Monitoring exposure

Effective monitoring can be difficult work. It is much more than pushing buttons on a high-tech gadget. As you will see, it is more like detective work. The issues fall into three major categories  

There are two types of air monitoring methods (1) direct reading and (2) laboratory sampling. Direct-reading instruments have built-in detectors to give on the spot results. However, there is a trade-off between sophistication and the weight of the unit The instruments must be truly portable to be useful. Therefore, it is important to be aware that there are limits to any given instrument. 

It is common to use both types of procedures to investigate exposures in the workplace. Direct-reading methods are ideal for quick checks especially when the contaminants are known or suspected. However, they are limited in accuracy. No instrument can read every contaminant. Two common instruments, organic vapor analyzer (OVA) and the photoionizer (HNU), can detect hundreds of compounds but cannot detect important toxic chemicals such as phosgene, cyanides, arsenic, or chlorine. 

You can begin to see that while direct-reading instruments can give you numbers on the spot, it takes longer to determine the actual amount of a substance present and determine the hazard to workers. You have to go through several steps to identify the chemical and then additional steps can be taken to determine the actual level of contaminants. 

Change in location—Contaminants are not evenly distributed utmost worksites. One area may have more solvents and fewer metals than another area. Monitoring often must be done when work is initiated due to the rapid change of conditions on a construction site. 

The HASP should be designed to speeify aetion levels that would eause the worker to upgrade or downgrade PPE. 

Only qualified individuals should be allowed to develop air monitoring strategies. In addition, only trained and qualified field personnel should operate sereening equipment and be allowed to interpret results. For many sites, the results obtained from direet reading instruments ean help determine a variety of important faetors on a hazardous waste site. These faetors inelude  

Direet reading instruments also ean provide an indieation of site emission levels. 

An exposure assessment uses air-monitoring data to determine possible worker exposures. This data is used to identify eontrols for worker proteetion and provide monitoring results to physieians for proper medieal assessment, treatment, and follow-up eare. 

Colorimetrie deteetor tubes are eommonly used when instantaneous results of individual eonstituents are needed immediately. However, you 

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HAZWOPER applies only where exposure to hazardous substanees or to health and safety hazards resulting from a hazardous waste operation is likely (see Eigure 2-1). This ean be determined by analysis of exposure monitoring data, hazard eharaeterization, hazard analysis, or exposure assessment [1]. Some of the speeifle examples of work aetivi-ties and situations will be eovered later. 

The HASP focuses on the specific tasks down to the worksite level and identifies job- and task-based hazards, exposure-monitoring requirements, hazard controls and approaches, requirements necessary to protect workers, and, sometimes, the name of the person responsible for a certain activity. 

Work zones are often temporary. Many times, onee the work has been eondueted, the zone boundaries ehange and sometimes beeome support zones. Temporary work zones ean be used to eflfeetively manage regulatory seope. Area and personnel exposure monitoring is erueial in order to verify that zoning, eontainments, work praetiees, and proeedures have been designed appropriately and maintain worker health and safety. 

Exposure monitoring had not been eondueted at Site A. The deeision not to eonduet monitoring was appropriately doeumented in the site safety plan and was based on the nature of the eontami-nated material. The sediments were always saturated, and the likelihood of airborne eoneentrations of PCBs was extremely low. Area samples had been eolleeted at the waste pad where the material was air-dried prior to shipping. Sample results were below the deteetable limits. 

Exposure monitoring programs were targeted toward eomplianee rather than toward the eharaeterization of employee exposures. 

W..A. Heitbrink,. M.G, Gressel, T.C. Cooper. Video exposure monitoring—,A mean.s oi saidying. sources of occupational air contaminant exposure. Part 2 Data interpretation. Ai>p . Occup. Environ. Hyg. 8(4), 199,). 

Fatal accident rate Lost-time injury rate Capital cost of accidents Number of plant/community evacuations Cost of business interruption Cost of workers compensation claims Number of hazardous material spills (in excess of a threshold) Tonnage of hazardous material spilled Tonnage of air, water, liquid and solid effluent Tonnage of polluting materials released into the environment Employee exposure monitoring Number of work related sickness claims Number of regulatory citations and fines Ecological impact of operations (loss or restoration of biodiversity, species, habitats)... 

US ERA, Occupational and Residential Exposure Test Guidelines, OPPTS 875.1000, Background for Application Exposure Monitoring Test Guidelines, Environmental Protection Agency, Washington, DC, p.l4 (1996). 

Pesticide Assessment Guidelines, Subdivision U, Applicator Exposure Monitoring, U.S. Environmental Protection Agency, Washington, D.C., 1986. 

The first pesticide exposure study was reported by Griffiths et al. (1951). Parathion was trapped on respirator filter discs during application to citrus trees. Batchelor and Walker (1954) expanded exposure monitoring to include the estimation of potential dermal exposure using pads attached to workers clothing. Durham and Wolfe (1962), in their classic review of worker exposure methodologies, also provided some experimental validation for the best available methods. 

Well-conducted studies in animals to evaluate these end points for mirex following acute- and intermediate-duration inhalation, oral, and dermal exposures would be helpful. As with the shorter duration exposures, monitoring humans who are chronically exposed to mirex by any route would be useful. 

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