The role of home smoking bans in limiting exposure to secondhand tobacco smoke in Hungary.

Our objective was to assess how exposure to secondhand tobacco smoke occurs in Hungarian homes, particularly among non-smokers, and to examine the effectiveness of home smoking bans in eliminating exposure to secondhand smoke at home. In 2009, 2286 non-smokers and smokers aged 16-70 years, who were selected randomly from a nationally representative sample of 48 Hungarian settlements, completed paper-and-pencil self-administered questionnaires addressing tobacco-related attitudes, opinions and behaviors. Chi-square tests, one-way analysis of variance and multivariate logistic regression models were used to assess the effect of demographics, socio-economic characteristics and home smoking policies on the risk of exposure to secondhand tobacco smoke at home. Significantly higher risk of exposure was found among younger, lower educated and poorer people and among those having no or partial home smoking restrictions. There was a significant interaction between education level and home smoking policies: the effect of a smoking ban on exposure to secondhand tobacco smoke was stronger for the lower educated group than the higher educated group. The results suggest that Hungarians are making good progress in implementing home smoking bans, and that in the majority of population these bans are working. More can be done to promote the uptake of home smoking bans among poorer and less educated subpopulations.

A study on immunotoxicological effects of subacute amitraz exposure in rats.

The effects of amitraz, a formamidine pesticide, were investigated in four-week old outbred male Wistar rats on certain classic toxicological and haematological parameters as well as on specific immune functions. The animals were treated, per os by gavage for 28 days, in a five-day treatment two days break system, with 26.5, 21.1, 10.6 and 5.29 mg/kg/day amitraz. On the 29th day, organ weights of the thymus, heart, lung, spleen, liver, kidneys, adrenals, testicles and popliteal lymph node; WBC and RBC counts, Ht, MCV, haemoglobin; and cell content of the femoral bone marrow were determined. In two separate groups, the effects of amitraz on the PFC content of the spleen, and on the maximum level and time course of DTH reaction, were investigated. Amitraz in 26.5 mg/kg dose increased relative adrenal weight, and decreased relative liver weight, MCV value, PFC content of the spleen, and the maximum level of DTH reaction. The 21.1 mg/kg dose decreased only MCV value, while 10.6 mg/kg elevated the liver-to-brain weight ratio. Based of these findings, a NOEL dose of 5.29 mg/kg was determined for amitraz in this experimental system; while the LOEL doses were 10.6 mg/kg for the general toxicological, 21.1 mg/kg for the haematological and 26.5 mg/kg for the immune function parameters. The results show that the exposure sensitivity of these immune functions to amitraz is lower than that of some other toxicological and haematological parameters.

Immunotoxicological investigation of subacute combined exposure with low doses of Pb, Hg and Cd in rats.

Detectable interactions between NOEL (No Observed Effect Level) doses of Pb, Hg and Cd in general toxicological, hematological, and immune function parameters were investigated. The metals (Pb-acetate, 20 mg/kg; HgCl2, 0.40 mg/kg; CdCl2, 1.61 mg/kg) were combined. First, the rats received the combination Pb + Hg + Cd for 4 weeks per os. Significant difference vs. control was found only in the weight of lung and popliteal lymph node (PLN). The Pb + Hg and Pb + Cd combinations significantly decreased the PLN to 100 g body weight and PLN to brain weight ratio, and Pb+Hg also decreased the relative adrenal weight. After 12 weeks treatment with the same doses, effects on the thymus, kidney, and adrenal weights in the Pb + Hg, and thymus weight in the Pb + Cd, combination were seen. Pb + Cd also affected the white and red blood cell count and hematocrit. Combined with Hg or Cd, NOEL dose Pb showed toxicity, indicating that exposure limits may be inefficient in combined exposure situations.

Stimulus frequency dependence of the central and peripheral somatosensory evoked activity in rats treated with various pesticides.

