dose monitoring. Bioniarkers for early biological changes following exposure— effect... 

Animal-to-Human Extrapolations ENDOCRINE DISRUPTION CHILDREN S SUSCEPTIBILITY BIOMARKERS OF EXPOSURE AND EFFECT... 

Biomarkers Used to Identify or Quantify Exposure to Methyl Parathion... 

Biomarkers are broadly defined as indicators signaling events in biologic systems or samples. They have been classified as markers of exposure, markers of effect, and markers of susceptibility (NAS/NRC 1989). 

Due to a nascent understanding of the use and interpretation of biomarkers, implementation of biomarkers as tools of exposure in the general population is very limited. A biomarker of exposure is a xenobiotic substance or its metabolite(s), or the product of an interaction between a xenobiotic agent and some target molecule(s) or cell(s) that is measured within a compartment of an organism (NAS/NRC 1989). The preferred biomarkers of exposure are generally the substance itself or substance-specific metabolites in readily obtainable body fluid(s) or excreta. However, several factors can confound the use and... 

A biomarker of susceptibility is an indicator of an inherent or acquired limitation of an organism s ability to respond to the challenge of exposure to a specific xenobiotic substance. It can be an intrinsic genetic or other characteristic or a preexisting disease that results in an increase in absorbed dose, a decrease in the biologically effective dose, or a target tissue response. If biomarkers of susceptibility exist, they are discussed in Section 3.10 Populations That Are Unusually Susceptible. 

The most specific biomarker of exposure to methyl parathion is the presence of the compound in serum or tissue. This is an especially good biomarker for detection shortly after acute exposure. For example, methyl parathion levels were detected in the sera of five men who were exposed for 5 hours in a cotton field 12 hours after it was sprayed with methyl parathion. The route of exposure was dermal, through unprotected hands. Serum levels averaged 156 ppb after 3 hours of the 5-hour exposure, and averaged 101.4 and 2.4 ppb at 7 and 24 hours postexposure, respectively (Ware et al. 1975). 

Following exposure of humans to organophosphates, but not specifically methyl parathion, restoration of plasma cholinesterase occurs more rapidly than does restoration of erythrocyte cholinesterase (Grob et al. 1950 Midtling et al. 1985). These findings are supported by studies of methyl parathion in animals. Erythrocyte cholinesterase levels are representative of acetylcholinesterase levels in the nervous system, and, therefore, may be a more accurate biomarker of the neurological effects of chronic low level exposure of humans to methyl parathion (Midtling et al. 1985 NIOSH 1976). 

Methyl parathion has been detected in blood within 1 day of exposure and is a specific biomarker (Fazekas 1971). 

The purpose of this chapter is to describe the analytical methods that are available for detecting, measuring, and/or monitoring methyl parathion, its metabolites, and other biomarkers of exposure and effect to methyl parathion. The intent is not to provide an exhaustive list of analytical methods. Rather, the intention is to identify well-established methods that are used as the standard methods of analysis. Many of the analytical methods used for environmental samples are the methods approved by federal agencies and organizations such as EPA and the National Institute for Occupational Safety and Health (NIOSH). Other methods presented in this chapter are those that are approved by groups such as the Association of Official Analytical Chemists (AOAC) and the American Public Health Association (APHA). Additionally, analytical methods are included that modify previously used methods to obtain lower detection limits and/or to improve accuracy and precision. 

Anwar WA. 1997. Biomarkers of human exposure to pesticides. Environ Health Perspect Suppl 105 (Supplement 4) 801-806. 

Gupta RC, Goad JT, Kadel WL. 1996. Distribution and responses of brain biomarkers to anticholinesterase insecticides exposure. FASEB J 10 A690. 

Gupta RC, Goad JT, Milatovic D, et al. 2000. Cholinergic and noncholinergic brain biomarkers of insecticide exposure and effects. Hum Exp Toxicol 19 297-308. 

Laurent C, Jadot P, Chabut C. 1996. Unexpected decrease in cytogenetic biomarkers frequencies observed after increased exposure to organophosphorus pesticides in a production plant. Int Arch Occup Environ Health 68 399-404. 

Nigg HN, Knaak JB. 2000. Blood cholinesterases as human biomarkers of organophosphorus pesticide exposure. Rev Environ Contam Toxicol 163 29-112. 

Section 2.8 Biomarkers of Exposure and Effect Section 2.11 Methods for Reducing Toxic Effects... 

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