Shirley Robertson

Analytical Performance Criteria

The past five years have seen a move towards standardizing the documentation of measurement uncertainty through nearly worldwide adoption of the International Organization for Standardization Guide...

Evaluation of the prevalence of antiwheat-, anti-flour dust, and anti—α-amylase specific IgE antibodies in US blood donors

BACKGROUND Asthma in bakery workers is one of the most frequently occurring forms of occupational asthma in the world. Experience from other countries has shown the prevalence of sensitization (IgE) to bakery-associated allergens (BAAs) (wheat [W], flour dust [FD], alpha-amylase [AA]) in bakery workers to be 5% to 53%, whereas the prevalence in nonoccupationally exposed individuals was estimated to be 1.2% to 6.4%. OBJECTIVE To estimate the prevalence of BAA sensitization by measuring BAA specific IgE in the residual serum tubes of volunteer blood donors. METHODS Serum samples from 534 volunteer blood donors were measured for anti-W, anti-FD, and anti-AA specific IgE antibodies (in duplicate) using the AlaSTAT microplate assay. Samples with BAA IgE concentrations of 0.35 kU/L or greater were considered positive. RESULTS Nineteen of 530 serum samples (3.6%; 95% confidence interval [CI], 3.3%-3.9%) were positive for W (range, 0.38-3.61 kU/L), whereas 31 of 534 (5.8%; 95% CI, 5.3%-6.3%) were positive for FD (range, 0.35-2.34 kU/L) and 5 of 529 (1.0%; 95% CI, 0.9%-1.1%) were positive for AA (range, 0.38-1.59 kU/L). Thirteen serum samples were positive for both W and FD; 1 sample each was positive for W and AA and FD and AA. CONCLUSIONS The prevalence of IgE sensitization in serum samples from a relatively large unselected population of volunteer blood donors is 1.0% for AA, 3.6% for W, and 5.8% for FD, which agrees well with data from other countries for sensitization prevalence rates for nonoccupationally exposed individuals.

Development and validation of an ELISA for metolachlor mercapturate in urine

The National Institute for Occupational Safety and Health (NIOSH) has conducted an exposure assessment study of herbicide applicators exposed to numerous commercial acetanilide-containing products. An enzyme-linked immunosorbant assay (ELISA) was developed to measure the putative major human metabolite of one of these, metolachlor mercapturate (MM). Antibodies were obtained by immunizing rabbits with a keyhole limpet hemocyanin (KLH) MM conjugate and the sera used as a source of IgG antibodies for the ELISA development. The percent cross-reactivities for metolachlor (ME), acetochlor mercapturate (ACM), alachlor mercapturate (AM) and alachlor (AL) were 39 and 23, respectively. Cross-reactivity for alachlor mercapturate (AM) and alachlor (AL) are not given as 50% inhibition was not observed for the highest concentration tested. Percent inhibitions at 20 μg l -1 for MM, ME, ACM, AM and AL were 20, 29, 48, 72 and 90, respectively. The measured least detectable dose (LDD) of metolachlor mercapturate was 0.18 μg l - 1 . Inter-assay concordance was <15%. These data indicate that the MM ELISA developed in this study may be used to estimate body burdens of ME from urinary metabolites of herbicide applicators.

Use of immunoassays for biomonitoring of herbicide metabolites in urine

Abstract Commercially available ground-water immunoassays (RaPID Assay ® ) are being evaluated to determine their potential value for measuring herbicides or their metabolites in urine. Preliminary investigations of matrix effects and cross-reactivities indicate potential usefulness for the atrazine kit, but not the metolachlor kit, as a urinary biomonitoring tool.

Measurement of multiple drugs in urine, water, and on surfaces using fluorescence covalent microbead immunosorbent assay

There are a range of applications that require the measurement of multiple drugs such as urine analysis, drug determination in water, and screening for drug contamination on surfaces. Some of the procedures used such as enzyme-linked immunosorbent assay (ELISA) are simple but can only determine one drug at a time, and others such as GC-MS or LC-MS are complex, time-consuming, and expensive. In this study, fluorescence covalent microbead immunosorbent assay (FCMIA) was investigated as a simple method for the measurement of multiple drugs simultaneously in three matrices: diluted urine, water, and on surfaces. Five different drugs of abuse or their metabolites (methamphetamine, caffeine, benzoylecgonine (a metabolite of cocaine), tetrahydrocannabinol (THC), the active ingredient in marijuana, and oxycodone) were studied over the range 0–15 ng/ml. There was no measureable cross-reactivity among the drugs at the concentrations studied. Urine dilutions from 1/50 to 1/2.5 were studied and dilutions less than 1/20 had a significant effect on the methamphetamine assay but limited effects on the benzoylecgonine and oxycodone assays and almost no effect on the THC assay. For assays performed in 1/20 urine dilution, water, and diluted surface sampling buffer, least detectable doses (LDD) were 1 ng/ml or less for the drugs. Surfaces spiked with drugs were sampled with swabs wetted with surface sampling buffer and recoveries were linear over the range 0–100 ng/100 cm2 surface loading for all drugs. FCMIA has potential to be used for the measurement of multiple drugs in the matrices studied.