Rats were treated with a combination of insecticide agents in different timing schemes. In acute administration, 1/5 LD50 of the three insecticides: dimethoate, propoxur and cypermethrin, or their combination, was given once by gavage. In the developmental model, female rats received oral doses of 1/25 LD50 of the above insecticides in combination in three timing schemes including pregnancy and lactation. Responses in the somatosensory cortex and in the tail nerve, evoked by peripheral electric stimulation, were recorded in acute preparation under urethane anesthesia. It was tested whether the parameters of the cortical and peripheral evoked response are dependent on the frequency and whether this dependence is different in control and treated animals. The latency increase of the cortical responses with increasing stimulation frequency was significantly stronger in rats treated acutely with cypermethrin and the combination, and in rats receiving the combination during both intra- and extrauterine development. On the duration, the effects were less clear. Frequency dependent increase of the tail nerve action potential latency was significantly intensified by cypermethrin, and the amplitude decrease, by cypermethrin and dimethoate. Fatigue of this response during a stimulation series was also altered by the insecticides. Frequency dependence and fatigue possibly reflect the actual state of the nervous system and may have the potency to be developed to functional biomarkers.

Neurotoxicologic investigations of the pesticide dichlorvos (DDVP). Effects on the central and peripheral nervous system.

The neurotoxic effect on the central and peripheral nervous system of dichlorvos (DDVP) was investigated by a computer system in acute and subchronic experiments in CFY male rats. The administered peroral doses were given by gavage; the acute group was given a single 88 mg/kg dose and the 2 subchronic groups were given 1.6 mg/kg or 0.8 mg/kg daily for a period of 6 weeks. Significant changes of the function of CNS - increase of EEG mean frequency, decrease of EEG mean amplitude, that of activity of EEG bands (power density) - and peripheral nervous system - decrease of conduction velocity, increase of relative and absolute refractory periods - were found after treatment with both the single large and repeated small doses of dichlorvos. There were no correlations between the functional disturbances of the central and peripheral nervous systems and the inhibition of the cholinesterase activity in various organs and the blood.

Electrocorticogram changes caused by subchronic lead treatment of rats.

Male Wistar rats were treated per os through gavage for 4, 8 and 12 weeks by 80.0, 160.0 and 320.0 mg/kg lead in form of lead acetate. The changes of certain parameters (mean frequency, mean amplitude, ECoG index-the ratio of the slow and fast bands, power spectrum of the frequency bands) of the electrocorticogram (ECoG) recorded from the primary somatosensory, visual and auditory centres of anaesthetized rats were analysed. The data show that all investigated parameters had dose- and time-dependent changes: increased mean frequencies accompanied by decreased mean amplitudes and ECoG-indices. These changes were significant only at the highest, or at the two higher dose groups by the end of the experiment. The data suggest that subchronic, low-level exposure of lead can affect the integrated electrophysiological function of the brain.

Effect of subchronic mercury exposure on electrocorticogram of rats.

Mercury is a neurotoxic compound causing irreversible disorders of the central and peripheral nervous system. In some of the previous human and experimental studies mercury also affected some functional neurological parameters such as EEG, and cortical evoked potentials. In the present study, the effect of subchronic (4, 8, and 12 weeks) relatively low-level (0.4, 0.8, and 1.6 mg/kg mercury in form of HgCl2, per os by gavage) treatment on the basic cortical activity was investigated. Certain parameters of electrocorticogram (ECoG) recorded simultaneously from the primary somatosensory, visual and auditory centres were analyzed. The results showed that mercury had a dose- and time-dependent effect on the examined ECoG parameters, and the changes became significant by the end of the experiment of week 12.

EEG changes caused by dimethoate treatment in three generations of rats.

Wistar rats were continuously treated with 7.0, 10.5, 14.0, 28.0 mg/kg (1/100, 1/75, 1/50 and 1/25 LD50) of dimethoate per os including the pregnancy of dams and the lactation period of pups as well as in adulthood for three subsequent generations. The EEG of male rats of each generation was recorded at the age of 12-13 weeks. The mean frequency, mean amplitude, EEG index and the power spectrum were analysed. The data showed that the overall EEG activity of the treated rats was greater than of the controls. The mean frequency was higher, the mean amplitude and the EEG index were lower, the activity of the lower frequency wave bands decreased, that of the higher frequency wave bands increased. The changes of the mentioned EEG parameters were most pronounced in the third generation.

Changes of brain evoked potentials caused by dimethoate treatment in three generations of rats.

