No 6 (2020)

Outbred white female rats were exposed to an aerosol of lead oxide nanoparticles in a nose-only inhalation setup at an average concentration of 1.30 ± 0.10 mg / m3 during 5 days for 4 hours a day. In parallel, the control group of rats was subjected to sham exposure under similar conditions. The deposition of nanoparticles in the lungs and in the olfactory region of the brain was detected using transmission electron microscopy. Some disorders of the body state were detected in the exposed group, some of which can be considered as the result of a lead-specific toxic effect (an increase in the proportion of reticulocytes and in urinary excretion of δ-aminolevulinic acid), and others - the result of nanoparticles circumventing the blood-brain barrier (axon demyelination, vacuolization of the neurons’ cytoplasm).

The results of our own and foreign studies have shown the absence of sensitizing properties of terephthalic acid, and therefore there was a need to review the current hygienic standard – MAC – in the air of the working area and change the hazard class of the substance. The materials of the German Research Community (DFG) were used for substantiation of MAC. Recommended MAC in the air of working area is set at 5 mg/m3 (maximum single), a mixture of vapors and aerosol, hazard class 3.

The factor limiting the tolerance of personal respiratory protection equipment should be considered the frequency of respiratory movements, which reflexively changes when additional respiratory resistance occurs. Unfortunately, there is almost no information in the available literature about changes in the tolerability of personal respiratory protection equipment at different rates of respiratory movements. The purpose of this work was to study the tolerability of personal respiratory protection equipment when changing the frequency of respiratory movements.

The study was conducted on practically healthy persons of both sexes (78 people), aged from 20 to 36 years. To simulate the conditions for the use of personal respiratory protection equipment, inspiratory resistive respiratory loads of 20% of the maximum intraoral pressure during the Mueller test were used. The tolerance of personal respiratory protection equipment was assessed using the Borg visual analogue of dyspnea scale, which reflected the level of subjective discomfort that occurs when additional respiratory resistance is turned on. During the action of additional respiratory resistance, the persons were asked to hold the frequency of respiratory movements, which was set using a special setting.

An increase in the rate of respiratory movements against the background of additional respiratory resistance leads to a significant deterioration in the objective and subjective indicators of the functional state of the persons; replacing the inhaled air with an oxygen-rich respiratory mixture with carbon dioxide absorption did not lead to a significant improvement in the functional state. A moderate decrease (up to 70% of the initial frequency of respiratory movements) in the rate of respiration leads to an improvement in the indicators of adaptive activity in conditions of additional respiratory resistance. A significant decrease (up to 35% of the initial frequency of respiratory movements) in the rate of respiration under conditions of additional respiratory resistance leads to a deterioration of objective and subjective indicators of the functional state of the subjects.

An increase in peak respiratory flow rates caused by an increase in the rate of respiration, in accordance with the well – known Rohrer equation, significantly increases inelastic resistance and, as a result, respiratory needs. These needs can be met at some time due to a significant increase in the work of the respiratory muscles, but due to fatigue of the latter, psychoemotional tension increases quite quickly and the use of personal respiratory protection equipment is abandoned.

Quetiapine is a psychotropic drug, a dibenzothiazepine derivative and a representative of the class of neuroleptics (antipsychotic drugs) of a new subgroup – atypical antipsychotic drugs («second-generation antipsychotics»). Quetiapine fumarate belongs to the 3rd hazard class in terms of DL50 when administered in the stomach according to GOST 12.1.007-76 (DL50 1380-1680 mg/kg, mice and rats), has a local irritant effect: pronounced - on the mucous membrane of the eyes and moderately pronounced - on the skin. There are no signs of skin resorptive or cumulative effects of quetiapine fumarate. When inhaled, an aerosol of quetiapine fumarate has a general toxic and irritating effect in rats. The threshold of acute inhalation action of quetiapine fumarate is set at 6,2 mg/m3 for general toxic effect (effect on the quantitative composition of peripheral blood and the cardiovascular system) and irritating effect on the mucous membranes of the upper respiratory tract. For quetiapine fumarate, the tentative safe exposure level in the air of the working area is recommended at 0,2 mg/m3 , aerosol, with «+» - special protection of the skin and eyes is required. The tentative safe exposure level in the atmospheric air of urban and rural settlements is 0,002 mg/m3.