A Snapshot of Lead in Consumer Products Across Four US Jurisdictions.

BACKGROUND: Following the removal of lead from gasoline, paint and pipes were thought to be the main sources of lead exposure in the United States. However, consumer products, such as certain spices, ceramic and metal cookware, traditional health remedies, and cultural powders, are increasingly recognized as important sources of lead exposure across the United States. OBJECTIVE: This paper reviews data from four US jurisdictions that conduct in-home investigations for children with elevated blood lead levels (BLLs) to examine the prevalence of lead exposures associated with consumer products, in comparison with housing-related sources. METHODS: Authors reviewed investigation data (2010-2021) provided by California, Oregon, New York City, and King County, Washington, and compared the extent of lead exposures associated with housing-related vs. consumer products-related sources. DISCUSSION: The proportion of investigations identifying consumer products-related sources of lead exposure varied by jurisdiction (range: 15%-38%). A review of US CDC and US FDA alerts and New York City data indicates that these types of lead-containing products are often sourced internationally, with many hand carried into the United States during travel. Based on surveillance data, we believe that US immigrant and refugee communities are at an increased risk for lead exposures associated with these products. To engage health authorities, there is a need for evidentiary data. We recommend implementing a national product surveillance database systematically tracking data on consumer products tested by childhood lead poisoning prevention programs. The data repository should be centralized and accessible to all global stakeholders, including researchers and governmental and nongovernmental agencies, who can use these data to inform investigations. Effectively identifying and addressing the availability of lead-containing consumer products at their source can focus resources on primary prevention, reducing lead exposures for users abroad and in the United States. https://doi.org/10.1289/EHP14336.

Evaluating metal cookware as a source of lead exposure.

BACKGROUND: We previously demonstrated that aluminum cookware brought from Afghanistan by resettled families as well as some aluminum cookware available for purchase in the United States represent a previously unrecognized source of lead exposure. However, the extent to which this cookware represents a source of lead exposure to other United States residents is unclear. OBJECTIVES: To test additional cookware for lead content and its propensity to leach lead and other toxic metals. This will further our understanding of the extent to which this cookware represents a lead poisoning risk in the United States and elsewhere. METHODS: We screened an additional 28 pieces of aluminum cookware and 5 brass items for lead content using an X-ray fluorescence (XRF) analyzer and used our leachate method to estimate the amount of lead that migrates into food. We also tested 17 additional stainless steel items to determine whether they would be safer alternatives. RESULTS: Many aluminum cookware products contained in excess of 100 parts per million (ppm) of lead. Many also leached enough lead under simulated cooking and storage conditions to exceed recommended dietary limits. One hindalium appam pan (an Indian frying pan/wok) leached sufficient lead to exceed the childhood limit by 1400-fold. Brass cookpots from India also yielded high lead levels, with one exceeding the childhood limit by over 1200-fold. In contrast, stainless steel cookware leached much lower levels of lead. IMPACT: Aluminum and brass cookware available for purchase in the United States represents a previously unrecognized source of lead exposure.

Investigating aluminum cookpots as a source of lead exposure in Afghan refugee children resettled in the United States.

BACKGROUND: Afghan refugee children resettled in Washington State have the highest prevalence of elevated blood lead levels (BLLs) of any other refugee or immigrant population. Resettled families brought several lead-containing items with them from Afghanistan, including aluminum cookpots. OBJECTIVES: To evaluate the potential contribution of lead-containing cookpots to elevated BLLs in Afghan children and determine whether safer alternative cookware is available. METHODS: We screened 40 aluminum cookpots for lead content using an X-ray fluorescence (XRF) analyzer and used a leachate method to estimate the amount of lead that migrates into food. We also tested five stainless steel cookpots to determine whether they would be safer alternatives. RESULTS: Many aluminum cookpots contained lead in excess of 100 parts per million (ppm), with a highest detected concentration of 66,374 ppm. Many also leached sufficient lead under simulated cooking and storage conditions to exceed recommended dietary limits. One pressure cooker leached sufficient lead to exceed the childhood limit by 650-fold. In contrast, stainless steel cookpots leached much lower levels of lead. SIGNIFICANCE: Aluminum cookpots used by refugee families are likely associated with elevated BLLs in local Afghan children. However, this investigation revealed that other U.S. residents, including adults and children, are also at risk of poisoning by lead and other toxic metals from some imported aluminum cookpots. IMPACT STATEMENT: Some aluminum cookware brought from Afghanistan by resettled families as well as cookpots available for purchase in the United States represent a previously unrecognized source of lead exposure.