Wistar rats were continuously treated with 7.0, 10.5, 14.0, and 28.0 mg/kg (1/100, 1/70, 1/50 and 1/25 LD50) of dimethoate per os including the pregnancy and lactation periods for three subsequent generations. The somatosensory, visual and auditory evoked brain potentials of male rats of each generation were registered at the age of 12-13 weeks with silver electrodes placed on the primary somatosensory, visual and auditory cortex. The measured parameters were the latency and duration of the evoked potentials. There were differences in the changes among the various evoked potentials in all of the generations. The strongest effect caused by dimethoate was seen in the case of the somatosensory evoked potentials compared to the control. The changes of the visual and auditory evoked potentials were milder. Comparing the changes of the evoked potentials of the three generations it was found that there were no significant changes between the data of the three populations.

Experimental model studies of pesticide exposure.

The neurotoxic effects of Dimethoate (Dim), Dichlorvos (DDVP) and Methyl-Parathion (MP) respectively were investigated on the central nervous system (CNS) and peripheral nervous system (PNS) of rats after different treatment schedules at the macro and single unit cell level. At the macro investigations 1/25, 1/50 and 1/100 of the respective LD50 values of each pesticide were administered to different groups by gavage daily in the following programs: Pregnancy variation (P) to females from 5th to 15th days of pregnancy; Pregnancy and lactation variation (P+L): to females as above and during lactation for 4 weeks; Pregnancy+lactation+post weaning variation (P+L+P) as above plus to the young male rats (F1 generation) up to 8 weeks. Neurotoxicological investigations were conducted on the F1 rats at the age of 12 weeks. Spontaneous electrocorticograms (ECoG) were recorded on the anesthetized rats from the somatosensory, visual and auditory cortex. Cortical evoked potentials (EP) were recorded from the same areas subsequently. Conduction velocity and refractory periods of the tail nerve was investigated. Treatment by Dim, DDVP and MP during P and P+L of the mothers did not influence the bioelectric activity of the offsprings significantly. The same treatment by the P+L+P programme, resulted in significant changes. Frequency of the spontaneous ECoG waves grew significantly in all dose groups of P+L+P group. Latency time become shorter after somatosensory. light or acoustic stimuli respectively on one hand and the beginning of the of answer of these by the evoked potential (EP) waves on the other hand. Conduction velocity of the tail nerve diminished, refractory periods grew dose dependently and significantly at the P+L+P programs with all the three pesticides. Cortical single unit activity was studied after the i.p administration of 1/5 LD50 of the three organophosphates (OP). The decrease of the firing frequencies was observed. The amplitude of the hippocampal population spikes increased. The changes observed in these studies point toward a higher excitation state of the CNS and a disturbed conduction of the nervous impulses of the peripheral nerves. These results could be taken into consideration when deciding on human contaminations by OP-s.

Developmental neurotoxicological effects of lead and dimethoate in animal experiments.

Neurophysiological changes caused by parallel treatment with inorganic lead and dimethoate (a combination of possible health risk at population level) were investigated in different phases of the ontogenesis. Wistar rats were treated by gavage with lead (80.0 or 320.0 mg/kg); with dimethoate (7.0 or 28.0 mg/kg), or with their combination on days 5-15 of pregnancy, days 5-15 of pregnancy + days 2-28 of lactation (females of P generation), or days 5-15 of pregnancy + days 2-28 of lactation (females of P generation) + 8 weeks after weaning (males of F1 generation). Electrophysiological parameters (electrocorticogram, cortical evoked potentials) of the F1 male rats in the above groups were investigated at the age of 12 weeks. Both spontaneous and evoked electrophysiological phenomena showed dose-, treatment- and combination-dependent changes (e.g. significantly decreased mean amplitude and increased frequency of the electrocorticogram, lengthened latency and duration of the somatosensory, visual and auditory evoked potentials) which seemed to be more pronounced in the groups treated with the combination of lead and dimethoate than in the groups given lead or dimethoate alone. The results indicate that a simultaneous, pre- and postnatal exposure to the neurotoxicants, lead and dimethoate, considerably altered the functioning of the central nervous system.

Electrophysiological biomarkers of an organophosphorous pesticide, dichlorvos.

