Abstract No:
1419
Abstract Type:
Professional Poster
Authors:
Y Suzuki1
Institutions:
1SIBATA Scientifc Technology Ltd., Soka City, JPN
Presenter:
Yoshihiro Suzuki
SIBATA Scientifc Technology Ltd.
Description:
This study reports on the development of a personal sampler for measuring isocyanurate exposure during the spray painting of urethane coatings. The sampler is designed with a simple structure to simultaneously collect both aerosolized mist and gaseous isocyanates from the sprayed paint. This report validates the sampler through spiking and recovery tests, as well as collection tests, in an actual manufacturing environment.
Situation / Problem:
In custom vehicle manufacturing (such as trucks, fire engines, and airport vehicles) and architectural insulation, spray painting with urethane coatings is a common practice. A significant health concern exists for workers exposed to isocyanates during these applications. Historically, highly toxic isocyanates like TDI and MDI have been managed with strict personal exposure limits (TWA-TLV: 0.005 ppm). However, urethane spray painting often uses polyisocyanurates, such as HMDI, which are aliphatic isocyanates with multiple bonds. This widespread use is based on older reports suggesting that aliphatic isocyanates and their copolymers have low toxicity. However, there have been increasing opinions that even low-volatility, low-reactivity substances like isocyanurates should be considered with a similar risk profile to TDI and MDI as asthma sensitizers.
Given the diverse exposure scenarios of various isocyanates, the EU Directive 2024/869 recently established new total isocyanate exposure limits (TWA 10 µg NCO/m³, and from January 1, 2029, 6 µg NCO/m³). To understand and mitigate worker risk, it's essential to increase the number of measurements and gain more knowledge about these exposure levels. Existing sampling methods for diverse isocyanates, such as isocyanurates, include the robust but cumbersome combined liquid and filter collection method of ISO 16702, and the sophisticated and expensive denuder-filter sampler described in ISO 17734-1.
Methods:
We hypothesized that developing a simpler isocyanate sampler is necessary to increase the number of measurements and thereby expand our understanding of occupational exposure.
Our simplified sampler design was developed with reference to ISO 17734-1. The prototype consists of a plastic syringe barrel containing a glass fiber filter impregnated with acidic dibutylamine (DBA), followed by a layer of silica gel. This two-layer structure was chosen because dry samplers using only a filter may allow coarse particles (mist > 2 µm) to pass through. The combination with DBA-impregnated silica gel ensures comprehensive collection. (Note: We assumed the reaction between silica gel and DBA is minimal (Lewis acid-base reaction) and does not occur at room temperature without a catalyst.)
We conducted recovery tests for the prototype sampler using an isocyanurate monomer standard. A controlled flow of clean air was passed through the sampler for a set period, and the collected isocyanates were then desorbed with acetonitrile for analysis. We used an LC/MS method (Acquity QDa, Waters) for isocyanurate analysis (m/z 892), with dibutylaniline (DBAn: m/z 150) as the internal standard to reduce analytical costs. Currently, we are using this prototype sampler to conduct personal exposure measurements during the urethane painting process for custom vehicles.
Results / Conclusions:
The recovery rates for isocyanurate from the spiking tests were excellent, ranging from 95-100% (n=4), and derivatization with DBA was successful. The internal standard, DBAn, showed good separation and sensitivity under our LC/MS conditions, posing no issues for isocyanurate analysis. This research is ongoing. At the time of this presentation, we plan to report results from several painting sites, comparing our new method to conventional methods.
Core Competencies:
Chemical Sampling and Instrumental Analysis
Secondary Core Competencies:
Chemical Hazards
Total Worker Health ®
Choose at least one (1), and up to five, (5) keywords from the following list. These selections will optimize your presentation's search results for attendees.
Aerosol and airborne particulate monitoring
Exposure Assessment
Gas and vapor detection
Risk assessment and management
Toxicology
Based on the selected primary competency area of your proposal, select one group below that would be best suited to serve as a subject matter expert for peer review:
(Select one)
Sampling and Laboratory Analysis Committee
Based on the information that will be presented during your proposed session, please indicate the targeted audience practice level: (select one)
Practitioner: Practitioner is a job title given to persons in various occupational fields who are trained to assist professionals but are not themselves licensed or certified at a professional level by a certification body recognized by the National Accreditation Recognition (NAR) Committee of IOHA. The IH/OH practitioner performs tasks requiring significant knowledge and skill in the IH/OH field, such as conducting worker exposure monitoring and, in some cases, may even function independently of a professional IH/OH but may not be involved in the breadth of IH/OH practice nor have the level of responsibility of a professional IH/OH certified by examination.
The IH/OH practitioner requires a certain level of education that can be obtained from an accredited university or equivalent. Additional training in specific skill sets that provide additional career paths to the IH/OH practitioner can also be obtained. IH/OH practitioners may also serve as team leaders or project managers.
Was this session organized by an AIHA Technical Committee, Special Interest Group, Working Group, Advisory Group or other AIHA project Team?
No
Are worker exposure data and/or results of worker exposure data analysis presented?
No
How will this help advance the science of IH/OH?
This study will provide necessary information to understand the health of workers involved in urethane spray painting work, and will also enable OH to properly consider the occupational risks of targeted chemicals for painters.
What level would you consider your presentation content geared towards?
Intermediate: Specific topics within a subject. The participant would have two (2) to ten (10) years experience in industrial hygiene or OEHS and a good understanding of the subject area, but not of the specific topic presented. Prerequisites required: another course, skill, or working knowledge of the general subject.
Have you presented this information before?
No
I have read and agree to these guidelines.
Yes