Using an alternatives assessment framework to evaluate waterborne versus solventborne basecoats used in automotive refinishing.

We evaluated two types of automotive basecoats used in automotive refinishing (i.e., in auto body shops): waterborne and solventborne. The primary tool we used for this evaluation was the Alternatives Assessment Guide (version 1.0) developed by the Interstate Chemicals Clearinghouse (IC2). The term "solventborne," as used in this article, refers to products that contain relatively high concentrations of volatile organic compounds (referred to as "high-volatile organic compound [VOC] basecoats" in the industry). These products are distinct from the "low-VOC" solventborne products used widely in California and elsewhere. From a health and environmental hazard perspective, our evaluation found that waterborne basecoats contained fewer hazardous ingredients and at lower concentrations than their solventborne counterparts. Automotive painters who spray-painted vehicles with waterborne products experienced significantly lower exposures to several harmful solvents. Waterborne products are readily available and offer advantages with regard to social impacts. Some of these advantages include lower worker and community exposure to VOCs, reduced VOC release and smog formation, and reduced potential for generation of and exposure to hazardous waste. Based on our assessment in auto body shops, we consider waterborne basecoats to be safer alternatives from both a human health and environmental perspective. Integr Environ Assess Manag 2022;18:1101-1113. Published 2021. This article is a U.S. Government work and is in the public domain in the USA.

Perchloroethylene and Dry Cleaning: It's Time to Move the Industry to Safer Alternatives.

Perchloroethylene (PERC) is the most common solvent used for dry cleaning in the United States. PERC is a reproductive toxicant, neurotoxicant, potential human carcinogen, and a persistent environmental pollutant. The Environmental Protection Agency is evaluating PERC under the Frank R. Lautenberg Chemical Safety for the 21st Century Act, which amended the Toxic Substances Control Act (amended TSCA), and has mandated that PERC dry cleaning machines be removed from residential buildings. Some local and state programs are also requiring or facilitating transitions to alternative cleaning technologies. However, the potential for these alternatives to harm human health and the environment is not well-understood. This review describes the issues surrounding the use of PERC and alternative solvents for dry cleaning while highlighting the lessons learned from a local government program that transitioned PERC dry cleaners to the safest current alternative: professional wet cleaning. Implications for future public health research and policy are discussed: (1) we must move away from PERC, (2) any transition must account for the economic instability and cultural aspects of the people who work in the industry, (3) legacy contamination must be addressed even after safer alternatives are adopted, and (4) evaluations of PERC alternatives are needed to determine their implications for the long-term health and sustainability of the people who work in the industry.

Occupational exposures to new dry cleaning solvents: High-flashpoint hydrocarbons and butylal.

The dry cleaning industry is moving away from using perchloroethylene. Occupational exposures to two alternative dry cleaning solvents, butylal and high-flashpoint hydrocarbons, have not been well characterized. We evaluated four dry cleaning shops that used these alternative solvents. The shops were staffed by Korean- and Cantonese-speaking owners, and Korean-, Cantonese-, and Spanish-speaking employees. Because most workers had limited English proficiency we used language services in our evaluations. In two shops we collected personal and area air samples for butylal. We also collected air samples for formaldehyde and butanol, potential hydrolysis products of butylal. Because there are no occupational exposure limits for butylal, we assessed employee health risks using control banding tools. In the remaining two shops we collected personal and area air samples for high-flashpoint hydrocarbon solvents. In all shops the highest personal airborne exposures occurred when workers loaded and unloaded the dry cleaning machines and pressed dry cleaned fabrics. The air concentrations of formaldehyde and butanol in the butylal shops were well below occupational exposure limits. Likewise, the air concentrations of high-flashpoint hydrocarbons were also well below occupational exposure limits. However, we saw potential skin exposures to these chemicals. We provided recommendations on appropriate work practices and the selection and use of personal protective equipment. These recommendations were consistent with those derived using control banding tools for butylal. However, there is insufficient toxicological and health information to determine the safety of butylal in occupational settings. Independent evaluation of the toxicological properties of these alternative dry cleaning solvents, especially butylal, is urgently needed.

