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Biomedical subjects

M R Farfel

Publications and source records attributed to M R Farfel.

11 recordsLinked to original sources
PubMed2001

Comparison of two floor mat lead dust collection methods and their application in pre-1950 and new urban houses.

This study investigated commercial floor mats as an alternative method to assess lead in residential dust in inner-city houses. Mats were placed for 3 weeks in interior entry-ways of 34 row houses built before 1950 and 17 new row houses in Baltimore City. A high volume sampler (an HVS3 floor model cyclone-based vacuum) and a hand-held portable cyclone sampler were used in the laboratory to collect side-by-side samples of mat dust. Both devices yielded comparable estimates of lead dust deposition, dust lead concentration, and dust deposition on field mat samples and had similar sampling efficiencies on mats spiked with various types of standard reference materials. The older houses had significantly higher daily lead dust deposition (mean = 130 micrograms/ft2/day by HVS3) than the newer houses (mean = 9 micrograms/ft2/day by HVS3), due to higher dust lead concentrations (mean = 1149 ppm vs mean = 107 ppm by HVS3) and not to differences in daily dust deposition (mean = 118 mg/ft2/day vs mean = 87 mg/ft2/day by HVS3) [corrected]. Mats were found to be a feasible method for the collection of dust that has accumulated for a known amount of time. Current wipe and vacuum methods do not allow for the estimation of dust deposition rates. Further research is needed to understand the role of floor mats as a risk assessment tool.

Air Pollution, Indoor↗
PubMed1994

Comparison of a wipe and a vacuum collection method for the determination of lead in residential dusts.

Lead-containing house dust is an important source of childhood lead exposure. Standard methods for collection of settled dust for evaluation of lead content have not been established. Little is known about the relationships between the various wipe and vacuum-based methods employed in past studies, preventing meaningful comparisons of results. This study characterized the relationship between a frequently used wipe dust collection method and a vacuum-based in-line filter method used to collect dust in a national survey of lead in paint and dust in U.S. housing. The correlation coefficient was 0.82 for estimates of lead loadings (PbD, mg/m2) from 71 pairs of side-by-side wipe and vacuum dust samples collected from uncarpeted floors, window sills, and exterior window wells in six dwellings. Geometric mean (GM) wipe PbD estimates exceeded those for vacuum samples by a factor of 3.9 and 5.7 for floors and window sills, respectively, findings consistent with the multiple sources of sample loss associated with the vacuum sampler. For window wells, the GM vacuum PbD estimate exceeded the GM wipe PbD estimate by a factor of 3.4, possibly due to the use of an alternative vacuum nozzle. The resulting increase in the estimated prevalence of U.S. homes with elevated dust lead loadings had wipe-sampling instead of vacuum-sampling methods been used in the national survey is discussed.

Child↗
PubMed1994

The longer-term effectiveness of residential lead paint abatement.

Residential lead-based paint and settled dust are important sources of lead exposure in U.S. children. Scant information exists on the long-term effectiveness of alternative lead abatement practices. In this extended (1.5-3.5 years) follow-up study of comprehensive abatement, 179 wipe dust samples were collected in 13 occupied dwellings for which pre- and immediately postabatement (clearance) dust lead data were available. Dust lead loadings (mg/m2) 1.5 to 3.5 years postabatement were 16, 10, and 4% of preabatement levels for floors, window sills, and window wells, respectively. Furthermore, 78% of readings remained within Maryland's interim clearance standards, indicating that sustained reductions of dust lead hazards were achieved in comprehensively abated dwellings located in older unabated housing areas.

Baltimore↗
PubMed1994

Graphite furnace atomic absorption spectroscopic measurement of blood lead in matrix-matched standards.

Now that the level of concern for a toxic blood lead concentration is 0.482 mumol/L (10 micrograms/dL), laboratories must meet new requirements to shorten analysis times and increase accuracy and precision of blood lead determinations. We used a matrix-matching method to estimate the lead concentration in blood by graphite furnace atomic absorption spectroscopy (GFAAS). For CDC proficiency samples and the NIST-Certified Blood Reference standard, the performance of this method compared favorably with that of previously published GFAAS methods and of the anodic stripping voltammetric method routinely used in our laboratory. At lead concentrations of 0.242 mumol/L (5.01 micrograms/dL) and 1.478 mumol/L (30.63 micrograms/dL), within-run CVs were 2.78% and 0.68%, respectively; between-run CVs were 4.9% and 1.35%. In 52 study samples with lead content ranging from 0.097 to 3.812 mumol/L (2 to 79 micrograms/dL), 87% of results by the matrix-modified method were within 0.048 mumol/L (1 microgram/dL) of consensus values.

Calibration↗
PubMed1991

An evaluation of experimental practices for abatement of residential lead-based paint: report on a pilot project.

