Exposure Risk Assessment: Production to Pressroom
Natasha Hausler Banke, PhD, INX International Ink Company
Systems employed to improve and protect human health and the environment, the Globally Harmonized System of Classification and Labelling of Chemicals, by the United Nations, (GHS) and REACH, regulations adopted by European Union, have changed the hazard classifications of many chemicals and commonly used UV printing raw materials. The changing reclassifications required and continues to require ink manufacturers to reevaluate ink formulations as well as revisit the safety of use and exposure to employees, customers, and consumers.
In response to reclassifications, INX chose to study the actual exposure of a common photoinitiator which was reclassified by REACH committee of the European Chemicals Agency (ECHA) as toxic for reproduction, Category 1B (H360D; may damage the unborn child). The photoinitiator, 2-Benzyl-2-(dimethylamino)-1-[4-(4-morpholinyl)phenyl]-1-butanone (PI 369), was reclassified from Repr. 2 H361 to Repr. 1B H360d, meaning exposure is a concern for pregnant female workers. The ECHA scientific overview for PI369 identified the no observed adverse effect level (NOAEL) to be 100 mg/kg body weight/day. Additionally, subsequent toxicology report commissioned by INX EHS department concluded that the level of reasonable certainty of no harm to be 0.330 mg/kg body weight/ day. Reclassification of chemicals falls within the scope of the European Packaging Ink Association (EUPIA) Exclusion Policy. Subsequently, PI369 was added to the list. The Exclusion Policy states that “substances and mixtures in stated hazard classes are excluded as raw materials for the manufacture of printing inks”. The Exclusion Policy is largely based on hazard classification as opposed to risk assessment studies which would detail actual daily exposure. Recent reclassification of PI369 required EUPIA member companies six months to reformulate away from PI369 (starting March 22, 2018) (ECHA, Committee for Risk Assessment, Annex 1, 2016).
The purpose of this study was to determine the actual risk-based exposure to the common PI over the course of an 8-hour period. To determine the actual exposure-based risk of PI369, an air quality trial was undertaken to evaluate and quantify the exposure of PI369 to individuals handling it and/or working in a facility where it is used. Knowing the NOAEL and the reasonable certainty level of no harm, allows for direct comparisons of exposure in a “real-world” risk assessment study in an ink production facility and pressroom.
The risk assessment was a coordinated effort between INX Environmental Health and Safety, INX R&D Analytical, and INX R&D Energy Curable labs. Active air sampling pumps were used to collect and test for PI369 in each of three arms of this study. The first arm of the project assessed air quality in at various locations in an ink production facility to examine air quality where the PI is used. The second arm of the study was to provide proof of concept for testing the air quality in a pressroom. A press trial simulation was run using an inkometer to create misting of UV ink and the air quality was assessed and analyzed for the PI. The pressroom trial was the third arm of the project to assess the risk of exposure to pressroom workers. In the pressroom trial, active sample pumps were set up at various locations around a press—near the ink rollers, expected to be a worst-case exposure area as well as by the control booth, expected to be the area of least exposure. In each arm of the study, areas of the worst (highest) exposure and least exposure were identified.
The air filters were extracted and subsequently quantified for PI369 content by liquid chromatography tandem mass spectrometry. The analysis was consistent with quantitation and validation methods criteria set forth by the USFDA. At constant flow through the filter, the analysis revealed that the filter with the highest content of IPI369, or worst-case exposure where the filter was located near the rollers, to be 0.77 microgram/ kg body weight/ day (0.23% of the level of reasonable certainty of no harm. Adjusting for the number of breaths a person takes during moderate activity, the amount of PI369 detected on the filter does not exceed 5% (16.5 microgram/ kg body weight/ day) of the level of reasonable certainty of no harm, which is less than 0.02% (20 microgram/ kg body weight/ day) of the NOAEL.
This technical paper is the culmination of the three projects which provides data for the current risk assessment of PI369. Equally important, this study provides a framework for future exposure testing for other chemicals. Additionally, risk-based assessments provide better information to companies for requirements of personal protective equipment (PPE). Global markets for chemicals and raw materials in ink manufacturing is continuously changing. Following an explosion at a chemical plant in March 2019, the production of key intermediates and photoinitiators is expected to be affected due to efforts by the Chinese government to improve safety conditions (Bloomberg, 2019). The ability of ink manufacturers to make production and formulation decisions based on the actual risk to employees and customers, as opposed to making decisions based on perceived risk or hazard, can potentially allow for more efficient allocation of scarce materials. As the global supply of raw materials change and safety and toxicology data become available, it is becoming more important to determine actual exposure and risk, determine and create benchmarks for exposure.