Characterization of "Hydrocarbon" Dry Cleaning in King County, Washington.

In King County, Washington, the most frequently used alternative solvent to perchloroethylene is a hydrotreated petroleum hydrocarbon. The objectives of the authors' study were to 1) determine the frequency of use of process chemicals used in "hydrocarbon" dry cleaning and gather other operational information; 2) chemically characterize the process chemicals; 3) characterize the still bottoms and separator water wastes according to dangerous waste and wastewater discharge regulations; 4) identify linkages between work practices, process chemicals, and the chemical composition of the waste streams; and 5) evaluate the aquatic toxicity of the hydrocarbon solvent and detergent. Many hydrocarbon dry cleaners are using process chemicals that contain hazardous substances, including trichloroethylene. One sample of separator water contained 13,000 µg/L trichloroethylene. This sample was determined to be federal hazardous waste, state-only dangerous waste (i.e., according to Washington state-specific regulations), and failed wastewater discharge thresholds. All still bottoms were determined to be state-only dangerous wastes. Efforts should be directed towards replacing hazardous spot cleaning chemicals with safer alternatives and ensuring that wastes are disposed of appropriately.

A health and environmental profile of the dry cleaning industry in King County, Washington.

Workers in the dry cleaning industry are exposed to a variety of harmful solvents, and poor work practices can result in extensive environmental contamination. Of particular concern is perchloroethylene (PERC), which is the most commonly used cleaning solvent. This chlorinated hydrocarbon is a pervasive environmental contaminant and a probable human carcinogen. PERC is also a neurotoxin and is toxic to the liver and kidneys. The study described here was comprised of key informant interviews, site visits, and a countywide business survey. The 64% response rate to the survey suggests that the results are likely representative of King County's dry cleaning industry. Dry cleaning was determined to be dominated by small, Korean-owned, family-run businesses. Although the use of PERC as the primary dry cleaning agent has decreased in recent years, this solvent is still used by the majority of businesses. This industry would benefit from regulatory intervention in concert with an educational campaign and enhanced technical and financial assistance. For any intervention to be effective, however, it must account for the unique financial and demographic characteristics of this industry.

Airborne isocyanate exposures in the collision repair industry and a comparison to occupational exposure limits.

Isocyanate exposure was evaluated in 33 spray painters from 25 Washington State autobody shops. Personal breathing zone samples (n = 228) were analyzed for isophorone diisocyanate (IPDI) monomer, 1,6-hexamethylene diisocyanate (HDI) monomer, IPDI polyisocyanate, and three polyisocyanate forms of HDI. The objective was to describe exposures to isocyanates while spray painting, compare them with short-term exposure limits (STELs), and describe the isocyanate composition in the samples. The composition of polyisocyanates (IPDI and HDI) in the samples varied greatly, with maximum amounts ranging from up to 58% for HDI biuret to 96% for HDI isocyanurate. There was a significant inverse relationship between the percentage composition of HDI isocyanurate to IPDI and to HDI uretdione. Two 15-min STELs were compared: (1) Oregon's Occupational Safety and Health Administration (OR-OSHA) STEL of 1000 µg/m(3) for HDI polyisocyanate, and (2) the United Kingdom's Health and Safety Executive (UK-HSE) STEL of 70 µg NCO/m(3) for all isocyanates. Eighty percent of samples containing HDI polyisocyanate exceeded the OR-OSHA STEL while 98% of samples exceeded the UK-HSE STEL. The majority of painters (67%) wore half-face air-purifying respirators while spray painting. Using the OR-OSHA and the UK-HSE STELs as benchmarks, 21% and 67% of painters, respectively, had at least one exposure that exceeded the respirator's OSHA-assigned protection factor. A critical review of the STELs revealed the following limitations: (1) the OR-OSHA STEL does not include all polyisocyanates, and (2) the UK-HSE STEL is derived from monomeric isocyanates, whereas the species present in typical spray coatings are polyisocyanates. In conclusion, the variable mixtures of isocyanates used by autobody painters suggest that an occupational exposure limit is required that includes all polyisocyanates. Despite the limitations of the STELs, we determined that a respirator with an assigned protection factor of 25 or greater is required to protect against isocyanate exposures during spray painting. Consequently, half-face air-purifying respirators, which are most commonly used and have an assigned protection factor of 10, do not afford adequate respiratory protection.

