Human Exposure

EnviroLogix management has long believed that detecting and measuring human exposure to potentially toxic materials is a significant and largely unmet need. Current methods generally rely on broad spectrum analysis through gas chromatography or high performance liquid chromatography analysis. These techniques are certainly well documented, but they are also time consuming and expensive, and usually require rather large samples for cleanup, concentration and extraction.

To meet this need, EnviroLogix has developed several low-cost, rapid and sensitive immunoassays for routine use with urine samples. The initial suite of human exposure assays monitors the urinary metabolites of three of the most widely used herbicides in the United States, as well as DEET, the very popular insecticide which, among other applications, was widely used for troop protection during the Gulf War.

Human exposure to pesticides and industrial chemicals can arise in a number of ways, either through direct exposure in the workplace or through unaware downwind or downstream intake. Chemicals may be internalized in the body by ingestion, inhalation, absorption through the skin or by introduction through cuts and abrasions in the skin.

Click here for detailed information on our Human Exposure Monitoring Test Kits




Workplace Exposure
Workplace exposure may arise through applying pesticides or industrial chemicals, through merely handling them or mixing them for later application, through premature re-entry into recently sprayed areas, through contact with plants or soil, or in the process of cleaning up contaminated sites and transporting or disposing of contaminated soil and water.


Indirect Exposure
Indirect airborne exposure can arise from overspray, wind drift, and home or workplace application of control chemicals. Indirect waterborne exposure can result from overspray settling onto a stream or lake, from chemicals leeching into surface water from nearby sprayed or contaminated areas, or from leeching into underground water supplies which become part of public or private water supplies. Tertiary or more remote, but still potentially significant, exposure can arise through evaporation of moisture from sprayed fields which yields precipitation many miles downwind from the spray site in areas of human use or in otherwise protected water supplies.


Why test metabolites?
Many chemicals break down into harmless metabolites after exposure to sunlight. Many others, however, remain intact until they are processed within the human system where they form metabolites or combine with other elements to form new compounds. Frequently the original pesticide or industrial chemical is not detectable in human samples such as urine, saliva or serum, but one or more metabolites can be detected as markers of the human exposure.


How the tests are run
The EnviroLogix human exposure assays are non-invasive. That is, they do not require blood or serum. The tests rely instead on a urine sample. A small, measured amount of each sample is transferred from the collection cup or bottle into either a standard 96-well plate (supplied as part of the test kit) and mixed with reagents (also supplied). The sample and the reagents interact with antibodies coated on the inside of the tube or well, giving a color indication of the concentration of the chemical in the sample. For more, see "How Immunosassays Work." The 96-well plate format is quantitative. Results can be read in under2 hours.


Applications for assays
Human exposure test kits may be used as part of a work safety or hygiene program where employees are first tested at the beginning of work for a particular material, establishing a "baseline" exposure. Employees are then counseled on appropriate preventive measures, such as monitoring the delay prior to entry into an exposed area, wearing protective clothing (gloves, eyeglasses, lab coats, boots) or protective devices (facemasks or respirators) washing, etc. Periodic follow-up testing (daily, weekly, monthly, quarterly), depending on the rate of exposure and the risk involved with exposure, is then used to track exposure compared to the baseline and compared to other workers in similar circumstances. Managers, safety officers or industrial hygiene staff can then counsel employees on adherence to the prevention programs in order to curtail exposure before excessive risk levels are approached.

Typical situations where use is recommended include pesticide handlers (production, transport, mixers), pesticide applicators (farms, lawn and garden, household and commercial buildings), remediation site crews, transportation crews, and disposal teams.


Benefits from periodic testing programs
Prevention and testing, as described above, lead directly to decreased employee health risk and to a number of related cost benefits. These can include reduced sick time and down time, reduced worker compensation insurance and health insurance costs and ultimately reduced liability and liability insurance costs, all at low cost for establishing and maintaining the program(s). In addition to reducing current risks, a well-documented program can help avoid or minimize "ticking bomb" claims by demonstrating the level of worker exposure vis-à-vis federal standards, throughout employment and at termination.

Specific benefits from immunossay testing Until recently, regular prevention and testing programs were limited to the very highest risk exposures and bare minimum testing intervals. This was due to the high cost of tests per individual, slow turnaround of results (typically expressed in weeks) and the resulting inability to relate increased exposure to specific work conditions or practices.

With immunoassay test programs, the results can be documented and fed back to supervisors or employees on the spot or overnight, allowing corrective action immediately, and encouraging timely follow-up to reinforce the positive risk control benefits of appropriate procedures. While EnviroLogix' current human exposure tests are in plate format, they can also be adapted to the coated-tube format which provides results in semi-quantitative form in 20 - 35 minutes.

With costs for immunoassay tests ranging from $3 to $9 per test, in comparison to $75 to $200 per sample for historical analytical methods, the economic barrier to effective risk control is essentially removed.
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