Attenuation of subchronic formaldehyde inhalation toxicity with oral administration of glutamate, glycine and methionine.

Inhalation exposure of outbred female white rats (initial age about 4 months) to formaldehyde vapours (12.8 ± 0.69 mg/m(3)) 4h per day, 5 days per week during 10 weeks induced statistically significant changes in some indices characterizing differential WBC count, functional status of the central nervous system and liver, redox and porphyrin metabolisms, bone marrow micronuclei count as well as free amino acid spectrum of the blood serum. The development of intoxication was accompanied by increased urinary excretion of formaldehyde, formic acid and methanol. Daily oral administration of glutamate (150-180 mg), glycine (12 mg) and methionine (50mg) in combination rendered all of the formaldehyde's toxic effects reduced. This administration also caused a significant increase in the ratio between the rates of excretion of formic acid and non-metabolized formaldehyde. This shift supposedly reflects activation of oxidative detoxifying biotransformation of formaldehyde. Taking into consideration that the combination of amino acids used in this study proved innocuous in protectively effective doses, the administration in this combination may be recommended to humans exposed to high levels of formaldehyde in workplace or ambient air.

Regular variations of the mercury concentration in natural gas.

Direct on-line measurements of the mercury (Hg) content in natural gases by a newly developed Zeeman atomic absorption spectrometer RA-915+ have revealed a short-term variability of the Hg concentration, which has not earlier been known. The significant variability of the mercury concentration in a hydrocarbon gas was found in all of the gas wells studied. The variation magnitudes range from 10 to 80% of the average mercury content in the gas. The fluctuations have regular components with periods from few minutes to several hours and can be represented as a set of harmonics with different spectral intensity and stability in time. The most stable harmonics are characterised by intermediate frequencies with periods of 0.3-2.5 h. These 'basic' frequencies are characteristic of individual gas wells even within a single productive horizon. The remarkable features of these harmonics are the multiplicity of their periods and good agreement with phases of the Earth's own oscillations. A relatively low-frequency oscillation with a period of 25 h corresponds to a lunar tidal cycle. An oscillatory mechanism of the adsorption-desorption of mercury in a porous gas-bearing medium is assumed to be responsible for these effects.