Survey of dermal protection in Washington State collision repair industry.

Substantial exposure to isocyanates may occur during spray painting in autobody shops, yet information is lacking on the efficacy of the protective clothing used during spray painting. We investigated the personal and workplace factors associated with painters' dermal protection use during a large-scale exposure assessment study. Survey data indicated that 69% of painters always used gloves, with latex gloves (47%) and nitrile gloves (34%) used most frequently. Among latex glove users, 53% used thin latex (0.05-0.13 mm), 6% used medium latex (0.15-0.20 mm), and 12% used thick latex (> 0.20 mm). Among nitrile glove users, 27% used thin nitrile and 45% used medium nitrile. Sixty-three percent of painters always used coveralls, 44% preferring one particular brand. Although overspray presents an opportunity for dermal exposure to the neck and face, only 19% of painters protected these areas with personal protective equipment. Painters who always used coveralls were more likely to use gloves (odds ratio = 7.9, p = 0.061). Painters who reported ever having smoked cigarettes used gloves (p = 0.05) and coveralls (p = 0.04) more frequently. Painters who sprayed more than 34 clear coat jobs per month used coveralls most frequently (p = 0.038). Exact logistic regressions along with random sample calculations indicated that the survey results were independent of the shops. Because of the small sample size in this study, future research is warranted to corroborate these results. Studying the effectiveness of gloves and coveralls against polyurethane paints and understanding the underlying motivators and preferences for painters and business owners is needed for the development of best practices for the selection and use of dermal protection.

Hemoglobin adducts in workers exposed to 1,6-hexamethylene diisocyanate.

We investigated the utility of 1,6-hexamethylene diamine (HDA) hemoglobin adducts as biomarkers of exposure to 1,6-hexamethylene diisocyanate (HDI) monomer. Blood samples from 15 spray painters applying HDI-containing paint were analyzed for hemoglobin HDA (HDA-Hb) and N-acetyl-1,6-hexamethylene diamine (monoacetyl-HDA-Hb) by GC-MS. HDA-Hb was detected in the majority of workers (≤1.2-37 ng/g Hb), whereas monoacetyl-HDA-Hb was detected in one worker (0.06 ng/g Hb). The stronger, positive association between HDA-Hb and cumulative HDI exposure (r(2) = 0.3, p < 0.06) than same day exposure (p ≥ 0.13) indicates long-term elimination kinetics for HDA-Hb adducts. This association demonstrates the suitability of HDA-Hb adducts for further validation as a biomarker of HDI exposure.

Field comparison of air sampling methods for monomeric and polymeric 1,6-hexamethylene diisocyanate.

