49 Exposure Assessment and Health Surveys at Metal Additive Manufacturing Facilities

Abstract Additive manufacturing (AM) is the process of building parts from 3D model data by joining materials. AM includes different techniques, such as binder jetting and powder bed fusion which uses metal powder as feedstock. Knowledge regarding exposure-related health risks in metal AM environments is still limited. Herein, we report emission data from 8 different AM companies along with health examinations of 39 controls and 48 additive manufacturing machine users (AMMU). Exposure assessment of dust and metals was performed through stationary and personal sampling of total and inhalable dust followed by metal analysis by ICP-MS. Two handheld particle-counting instruments, Lighthouse 3016-IAQ (0.3-10 µm) and Philips Aerasense NanoTracer (10-300 nm), were used to identify dusty work tasks and thereby to help prioritize preventive measures. Health examinations consisted of questionnaires, spirometry, blood sampling after a workweek and collection of urine samples before and after a workweek. Clinical markers in urine (α1-microglobulin) and plasma (ASAT, ALAT, ALP, ApoA-1, ApoB, SAA1/PON1), and urinary metal levels were analyzed. Results: Daily averages of dust and metal exposure were in general low compared to Swedish occupational exposure limits. However, particle counting instruments identified specific work tasks with high exposure risk. Mann Whitney U-test indicated statistical differences between exposed and controls for three clinical markers; ASAT and ApoA-1 in plasma as well as α-1-microglobulin in urine. There were no significant increase in exposure markers Monday to Friday nor between AMMU and controls at a group level. Although high exposure levels were seen in some individuals.