Documenting and Quantifying Exposure

In case there is a possibility of exposure, it is generally necessary to ascertain exposure levels so as to identify the overall quantum of risk and/or relationship to any of the symptoms. The process of documenting and quantifying exposures usually requires practitioners to perform biological monitoring tests on the affected individuals, as well as making an assessment of the work or environmental site. It would be better if the practitioner seeks help from specialists, for instance, toxicologists, occupational/environmental medicine specialists, industrial hygienists and governmental agencies.

Based on the description of the office environment provided by the patient, specific tests can be conducted to find evidence of exposure in bodily fluids (biological monitoring) or to identify adverse health effects on target organs. It is necessary for the practitioner to know the exact agent to look out for, the appropriate test medium (blood, urine, tissue, hair), the right timing and potential influences upon test results.

• A blood test, Carboxyhemoglobin indicates carbon monoxide exposure. Carboxyhemoglobin measurement should be taken as soon as possible after the exposure because inside the body, the half-life of carbon monoxide is around 4 hours when breathing normal air in a room.
• Arsenic gets rapidly removed via the urine in a few days. It is considered a good marker to identify recent exposures, but has limited use for identifying past exposures. Seafood consumed recently can show elevated levels of arsenic in urine due to presence of nontoxic varieties of organified arsenic, which could result in mistaken interpretations of increased arsenic levels. In case increased arsenic levels are identified, practitioners need to speciate arsenic found in the urine into organic and inorganic types.
• Specific chemicals can be detected by measuring the metabolites. For instance, a number of biological monitoring tests have been suggested in order to detect exposure to the solvent toluene. This includes the measurement of metabolites in urine such as benzoic acid, hippuric acid, and o-cresol.
• An analysis of hair samples, usually performed by commercial laboratories to check for multiple elements and toxins, have not been found to be reliable and accurate, and are of little significance in the primary care setting.

Laboratory tests can also be done to check for end-organ damage and toxic effects. For instance, a blood lead concentration can be performed to detect exposure, and BUN and creatinine to check for potential effects on the kidneys. A chest radiograph and pulmonary function tests can be performed to check for effects of any past exposure to asbestos on the lungs.

An evaluation of occupational or environmental site can be done by governmental agencies, for instance, the Occupational Safety and Health Administration (OSHA) or the Environmental Protection Agency (EPA). The evaluation can also be done by private consultants, for example, certified industrial hygienists. Using personal or area sampling devices, air sampling can be performed in order to get results which can allow practitioners to make estimates based on an average eight-hour exposure period. A number of regulatory standards, for instance OSHA permissible exposure limits (PELs), make use of an eight-hour, time-weighted averages. It is possible to measure toxins present in air, soil, water and on many surfaces.

In certain cases, the correlation between levels of exposure (in the body or the environment) and health effects is good, whereas in other cases, it is poor. For instance, it is possible to measure lead present in air (micrograms/cubic meter) with a realistic correlation between air levels and blood leads found in exposed individuals. While significant individual variations exist, there is a broad correlation between recent exposure to lead and acute responses seen in adults. Usually, very little or no significant clinical effects from recent exposures are noticed, leading to blood leads less than 20 micrograms/dL. Specific symptoms such as gastrointestinal symptoms can occur at 50 micrograms/dL levels or more; and anemia presents itself with levels in excess of 80 micrograms/dL. In comparison, manganese levels (are of potential significance because methylcyclopentadienyl manganese tricarbonyl (MMT), an organic form of manganese has been utilized as a gasoline additive) detected in the air show a poor correlation with measurements recorded in the blood. Usually, levels of manganese in blood show poor correlation with the occurrence of adverse side-effects of parkinsonism and manic-depressive symptoms.

Evaluation of musculoskeletal stresses can be done qualitatively by observing job tasks being performed by workers, and more quantitatively via biomechanical analysis done by an ergonomics expert.