In this pilot study, we prospectively evaluated experimental practices for abating lead-based paint in six dwellings. These experimental abatements were based upon a new approach to abatement which reflects current understanding of low-level lead toxicity in children and the role of lead-contaminated dust as an important contributor to children's total body burden. Our previous study of traditional abatement practices in Baltimore showed them to be inadequate for reducing lead in both house dust and children's blood. Our experimental abatements resulted in significant reductions in house dust-lead levels (PbD) which persisted during 6-9 months of followup. Geometric mean PbD at floors, window sills, and window wells were respectively 5.6, 49.6, and 316.7 mg/m2 at preabatement, and respectively 0.6, 4.4, and 10.8 mg/m2 at 6-9 months. Experimental abatements involved (1) treatment of lead-painted surfaces above and below 4 ft from the floor, including interior and exterior components of windows; (2) sealing or covering of wooden floors; (3) procedures for containment of dust during abatement; and (4) a final cleanup using a high-efficiency particle air (HEPA) vacuum. We recommend that more research be done to further evaluate and compare the long-term efficacy of these and other abatement methodologies.

Dust↗
PubMed1990

Health and environmental outcomes of traditional and modified practices for abatement of residential lead-based paint.

We evaluated traditional and modified practices for abating lead-based paint in homes of children with blood-lead concentrations (PbB) greater than 1.4 mumol/L (greater than 29 micrograms/dl). Traditional abatement resulted in acute increases in: 1) lead contaminated house dust (generally 3 to 6-fold over pre-abatement levels, but at abated sites typically 10 to 100-fold); and 2) the PbBs of nearly half of the occupant children. Modified practices represented modest short-term improvement compared to traditional practices but were also inadequate. By six months, it was clear that neither form of abatement resulted in long-term reductions of PbB or house dust lead levels, leaving children at continued risk of excessive exposure to lead and permanent adverse neurobehavioral effects. Windows were found to be high sources of lead contaminated house dust. Recommendations are made for improved abatement practices including more complete abatement of window units and more effective clean-up to remove lead-bearing dust. Thirteen million US children live in lead-painted dwellings. Research is needed to identify abatement strategies that will be practical and well suited to the current understanding of low-level lead toxicity.

Child↗
PubMed1985

Reducing lead exposure in children.

The near elimination of lead-related childhood fatalities and encephalopathy by the 1970s and the sharp decline in mean blood lead levels nationwide documented between 1976 and 1980 are two milestones in the fight against lead poisoning. In the case of the latter, we know the antecedents, such as controls on the sale, use, and lead content of lead paint, improved chelation therapy, and increased awareness and case finding; however, the antecedents' relative contributions are not known due to a lack of evaluation. Similarly, the effect of a variety of social-welfare programs has not been evaluated. Since the 1970s, our perception of the problem of lead toxicity and consequently its control has changed. First steps have been made toward attaining one primary preventive objective, controlling the multiple sources of new inputs of lead to the biosphere that contribute to asymptomatic lead toxicity. The lead content of widely used commodities has been reduced (canned foods and gasoline) or virtually eliminated (paint). The benefits of passive measures used to attain reductions in lead exposure have been documented to a greater extent than those of active programs. The best example of a successful primary and passive preventive measure is the availability of lead-free gasoline since 1974, which largely accounts for decreases in ambient air lead concentrations nationwide and the recent shift to lower values in the distribution curve of children's blood lead levels. The latter provides a margin of safety for children before known toxic levels are reached. The contribution of reductions in dietary lead to changes in blood lead levels has not been well documented. Studies also show the benefits of the use of lead-free paint in new housing. Compared to children living in older homes with deteriorating lead paint, those living in lead-free homes are at low risk for lead toxicity. Likewise, affected children who move to lead-free homes are at low risk for further toxicity. Despite reductions of new inputs, reservoirs of concentrated lead remain in urban areas in soil, dust, and existing housepaint that will continue to be hazardous to children for decades to come. The second National Health and Nutrition Examination Survey (1976-1980) described a population at continued risk of toxicity. Although lead poisoning is a problem in all socioeconomic and racial groups, poor black urban children remain at highest risk of chronic lead exposure. Compared to controlling new inputs, the control of existing sources of lead in and around housing is a more intractable problem.(ABSTRACT TRUNCATED AT 400 WORDS)

Body Burden↗
PubMed1984

Education, consent, and counseling in sickle cell screening programs: report of a survey.

In 1980, we surveyed screening facilities to determine the extent of sickle cell screening and to assess compliance with Maryland regulations. Approximately 52,000 persons were screened per year in Maryland by local health departments, hospitals, primary care centers, correctional facilities, and units dedicated entirely to screening. Thirteen thousand persons were screened without informed consent. Many facilities were deficient in providing education and counseling as well as in obtaining informed consent. Units dedicated entirely to screening were most compliant with the state regulations.

Anemia, Sickle Cell↗