Suicídio por autointoxicação entre adolescentes e adultos jovens brasileiros: estudo de séries temporais / Suicidio por autointoxicación entre adolescentes y adultos jóvenes brasileños: estudio de las series temporales / Suicide by self-poisoning among brazilian adolescents and young adults: time-series study

RESUMO Objetivo: analisar a tendência temporal da mortalidade por autointoxicação entre adolescentes e adultos jovens brasileiros no período de 2000 a 2017. Método: estudo de séries temporais da mortalidade por suicídio por autointoxicações (X60 a X69) entre adolescentes e jovens adultos, entre os anos de 2000 a 2017. Calcularam-se os coeficientes de mortalidade por 100.000 habitantes e mortalidade proporcional. Optou-se pela regressão linear de Prais-Winster para análise de tendência. Resultados: percebeu-se uma linearidade na tendência da mortalidade geral por suicídio nessa população. Evidenciou-se uma tendência decrescente entre os indivíduos do sexo feminino, das faixas etárias de 15 a 19 anos e 20 a 24 anos, das regiões Nordeste e Centro-Oeste e que adotaram métodos de suicídio por pesticidas e produtos químicos ou substâncias nocivas não especificadas. Destacou-se também uma tendência crescente da mortalidade pelo uso de todas as classes medicamentosas analisadas, solventes orgânicos e outros inalantes. Conclusão: este estudo identificou um aumento considerável na utilização de medicamentos e inalantes como método para o suicídio entre adolescentes e adultos jovens.

RESUMEN Objetivo: analizar la tendencia temporal de la mortalidad por autointoxicación entre adolescentes y adultos jóvenes brasileños en el período de 2000 a 2017. Método: estudio de las series temporales de la mortalidad por suicidio por autointoxicaciones (X60 a X69) entre adolescentes y jóvenes adultos, entre los años de 2000 a 2017. Se calcularon las tasas de mortalidad por 100.000 habitantes y mortalidad proporcional. Se optó por la regresión lineal de Prais-Winster para análisis de tendencia. Resultados: se percibió una linealidad en la tendencia de la mortalidad general por suicidio enesta población. Se evidenció una tendencia decreciente entre los individuos del sexo femenino, de las franjas de edad de 15 a 19 años y 20 a 24 años, de las regiones Nordeste y Centro-Oeste y que adoptaron métodos de suicidio por plaguicidas y productos químicos o sustancias nocivas no especificadas. Se destacó también una tendencia creciente de la mortalidad por el uso de todas las clases de medicamentos analizadas, solventes orgánicos y otros inhalantes. Conclusión: este estudio identificó un aumento considerable en la utilización de medicamentos einhalantes como método para el suicidio entre adolescentes y adultos jóvenes.

ABSTRACT Objective: to analyze the temporal trend of mortality from self-intoxication among adolescents and young adults in Brazil from 2000 to 2017. Method: time-series study of mortality from suicide from self-intoxication (X60 to X69) among adolescents and young adults, between 2000 to 2017. The coefficients of mortality per 100,000 population and proportional mortality were calculated. The Prais-Winster linear regression was chosen for trend analysis. Results: there was linearity in the trend of overall suicide mortality in this population. A decreasing trend was evidenced among female individuals, aged 15 to 19 years old and 20 to 24 years old, from the Northeast and Midwest regions and who adopted suicide methods by pesticides and chemical products or unspecified harmful substances. A growing trend of mortality due to the use of all drug classes analyzed, organic solvents, and other inhalants were also highlighted. Conclusion: This study identified a considerable increase in the use of medications and inhalants as a method of suicide among adolescents and young adults.

Actualización en abuso de drogas por vía nasal / Update on drug abuse by nasal route

La vía nasal, ya sea mediante la inhalación o aspiración, se ha convertido en una ruta atractiva para quienes abusan de sustancias, principalmente por la fácil accesibilidad y la rápida absorción sistémica, además de evitar las consecuencias asociadas al uso de drogas intravenosas (enfermedades de transmisión). El objetivo de esta revisión es presentar una actualización de diversas sustancias que son utilizadas por esta vía, enfocándose en aquellas en las que se ha documentado daños en la anatomía nasal.