The correlations between the relatively low level, chronic dichlorvos (DDVP) treatment and the early electrophysiological changes were investigated in three series of experiments. In the first series, male Wistar rats were orally given daily by gavage 0.98, 1.96 and 3.92 mg/kg of DDVP for 4, 8, or 12 weeks, and recordings were made at the end of each period. In the second one, the male and female rats of three consecutive generations were treated with the same doses, the investigated parameters were recorded at the age of 12 weeks of the male animals. In the third experiment, the doses were administered in different stages of development: during pregnancy, pregnancy + lactation, pregnancy + lactation + postweaning, and the electrophysiological markers were recorded also at the age of 12 weeks of male offspring. The analyzed elecrophysiological parameters were: electrocorticogram, sensoric cortical evoked potentials, conduction velocity and refractory periods of peripheral nerve. The data showed that the relatively low level dichlorvos exposure caused dose-, duration-, generation-, developmental stage-dependent and partly significant alterations in all the investigated electrophysiological parameters. The analyzed functional parameters proved to be sensitive biomarkers of the exposure as they were changed by the lower doses, while the brain cholinesterase activity was considerably inhibited only in the groups given the highest dose.

Epidemiological investigations and experimental model studies on exposure of pesticides.

Authors carried on epidemiological examinations on plant protection workers to find early symptoms (biomarkers) of moderate contamination by pesticides. Measurement of changes in cholinesterase and gamma glutamyltransferase enzyme activity did not reveal that people were affected. Determination of chromosome abnormalities from peripheral lymphocytes disclosed numerical aberrations at an early stage and lasted after cessation of work for several months. There were differences in the results among different groups of plant protection workers, as well as among those working in open field or in glasshouses. Women, who carried out horticultural work in glasshouses after spraying showed some chromosome abnormalities too. Experimental rats treated chronically with organophosphates exhibited changes in spontaneous and evoked brain electrical activity (ECoG). Concerning the peripheral nervous activity, conduction velocity became slower, absolute and relative refractory periods became longer. These proved sensitive biomarkers too, which could be used in early detection of contamination.

Biological monitoring and health surveillance of a group of greenhouse pesticide sprayers.

Repeated extensive medical examinations were carried out in 11 workers spraying organophosphate (OP), carbamate and pyrethroid pesticides in greenhouses during the whole year and in 10 control persons. On a questionnaire their social, health and family status and their working conditions were recorded. Before and after a regular spraying period with pyrethroids for 3 months the following tests were carried out: urinalysis, haematology, immunoglobulin (Ig) G, IgA and IgM levels, whole blood cholinesterase (ChE) activity, serum gamma-glutamyltransferase (GGT) activity, chromosome analysis and electrocardiography (ECG). Atmospheric concentrations of pyrethroids as well as their concentration in the blood and urine of pesticide workers were determined by means of gas-liquid chromatography (GLC). No abnormalities related to the work were found in the tests.

Behavioral effects of subchronic intoxication with parathion-methyl in male Wistar rats.

The behavioral effects of subchronic exposure of male Wistar rats to the organophosphorus compound parathion-methyl (for 6 weeks 1/50 or 1/100 of LD50, PO) were studied. Open-field (OF) and elevated plus-maze (EPM) tasks were used to decide whether or not the compound can affect behavior. Significant effects were measured in the OF activity during the first minute, on the activity of crossing outer squares, increasing latencies to leave center, start of rearing, grooming, and defecation. EPM parameters showed an increased amount of time spent in the open arms and a clear tendency to enter more frequently open arms. The defecation rate in the EPM was significantly decreased. Results are discussed in terms of effects on emotional behavioral components (arousal) and on physiological functioning of the peripheral nervous system (lengthening of latencies).

Neurophysiological markers as early signs of organophosphate neurotoxicity.

The central and peripheral nervous system effects of acute and subchronic exposure to three organic phosphoro-acid esters (dimethoate, dichlorvos, parathion-methyl) were studied. CNS-dependent variables included mean EEG amplitude, mean frequency of the EEG, and the activity (power density) of six component frequency bands. Peripheral nervous system evaluations included determinations of conduction velocity, and both relative and absolute refractory periods. Cholinesterase activity was measured in blood, brain and other organs. The results indicate that acute large doses of these agents produce substantial changes in these measures of CNS and PNS function. In subchronic experiments it was found that a six weeks administration of 1/50 LD50 of the chemicals induced early functional changes in both the central and the peripheral nervous systems. It is recommended that when cholinesterase inhibition is detected in humans, functional evaluations of CNS and PNS should follow.

