ABSTRACT
Welding fumes were reclassified as a Group 1 carcinogen by the International Agency for Research on Cancer in 2017. Gas metal arc welding (GMAW) is a process widely used in industry. Fume generated from GMAW-mild steel (MS) is abundant in iron with some manganese, while GMAW-stainless steel (SS) fume also contains significant amounts of chromium and nickel, known carcinogenic metals. It has been shown that exposure to GMAW-SS fume in A/J mice promotes lung tumors. The objective was to determine if GMAW-MS fume, which lacks known carcinogenic metals, also promotes lung tumors in mice. Male A/J mice received a single intraperitoneal injection of corn oil or the initiator 3-methylcholanthrene (MCA; 10 µg/g) and, one week later, were exposed by whole-body inhalation to GMAW-MS aerosols for 4 hours/day x 4 days/week x 8 weeks at a mean concentration of 34.5 mg/m3. Lung nodules were enumerated by gross examination at 30 weeks post-initiation. GMAW-MS fume significantly increased lung tumor multiplicity in mice initiated with MCA (21.86 ± 1.50) compared to MCA/air-exposed mice (8.34 ± 0.59). Histopathological analysis confirmed these findings and also revealed an absence of inflammation. Bronchoalveolar lavage analysis also indicated a lack of lung inflammation and toxicity after short-term inhalation exposure to GMAW-MS fume. In conclusion, this study demonstrates that inhalation of GMAW-MS fume promotes lung tumors in vivo and aligns with epidemiologic evidence that shows MS welders, despite less exposure to carcinogenic metals, are at an increased risk for lung cancer.
Subject(s)
Air Pollutants, Occupational/toxicity , Carcinogens/toxicity , Iron/toxicity , Lung Neoplasms/chemically induced , Steel , Welding , Administration, Inhalation , Animals , Lung Neoplasms/pathology , Male , MiceABSTRACT
BACKGROUND: Heart rate and cardiovascular function are regulated by the autonomic nervous system. Heart rate variability (HRV) as a marker reflects the activity of autonomic nervous system. The prognostic significance of HRV in cardiovascular disease has been reported in clinical and epidemiological studies. The present study focused on the influence of inhaled multi-walled carbon nanotubes (MWCNTs) on autonomic nervous system by HRV analysis. METHODS: Male Sprague-Dawley rats were pre-implanted with a telemetry device and kept in the individual cages for recovery. At week four after device implantation, rats were exposed to MWCNTs for 5 h at a concentration of 5 mg/m(3). The real-time EKGs were recorded by a telemetry system at pre-exposure, during exposure, 1 day and 7 days post-exposure. HRV was measured by root mean square of successive differences (RMSSD); the standard deviation of inter-beat (RR) interval (SDNN); the percentage of successive RR interval differences greater than 5 ms (pNN5) and 10 ms (pNN10); low frequency (LF) and high frequency (HF). RESULTS: Exposure to MWCNTs increased the percentage of differences between adjacent R-R intervals over 10 ms (pNN10) (p < 0.01), RMSSD (p < 0.01), LF (p < 0.05) and HF (p < 0.01). CONCLUSIONS: Inhalation of MWCNTs significantly alters the balance between sympathetic and parasympathetic nervous system. Whether such transient alterations in autonomic nervous performance would alter cardiovascular function and raise the risk of cardiovascular events in people with pre-existing cardiovascular conditions warrants further study.
Subject(s)
Arrhythmias, Cardiac/chemically induced , Autonomic Nervous System/drug effects , Cardiovascular System/drug effects , Heart Rate/drug effects , Nanotubes, Carbon/toxicity , Administration, Inhalation , Animals , Arrhythmias, Cardiac/physiopathology , Autonomic Nervous System/physiopathology , Cardiovascular System/innervation , Electrocardiography, Ambulatory , Male , Rats, Sprague-Dawley , Risk Assessment , Telemetry , Time FactorsABSTRACT
The health care industry has experienced some turbulent years recently, and the end does not seem near. Payment methods are being established that are entirely new and have not stood the test of time. For hospitals to remain competitive, they must be able to understand and master the different payment methods. The one common thread discussed throughout this article is that intelligent decisions concerning payment cannot be made until the costs are known. Hospitals cannot commit to these contracts and cannot expect to perform well and generate profits without this knowledge--without detailed cost information, it is a "stab in the dark." A good working relationship between cost accounting and materiel management is needed to accumulate timely and accurate information. This is why their relationship is so important. Those hospitals that master this information requirement will have the best chance of survival in the increasingly competitive field of health care.