The nasal route, either by inhalation or aspiration, has become an attractive route for substances abusers, mainly because of its easy accessibility, rapid systemic absorption and also to avoid the consequences associated with intravenous drug use (transmitted diseases). The objective of this review is to present an update of various substances that are used by this route, focusing on those in which damage to the nasal anatomy has been documented.

Death Related to Nitrous Oxide Abuse: Two Cases Report / 대한법의학회지

Nitrous oxide is medically used as an anesthetic gas and as an additive in whipped cream production. Few cases of death from nitrous oxide intoxication have been reported in Korea. However, fatalities due to inhalation of pure nitrous oxide in an amount enough to cause death have been recently increasing. We report two cases of death related to nitrous oxide abuse with a review of literature focusing on the fact that nitrous oxide abuse can be considered as a possible cause of death if appliances with nitrous oxide contents were found during the investigation, and the autopsy and toxicological findings cannot be attributed to nitrous oxide intoxication.

The prevalence of inhalant use and associated factors among adolescents in Belo Horizonte, Brazil / Prevalência do uso de inalantes e fatores associados em adolescentes de Belo Horizonte, Brasil

The scope of this study was to establish the prevalence of inhalant use among adolescents and its association with marijuana use, alcohol consumption, socioeconomic status and gender. A cross-sectional study was performed with a representative sample of 891 adolescents from public and private schools in the city of Belo Horizonte, Brazil. Data were collected using two self-administered questionnaires: the Alcohol, Smoking and Substance Involvement Screening Test (ASSIST) and the Alcohol Use Disorders Identification Test (AUDIT C). The socioeconomic status was evaluated using the Social Vulnerability Index, mother's education level and type of school (public or private). The data were analyzed using the chi-square test (p < 0.05) and logistic regression analysis. The prevalence of inhalant use was 7.9%. No significant association was found between the use of inhalants and socioeconomic status after the logistic regression analysis. Inhalant use among adolescents was associated with marijuana use (OR: 4.61; 95% CI: 2.27 - 9.36) and with binge drinking (OR: 5.02; 95% CI: 2.57 - 9.81).

O objetivo deste estudo foi avaliar a prevalência do uso de inalantes em adolescentes e sua associação com o uso de maconha, consumo de álcool, condição socioeconômica e gênero. Um estudo transversal foi realizado em uma amostra representativa de 891 adolescentes de escolas públicas e privadas de Belo Horizonte, Brasil. Os dados foram coletados por meio de dois questionários autoaplicáveis: o Alcohol, Smoking and Substance Involvement Screening Test (ASSIST) e o Alcohol Use Disorders Identification Test (AUDIT C). O Índice de Vulnerabilidade Social, o nível de escolaridade da mãe e o tipo de escola (pública ou privada) foram utilizados para determinar o nível socioeconômico. Os dados foram analisados utilizando o teste qui-quadrado (p < 0.05) e a análise de regressão logística. A prevalência do uso de inalantes foi de 7,9%. Não houve associação entre o uso de inalantes e o nível socioeconômico após a análise de regressão logística. O uso de inalantes por adolescentes esteve associado ao uso de maconha (OR: 4.61; 95% CI: 2.27 - 9.36) e ao consumo abusivo de álcool (OR: 5.02; 95% CI: 2.57 - 9.81).