A study on behavioral, neurotoxicological, and immunotoxicological effects of subchronic arsenic treatment in rats.

Male Wistar rats were treated for 4, 8, and 12 wk with 3.33, 6.66, 13.3, or 26.6 mg/kg of inorganic arsenic (NaAsO(2)) per os by gavage. Changes in behavioral and electrophysiological parameters (spontaneous open-field exploration; electrocorticogram mean frequency and power spectrum; latency and duration of somatosensory, visual, and auditory evoked potentials; conduction velocity; and relative and absolute refractory period of a peripheral nerve) were determined. Treated rats exhibited hypoactivity of horizontal ambulation in the open field and showed depressed rates of grooming. The electrophysiological data, recorded from anesthetized rats, did not show any significant dose- and time-dependent changes. Changes in humoral immune response, tested after 4 wk of treatment, were not marked. The weight of organs responsible for immune response (thymus, spleen, adrenals), was significantly reduced, as were delayed-type hypersensitivity (DTH) reaction and mean cell volume (MCV) of red blood cells a hematological parameter. Plaque-forming cell (PFC) assay proved to be insensitive in this short-time exposure. These results suggest that subchronic low-level exposure to arsenic can affect immune responses and/or spontaneous behavior of rats.

Life-time exposure to dichlorvos affects behaviour of mature rats.

Wistar rats were exposed to dichlorvos [CAS number 62737]. Doses were 1/25; 1/50; and 1/100 LD50, that is 3.88; 1.94; 1.46; and 0.97 mg kg-1 DDVP, respectively, throughout gestation (GD1-birth) and during suckling via oral dosing to the dams, and then via the same doses by gavage for the rest of their lives. The offspring were tested in an open field (OF), a multiple T-maze, and in a 'novelty-induced-grooming' test to assess behavioural competence as adults. Dose-related increases in running time and incorrect choices in the maze were observed during the first 2 weeks of a 3-week study at 9-11 weeks of age. Horizontal activity was increased, vertical activity decreased, and defecation decreased in the OF at 9-12 weeks of age; these changes were again dose-related. Sleep was also affected at 12 weeks of age. AChE activity in the brain and in blood at sacrifice was roughly 40% to 65% of control, again reflecting the doses administered. The significantly changed behavioural profile of DDVP treated rats may serve as a useful biomarker to judge functional damage of CNS properties.

Behavioural and functional neurotoxicological changes caused by cadmium in a three-generational study in rats.

1. Three consecutive generations of Wistar rats were orally treated by gavage with 3.5, 7.0 or 14.0 mg/kg cadmium (in form of cadmium chloride diluted in distilled water) over the period of pregnancy, lactation and 8 weeks after weaning. 2. Behavioural (open field behaviour) and electrophysiological (spontaneous and evoked cortical activity, etc.) parameters of male rats from each generation were investigated at the age of 12 weeks. 3. The main behavioural outcomes were change in vertical exploration activity (rearing) and increased exploration of an open field centre. The spontaneous and evoked electrophysiological variables showed dose- and generation-dependent changes (increased frequencies in the electrocorticogram, lengthened latency and duration of evoked potentials, etc.) signalling a change in neural functions. 4. The data show that low-level, multigeneration exposure to inorganic cadmium can affect functions of the nervous system. This suggests that cadmium exposed human populations may be at risk of developing nervous system disorders.

Behavioural effects of subchronic lead treatment in combination with ethanol in rats.

The effect of lead acetate administration during perinatal (1. prenatal, 2. prenatal and suckling period, 3. prenatal + suckling period + 4 weeks after weaning) development in combination with ethanol was investigated in Wistar rats at the age of 12 weeks on open-field behaviour and auditory startle response. Lead intoxication has on the investigated behavioural parameters the most pronouncing effect when applied during the days 5-15 of pregnancy.