This study was to critically compared 13 different air samplers for their ability to monitor air exposures to monomeric and polymeric 1,6-hexamethylene diisocyanate (HDI) in the automotive refinishing industry. Using both fast- and slow-drying clearcoat, we tested the following types of samplers: single- and dual-stage 37-mm polypropylene (PP) and polystyrene (PS) samplers (open- and closed-face), IOM (with plastic and stainless steel inserts), OSHA42, IsoChek, and WA-DOSH samplers. Midget impingers with frit were used as reference samplers. We observed the PP, PS, and IOM samplers to measure greater levels of HDI monomer and biuret when a fast-drying clearcoat was applied compared with a slow-drying clearcoat. When a slow-drying clearcoat was applied, the open-face PP and PS samplers measured significantly more monomeric and polymeric HDI (2-fold; p < 0.003) than the closed-face PP and PS samplers. We determined that significantly more monomeric and polymeric HDI were measured by impingers (1.3-1.9-fold) compared with single-stage PP/PS (N = 59), dual-stage PP/PS (N = 59), or IOM (N = 24) samplers. However, when stratified by cassette characteristics, the open-face single-stage PP and PS samplers performed equally to the impingers for HDI monomer when a fast-drying clearcoat was applied, and for all analytes when a slow-drying clearcoat was applied. Significantly higher HDI monomer concentrations (1.2-3.1-fold; p = 0.001) were measured with OSHA42 compared with the impinger. The IsoChek did not detect HDI monomer, and of the three samplers analyzed by laboratories other than UNC (i.e., OSHA42, IsoChek, and WA-DOSH), the WA-DOSH was in the best agreement with the impingers. The influence of clearcoat drying time on the sampler's ability to measure monomeric and polymeric HDI emphasizes the importance of the speciation of diisocyanates in chemical analysis and the careful consideration for the selection of the air sampler to be used when measuring exposures during automotive spray painting.

Factors affecting variability in the urinary biomarker 1,6-hexamethylene diamine in workers exposed to 1,6-hexamethylene diisocyanate.

Although urinary 1,6-hexamethylene diamine (HDA) is a useful biomarker of exposure to 1,6-hexamethylene diisocyanate (HDI), a large degree of unexplained intra- and inter-individual variability exists between estimated HDI exposure and urine HDA levels. We investigated the effect of individual and workplace factors on urine HDA levels using quantitative dermal and inhalation exposure data derived from a survey of automotive spray painters exposed to HDI. Painters' dermal and breathing-zone HDI-exposures were monitored over an entire workday for up to three separate workdays, spaced approximately one month apart. One urine sample was collected before the start of work with HDI-containing paints, and multiple samples were collected throughout the workday. Using mixed effects multiple linear regression modeling, coverall use resulted in significantly lower HDA levels (p = 0.12), and weekday contributed to significant variability in HDA levels (p = 0.056). We also investigated differences in urine HDA levels stratified by dichotomous and classification covariates using analysis of variance. Use of coveralls (p = 0.05), respirator type worn (p = 0.06), smoker status (p = 0.12), paint-booth type (p = 0.02), and more than one painter at the shop (p = 0.10) were all found to significantly affect urine HDA levels adjusted for creatinine concentration. Coverall use remained significant (p = 0.10), even after adjusting for respirator type. These results indicate that the variation in urine HDA level is mainly due to workplace factors and that appropriate dermal and inhalation protection is required to prevent HDI exposure.

Development of a permeation panel to test dermal protective clothing against sprayed coatings.

OBJECTIVES: Design, construct, and characterize an apparatus to evaluate dermal protective clothing for resistance to polymerizing materials. Specifically, we evaluated the permeation of the most common glove material used in automotive collision repair (0.10-0.13 mm or 4-5 mil latex) with representative isocyanate-containing clear coats. Our ultimate goal is to make informed recommendations on dermal protective materials to prevent isocyanate exposures and reduce the likelihood of occupational illness in automotive collision repair and other industries. METHODS: A novel permeation panel was developed to assess dermal protective clothing. With this apparatus, up to eight test materials may be evaluated under typical-spray application conditions. Solid collection media comprised of 1-(2-pyridyl)-piperazine (2-PP)-coated fiberglass filters or colorimetric SWYPE™ pads were placed behind test materials to capture permeants. The 2-PP-coated filters were subsequently analyzed using a modified OSHA42/PV2034 method. Color change in the SWYPEs provided an immediate field estimate of breakthrough time. In addition, Teflon filters were mounted proximal to the permeation cells to measure the mass of clear coat applied to the panel and to evaluate loading homogeneity. This study evaluated the permeation of isocyanates through 0.10-0.13 mm latex glove material at a fixed time (30 min post-spraying) and over a time course (6-91 min post-spraying). RESULTS: Monomers 1,6-hexamethylene diisocyanate (HDI) and isophorone diisocyanate (IPDI) permeated through (0.10-0.13 mm) latex glove material under typical glove use conditions (30 min). The latex glove material exhibited immediate breakthrough, with a permeation rate of 2.9 ng min(-1) cm(-2). The oligomeric forms of HDI and IPDI did not permeate the latex glove material. The spray application at 71 ± 5 °F was fairly homogeneous (33.7 ± 8 mg weight of dry clear coat per 5 cm(2)). CONCLUSIONS: The permeation panel is a viable method to assess dermal protective clothing performance against polymerizing materials. Thin (0.10-0.13 mm) latex gloves were determined to be ineffective barriers to the isocyanates commonly found in clear coats. Because this type of glove is used frequently in auto body shops, the potential for isocyanate exposure is of concern. Permeation tests with other dermal protective clothing materials and other clear coat formulations are needed to make recommendations about alternative materials.

