Clearance samples

Clearance samples Samples taken following a lead, asbestos, or other removal action, which must indicate the contaminant concentration to be at or below a specific level before the area can be cleared for normal occupation and work activities. 

A certified renovator must visually verify the cleanup in any external areas, including the ground and any exterior windowsills. Alternatively, if the owner or any law requires dust clearance sampling, that can substitute for the visual inspection. The renovator must re-clean if any dust or debris remains. ... 

In contrast to the 2006 Proposal, this final rule does not allow dust clearance sampling in lieu of post-renovation cleaning verification, except in cases where the contract between the renovation firm and the property owner or another federal, state, territorial, tribal, or local regulation requires dust clearance sampling by a certified sampling professional and requires the renovation firm to clean the work area until it passes clearance. 

Except as provided in 40 CER 745.85(c), this final rule does not allow dust clearance sampling to be performed in lieu of post-renovation cleaning verification. However, some property owners may still choose to have dust clearance sampling performed after the renovation. Dust sampling technicians certified in accordance with this final rule will be available to perform dust clearance sampling after renovations and for the purposes of HUD s Lead-Safe Housing Rule. 

Some commenters questioned the need for dust sampling technicians. One stated that there is no benefit to creating a third inspection-type discipline that has such limited training requirements. Two commenters thought that only EPA- or state-certified risk assessors should be allowed to collect dust wipe clearance samples and two commenters thought that dust... 

Therefore, the final rule does not require dust clearance sampling after any renovations, nor does it allow the signs... 

Thus, EPA believes that dust clearance sampling is a poor fit for renovation work for a variety of reasons, including the greater expense associated with clearance testing, the time necessary to obtain the results of the testing and the consequent delay in the completion of the job, and the potential to expand the scope of the renovation. 

EPA proposed to allow optional dust clearance sampling at the completion of renovation activities instead of the postrenovation cleaning verification described in 745.85(b). Some commenters agreed that the decision whether to perform clearance at the conclusion of the job should be left to the home-owner. One commenter asked EPA to require that, if a resident arranged for clearance testing and found lead hazards, the contractor would have to reclean to the resident s satisfaction. 

As discussed, dust clearance sampling and cleaning verification are not surrogates and EPA is not requiring renovation... 

In response to these comments, EPA has further considered the issue and decided to allow dust clearance sampling instead of cleaning verification only in certain limited situations. EPA agrees with the commenters that, if the rule were to allow clearance sampling instead of verification, EPA would have to require the renovator to achieve clearance, otherwise there would be no check on whether the renovation had been safely performed. HUD s Lead-Safe Housing Rule requires clearance to be achieved in many situations, as do several states. For example, the State of New Jersey requires dust clearance sampling and clearance in certain situations in multi-unit rental housing. 

For tanks having a side outlet, a tap for obtaining a clearance sample may be located 2 cm (4 in.) below the bottom of the outlet connection. Other requirements for sample taps are outlined in Table 6. 

Capillary Electrophoresis. Capillaries were first appHed as a support medium for electrophoresis in the early 1980s (44,45). The glass capillaries used are typically 20 to 200 p.m in diameter (46), may be filled with buffer or gel, and are frequendy coated on the inside. Capillaries are used because of the high surface-to-volume ratio which allows high voltages without heating effects. The only limitations associated with capillaries are limits of detection and clearance of sample components. 

FIGURE 2.7 SEC elution profiles of dextran in clinical samples, serum ( ) and urine ( ). The first peak represent dextran and the second peak inulin (used as a reference for clearance). The content of carbohydrates was determined in collected fractions with the anthrone method. [Reproduced from Hagel ef of. (1993), with permission.]... 

To further investigate the role of the liver in brevetoxin metabolism, PbTx-3 was studied in the isolated perfused rat liver model (27, 28). Radiolabeled PbTx-3 was added to the reservoir of a recirculating system and allowed to mix thoroughly with the perfusate. Steady-state conditions were reached within 20 min. At steady-state, 55-65% of the delivered PbTx-3 was metabolized and/or extracted by the liver 26% remained in the effluent perfusate. Under a constant liver perfusion rate of 4 ml/min, the measured clearance rate was 0.11 ml/min/g liver. The calculated extraction ratio of 0.55 was in excellent agreement with the in vivo data. Radioactivity in the bile accounted for 7% of the total radiolabel perfused through the liver. PbTx-3 was metabolized and eliminated into bile as parent toxin plus four more-polar metabolites (Figure 3). Preliminary results of samples stained with 4-(p-nitrobenzyl)-pyridine (29) indicated the most polar metabolite was an epoxide. 

In vitro analyses of americium are routinely performed in situations where in vivo analyses cannot be obtained or in support of an in vivo monitoring program. Urine is the preferred sample for in vitro analyses of americium, although other sample types, such as feces, tissue, bone, or blood, can also be used on a more limited basis. Urine provides for an analysis of soluble or transportable americium, fecal analysis can be used to measure ingestion or clearance of americium, and tissue is used to assess whole or regional body burdens of americium (Guilmette and Bay 1981 Ide 1986 Ide et al. 1985 Mclnroy et al. 1985). 

In situ perfusion studies assess absorption as lumenal clearance or membrane permeability and provide for isolation of solute transport at the level of the intestinal tissue. Controlled input of drug concentration, perfusion pH, osmolality, composition, and flow rate combined with intestinal region selection allow for separation of aqueous resistance and water transport effects on solute tissue permeation. This system provides for solute sampling from GI lumenal and plasma (mesenteric and systemic) compartments. A sensitive assay can separate metabolic from transport contributions. 

Although the measurement of GFR with inulin is quite accurate, it is inconvenient because it requires the continuous infusion of this exogenous substance for several hours. More often, in clinical situations, the plasma clearance of creatinine is used to estimate GFR. Creatinine, an end-product of muscle metabolism, is released into the blood at a fairly constant rate. Consequently, only a single blood sample and a 24-h urine collection are needed. Measurement of the plasma clearance of creatinine provides only an estimate of GFR in fact, this measurement slightly overestimates it. A small amount of creatinine is secreted into the urine (about 10% on average). In other words, the concentration of creatinine in the urine is the result of the amount filtered (as determined by GFR) plus the amount secreted. 

Summary of Consequences for Intestinal Microflora Failure of intestinal clearance caused by impaired motor activity or local stagnation for anatomical reasons results in Gram-negative colonization of the small bowel. Small bowel aspirate, mucosal brush, or biopsies are optional samples for culture, which is still the gold standard for detecting this type of overgrowth. 

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