A Pilot Study of Workplace Dermal Exposures to Cypermethrin at a Chemical Manufacturing Plant

Exposure during the manufacture of pesticides is of particular concern due to their toxicity and because little is known about worker exposure, since most studies have focused on end-use application within agriculture or buildings. Even though dermal exposure can be expected to dominate for pesticides, little is known about workplace dermal exposures or even appropriate methods for their assessment. The current study begins to address this gap by evaluating alternative methods for assessing dermal exposure at a chemical manufacturing plant. For this pilot study, eight workers were recruited from a U.S. plant that produced the pesticide cypermethrin. Exposure was evaluated using three approaches: (1) survey assessment (questionnaire), (2) biological monitoring, and (3) workplace environmental sampling including ancillary measurements of glove contamination (interior and exterior). In each case, cypermethrin was quantified by enzyme-linked immunosorbent assay (ELISA). Environmental measurements identified two potential pathways of cypermethrin exposure: glove and surface contamination. Workplace exposure was also indicated by urine levels (specific gravity adjusted) of the parent compound, which ranged from 35 to 253 μg/L (median of 121 μg/L) with no clear trend in levels from pre- to post-shift. An exploratory analysis intended to guide future studies revealed a positive predictive association (Spearman correlation, p ≤ 0.10) between post-shift urine concentrations and a subset of survey questions evaluating worker knowledge, attitudes, and perceptions (KAP) of workplace dermal hazards, i.e., personal protective equipment self-efficacy, and inverse associations with behavior belief and information belief scales. These findings are valuable in demonstrating a variety of dermal exposure methods (i.e., behavioral attributes, external contamination, and biomarker) showing feasibility and providing measurement ranges and preliminary associations to support future and more complete assessments. Although these pilot data are useful for supporting design and sample size considerations for larger exposure and health studies, there is a need for validation studies of the ELISA assay for quantification of cypermethrin and its metabolites in urine.

The use of immunochemical and biosensor methods for occupational and environmental monitoring. Part I: introduction to immunoassays.

The past five years have seen a move towards standardizing the documentation of measurement uncertainty through nearly worldwide adoption of the International Organization for Standardization Guide...

Analytical Performance Criteria: The Use of Immunochemical and Biosensor Methods for Occupational and Environmental Monitoring. Part II: Immunoassay Data Analysis and Immunobiosensors

T his is the second of a two-part series on the use of immunochemical and biosensor methods for occupational and environmental monitoring. In Part I (Introduction to Immunoassays), a general overview of the immunology and types of immunoassays was discussed. The major types of enzyme-linked immunosorbent assays (ELISAs), radioimmunoassays (RIA), and lateral flow techniques were described. In the present column, how data are reduced from immunoassays is addressed and some state-ofthe-art immunobiosensors are introduced.

Field evaluation of onsite near real-time monitors for surface contamination by 5-fluorouracil

Objectives In order to produce near real-time onsite results to detect surface contamination by antineoplastic drugs, the National Institute for Occupational Safety and Health developed monitors for 5-fluorouracil, which use surface wiping and lateral flow immunoassay for measurement. The monitors were tested in the laboratory to assess the sensitivity of detection on laboratory-produced contaminated surfaces. A field evaluation to assess the capability of the monitors to make measurements in healthcare workplaces was carried out in collaboration with a medical device company and the results are presented in this report. Methods The 5-fluorouracil monitor was evaluated in areas where oncology drugs were prepared and administered to patients at five different hospitals. The levels of contamination measured with the monitors were compared to levels measured with liquid chromatography-tandem mass spectrometry. Results The 5-fluorouracil values measured with the liquid chromatography-tandem mass spectrometry ranged from 0 to over 200,000 ng/100 cm2. Measurements by the 5-fluorouracil monitors in the range 10–100 ng/100 cm2 correlated with the liquid chromatography-tandem mass spectrometry. Receiver operating characteristic curves developed for the data indicated that a positive limit of 22 ng/100 cm2 would give an acceptable level of false-positives while retaining most true-positive samples. If the liquid chromatography-tandem mass spectrometry measured greater than 100 ng/100 cm2, then the monitors also measured levels greater than 100 ng/100 cm2 for the majority of samples. Conclusion The data indicate that there are many areas in hospitals that are contaminated with 5-fluorouracil and the monitors will be useful in identifying this contamination.

Analytical Performance Criteria: The Use of Immunochemical and Biosensor Methods for Occupational and Environmental Monitoring. Part I: Introduction to Immunoassays

The past five years have seen a move towards standardizing the documentation of measurement uncertainty through nearly worldwide adoption of the International Organization for Standardization Guide...