Occupational carbon monoxide poisoning in Washington State, 2000-2005.

Washington State workers' compensation data can be used to guide prevention efforts focused on occupational carbon monoxide (CO) poisoning. Between 2000 and 2005, a total of 345 individual claims comprising 221 different exposure incidents were identified for the 6-year time period. The construction industry had 43 (20%) CO incidents, followed by wholesale trade with 32 (15%), and agriculture with 27 (12%) incidents. Fuel-powered forklifts caused 29% of all incidents, while autos/trucks/buses were responsible for 26%. The number of forklift incidents in fruit packing and cold storage companies declined significantly from 1994 through 2007 (Spearman's rho = 0.6659, p < 0.01). While this study used multiple medical records from workers' compensation claims to identify CO poisoning, a surveillance system that lacks extensive medical records may rely principally on carboxyhemoglobin (COHb) tests. This study demonstrated that 71% of the identified workers' compensation claims had associated COHb tests. The recurrence and timing of CO poisoning as well as control of the CO-generating source were determined. Approximately 8% of all work sites had recurring CO poisoning incidents. Two percent experienced a recurrent incident within 16 days of the initial incident, and 6% experienced a recurrent incident between 16 days and 3 years after the initial incident. Sixty-seven percent of claimants exposed to CO were not in direct control of the CO-generating source; this has implications for CO prevention and underscores the need for all employees to be trained on CO hazards.

Urine 1,6-hexamethylene diamine (HDA) levels among workers exposed to 1,6-hexamethylene diisocyanate (HDI).

Urinary 1,6-hexamethylene diamine (HDA) may serve as a biomarker for systemic exposure to 1,6-hexamethylene diisocyanate (HDI) in occupationally exposed populations. However, the quantitative relationships between dermal and inhalation exposure to HDI and urine HDA levels have not been established. We measured acid-hydrolyzed urine HDA levels along with dermal and breathing-zone levels of HDI in 48 automotive spray painters. These measurements were conducted over the course of an entire workday for up to three separate workdays that were spaced approximately 1 month apart. One urine sample was collected before the start of work with HDI-containing paints and subsequent samples were collected during the workday. HDA levels varied throughout the day and ranged from nondetectable to 65.9 microg l(-1) with a geometric mean and geometric standard deviation of 0.10 microg l(-1) +/- 6.68. Dermal exposure and inhalation exposure levels, adjusted for the type of respirator worn, were both significant predictors of urine HDA levels in the linear mixed models. Creatinine was a significant covariate when used as an independent variable along with dermal and respirator-adjusted inhalation exposure. Consequently, exposure assessment models must account for the water content of a urine sample. These findings indicate that HDA exhibits a biphasic elimination pattern, with a half-life of 2.9 h for the fast elimination phase. Our results also indicate that urine HDA level is significantly associated with systemic HDI exposure through both the skin and the lungs. We conclude that urinary HDA may be used as a biomarker of exposure to HDI, but biological monitoring should be tailored to reliably capture the intermittent exposure pattern typical in this industry.

Effect of creatinine and specific gravity normalization on urinary biomarker 1,6-hexamethylene diamine.

