Human biomonitoring of aluminium after a single, controlled manual metal arc inert gas welding process of an aluminium-containing worksheet in nonwelders.

PURPOSE: Several existing field studies evaluate aluminium welding works but no thoroughly controlled exposure scenario for welding fume has been described yet. This study provides information about the uptake and elimination of aluminium from welding fumes under controlled conditions. METHODS: In the Aachen Workplace Simulation Laboratory, we are able to generate welding fumes of a defined particle mass concentration. We exposed 12, until then occupationally unexposed participants with aluminium-containing welding fumes of a metal inert gas (MIG) welding process of a total dust mass concentration of 2.5 mg/m(3) for 6 h. Room air filter samples were collected, and the aluminium concentration in air derived. Urine and plasma samples were collected directly before and after the 6-h lasting exposure, as well as after 1 and 7 days. Human biomonitoring methods were used to determine the aluminium content of the samples with high-resolution continuum source atomic absorption spectrometry. RESULTS: Urinary aluminium concentrations showed significant changes after exposure compared to preexposure levels (mean t(1) (0 h) 13.5 µg/L; mean t(2) (6 h) 23.5 µg/L). Plasma results showed the same pattern but pre-post comparison did not reach significance. CONCLUSIONS: We were able to detect a significant increase of the internal aluminium burden of a single MIG aluminium welding process in urine, while plasma failed significance. Biphasic elimination kinetic can be observed. The German BAT of 60 µg/g creatinine was not exceeded, and urinary aluminium returned nearly to baseline concentrations after 7 days.

Effects of Overlap Between Consecutive Words on Speeded Typing Inform About Representation of Serial Order Within Words.

Typing is an everyday activity that requires people to use the correct serial order of phonological and orthographic forms of words. The evidence until now shows that different forms of representation of serial order have mixed contributions to typing performance. It is not clear whether and how representational overlap between subsequent words impacts the speed of typing. In three experiments, we used speeded typing of six-letter words. Including conditions with secondary task load to counteract potential ceiling effects, we varied whether subsequent words had partial overlap with respect to a chaining representation (e.g., kirsch → schaum; same triplet in different position) or, in addition, overlapped with respect to a potential positional representation (e.g., berlin → dublin, same triplet in the same position). Differently from previous findings (e.g., Snyder & Logan, 2014), Experiments 1 and 2 suggest that (a) chaining as well as positional coding are involved as representations of serial order and (b) partial overlap of representation of serial order leads to costs in typing speed. Experiment 3 demonstrated that full overlap speeds up typing. Across all experiments, the overlap effects were most revealed in the latency of the first keystroke, indicating the planning of motor programs. Taken together, the results suggest that even in highly practiced tasks such as typing, the activation of representations of serial order has side effects beyond the production of the current sequence.

Single and Combined Exposure to Zinc- and Copper-Containing Welding Fumes Lead to Asymptomatic Systemic Inflammation.

OBJECTIVE: Recently, it has been shown that exposure to welding fumes containing both zinc and copper leads to asymptomatic systemic inflammation in humans as shown by an increase of blood C-reactive protein. In the present study, it was investigated which metal is responsible for this effect. METHODS: Fifteen healthy male subjects were exposed under controlled conditions to welding fumes containing either zinc, or copper, or copper and zinc. RESULTS: For each exposure blood C-reactive protein increased. CONCLUSIONS: Copper- and zinc-containing welding fumes are able to induce systemic inflammation.

Assessment of the Biological Effects of Welding Fumes Emitted From Metal Active Gas and Manual Metal Arc Welding in Humans.

OBJECTIVE: Emissions from a particular welding process, metal inert gas brazing of zinc-coated steel, induce an increase in C-reactive protein. In this study, it was investigated whether inflammatory effects could also be observed for other welding procedures. METHODS: Twelve male subjects were separately exposed to (1) manual metal arc welding fumes, (2) filtered air, and (3) metal active gas welding fumes for 6 hours. Inflammatory markers were measured in serum before, and directly, 1 and 7 days after exposure. RESULTS: Although C-reactive protein concentrations remained unchanged, neutrophil concentrations increased directly after exposure to manual metal arc welding fumes, and endothelin-1 concentrations increased directly and 24 hours after exposure. After exposure to metal active gas and filtered air, endothelin-1 concentrations decreased. CONCLUSIONS: The increase in the concentrations of neutrophils and endothelin-1 may characterize a subclinical inflammatory reaction, whereas the decrease of endothelin-1 may indicate stress reduction.