A long auditory stimulus elicits a magnetic evoked response in the human brain, consisting of transient deflections followed by a sustained response. The distributions of the magnetic fields indicate that the auditory evoked transient response at a latency of 100 ms as well as the auditory sustained response are generated at and around the primary auditory cortex.

The magnetic method of measuring the amount of lung retained contaminants as well as urinary chromium and nickel determinations have been performed among 83 stainless steel (SS) welders who have used manual metal arc (MMA) and tungsten inert gas (TIG) welding techniques. The welders were divided into four groups according to the time percentage used for MMA welding. Only exposure to MMA/SS welding fumes resulted in clearly elevated chromium concentrations in the urine, the correlation coefficient between the values of urinary chromium and MMA/SS percentage being very significant (p less than 0.001). Among the smokers the urinary chromium values were increased (p less than 0.05) perhaps owing to contaminated cigarettes. In many workplaces the urinary chromium values of several welders exceeded the value of 30 microgram/l which is the recommended reference value in Finland. Owing to the solubility properties of nickel compounds in SS welding fumes urinary nickel concentrations were only slightly elevated among MMA/SS welders, and therefore, the urinary nickel determinations do not reflect the level of exposure to nickel compounds. The measured average remanent magnetic field of the chest area correlated well (p less than 0.01) with the use of the MMA technique. A very significant correlation (p less than 0.001) existed between the average remanent magnetic fields of the chest and the urinary chromium values of MMA/ss welders.

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A system for balancing superconducting gradiometric magnetometers and equipment for ppm-level testing of the balance in a laboratory are described

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