Urine amine levels used as biomarkers of diisocyanate exposure have usually been normalized with creatinine concentration. The suitability of using creatinine concentration or specific gravity for these biomarkers in exposure assessment has not been established. We investigated the effect of creatinine concentration and specific gravity on urine 1,6-hexamethylene diamine (HDA) levels in multiple mixed linear regression models using quantitative dermal and inhalation exposure data derived from a survey of automotive spray painters occupationally exposed to 1,6-hexamethylene diisocyanate (HDI). Painters' dermal and breathing-zone HDI exposure were monitored for an entire workday for up to three workdays spaced approximately one month apart. One urine sample was collected before the start of work with HDI-containing paints, and multiple samples were collected throughout the workday. Both creatinine concentration and specific gravity were highly significant predictors (p < 0.0001) of urine HDA levels. When these two were used together in the same model, creatinine remained highly significant (p < 0.0001), but specific gravity decreased in significance (p-values 0.10-0.17). We used different individual factors to determine which affected creatinine and specific gravity. Urine collection time was a highly significant predictor of specific gravity (p = 0.003) and creatinine concentration (p = 0.001). Smoker status was significant (p = 0.026) in the creatinine model. The findings indicate that creatinine concentration is more appropriate to account for urine water content than specific gravity and that creatinine is best used as an independent variable in HDI exposure assessment models instead of traditional urine normalization with creatinine concentration.

Quantification and statistical modeling--part I: breathing-zone concentrations of monomeric and polymeric 1,6-hexamethylene diisocyanate.

We conducted a repeated exposure-assessment survey for task-based breathing-zone concentrations (BZCs) of monomeric and polymeric 1,6-hexamethylene diisocyanate (HDI) during spray painting on 47 automotive spray painters from North Carolina and Washington State. We report here the use of linear mixed modeling to identify the primary determinants of the measured BZCs. Both one-stage (N = 98 paint tasks) and two-stage (N = 198 paint tasks) filter sampling was used to measure concentrations of HDI, uretidone, biuret, and isocyanurate. The geometric mean (GM) level of isocyanurate (1410 microg m(-3)) was higher than all other analytes (i.e. GM < 7.85 microg m(-3)). The mixed models were unique to each analyte and included factors such as analyte-specific paint concentration, airflow in the paint booth, and sampler type. The effect of sampler type was corroborated by side-by-side one- and two-stage personal air sampling (N = 16 paint tasks). According to paired t-tests, significantly higher concentrations of HDI (P = 0.0363) and isocyanurate (P = 0.0035) were measured using one-stage samplers. Marginal R(2) statistics were calculated for each model; significant fixed effects were able to describe 25, 52, 54, and 20% of the variability in BZCs of HDI, uretidone, biuret, and isocyanurate, respectively. Mixed models developed in this study characterize the processes governing individual polyisocyanate BZCs. In addition, the mixed models identify ways to reduce polyisocyanate BZCs and, hence, protect painters from potential adverse health effects.

Objective color scale for the SWYPE surface sampling technique using computerized image analysis tools.

Colorimetric SWYPE pads are useful tools for identifying unpolymerized aliphatic isocyanates on a variety of surfaces. This technique has been used in autobody shops to determine the presence of hexamethylene diisocyanate and other aliphatic isocyanates that are important constituents of many automotive coatings. SWYPEs have the advantage of being relatively inexpensive, rapid, and portable. The color change elicited by aliphatic isocyanates (from yellow to red) provides a visual indication of the extent of surface contamination. To quantify isocyanate contamination based on the colorimetric response, an objective color scale was developed for isocyanate loading. Sampled pads were digitized on a calibrated, portable flatbed scanner, and red-green-blue (RGB) histograms of SWYPE images were created. A calibration curve was created from a series of reference images derived from SWYPEs loaded with an isocyanate-containing product. The SWYPE RGB analysis allowed for quantification over a range of isocyanate loadings: from approximately 0.01 to 24.0 microg/cm(2), with reproducibility of >90%, accuracy >90%, and a surface extraction efficiency of >90%. RGB analysis exhibited a lower detection limit than visual scoring (approximately 3 microg versus approximately 10 microg). The colorimetric response was cross validated with a high-performance liquid chromatography quantitative assay. When combined with RGB analysis, SWYPE colorimetric wipes represent a rapid and inexpensive method to assess objectively surface contamination with aliphatic isocyanates.