Encuesta nacional sobre uso, abuso y prevalencia del consumo de drogas del nivel medio de educación / National survey on the use, abuse and prevalence of drug use at the intermediate level of education

Guatemala cuenta con una población de 15.073,375 personas, con pirámide poblacional mayoritariamente joven. Este estudio de tipo transversal, descriptivo, correlacional en una muestra de 13,856 estudiantes de ambos sexos, en edades comprendidas entre los 11 y 22 años de edad, del nivel medio y diversificado de educación pública y privada a nivel nacional, analiza el problema de drogas en esa población. La información se obtuvo a través del instrumento SIDUC, proporcionado por la CICAD de la OEA. El estudio evidenció las drogas legales, alcohol y tabaco, con altas prevalencias de consumo y las drogas ilegales identificadas como de mayor consumo fueron, citadas en orden decreciente, la marihuana, los inhalables y la cocaína. Se detectó que la autopercepción de riesgo y la familia funcional, son factores que reducen en cierto grado la experimentación y el consumo de drogas. El ambiente docente de la educación formal y el grado de involucración parental en las actividades de las y los estudiantes, así como la influencia del grupo, son factores que según el caso, pueden ser de protección o riesgo para el consumo de drogas. Se encontraron indicios de la disponibilidad de drogas tanto dentro, como en los alrededores de las instituciones educativas, así como de necesidad de tratamiento por consumo de drogas, elementos todos que ameritan investigarse a futuro. Se recomienda propiciar la investigación y vigilancia epidemiológica en ésta y otras poblaciones, para profundizar en la caracterización del problema adictivo, para orientar con información nacional los esfuerzos preventivos en el país.(AU)

Anxiety symptoms in crack cocaine and inhalant users admitted to a psychiatric hospital in southern Brazil / Sintomas de ansiedade em usuários de crack e inalantes admitidos em uma unidade psiquiátrica na Região Sul do Brasil

OBJECTIVE: The occurrence of psychiatric comorbidity among individuals with crack or inhalant dependence is frequently observed. The objective of this study was to investigate anxiety symptoms among crack cocaine and inhalant users in southern Brazil. METHODS: The study investigated two groups of volunteers of equal size (n = 50): one group consisted of crack cocaine users, and the other group consisted of inhalant users. Research volunteers completed the Portuguese versions of the State-Trait Anxiety Inventory (STAI), Hamilton Anxiety Rating Scale (HAM-A), and Self-Report Questionnaire (SRQ). RESULTS: Both crack and inhalant users experience significant symptoms of anxiety. Inhalant users presented significantly more anxiety symptoms than crack users according to the HAM-A questionnaire only. In contrast to the results of the HAM-A, the STAI failed to demonstrate a significant difference between the two groups of substance users. SRQ scores revealed that crack and inhalants users had significant degrees of morbidity. CONCLUSION: A significant difference regarding anxiety symptomatology, especially state anxiety, was observed among inhalant and crack users. Anxiety and overall mental psychopathology were significantly correlated in this sample. The results indicate that screening initiatives to detect anxiety and additional psychiatric comorbidities among crack and inhalant users are feasible and relevant.

OBJETIVO: Investigar sintomas de ansiedade em usuários de crack e inalantes no Sul do Brasil. MÉTODOS: Oestudo investigou dois grupos de voluntárioscomomesmonúmero de indivíduos (n = 50): um grupo consistiu de usuários de crack e o outro grupo, de usuários de inalantes. Os voluntários da pesquisa completaram as versões em português das escalas de ansiedade State-Trais Anxiety Inventory (STAI) e Hamilton Anxiety Rating Scale (HAM-A), e o Questionário de Autoavaliação (SRQ). RESULTADOS: Ambos os grupos apresentaram sintomas significativos de ansiedade. Os usuários de inalantes apresentaram escores quanto a HAM-A significativamente superiores aos usuários de crack. Ansiedade e psicopatologia geral se apresentaram significativamente correlacionados. CONCLUSÃO: Sintomas de ansiedade são frequentes entre usuários de crack e inalantes. Um processo de triagem de sintomas de ansiedade entre usuários de crack e inalantes deve facilitar ainda mais as intervenções terapêuticas nesta área.

Factors on the Suicidal Attempt by Gender of Middle and High School Student

PURPOSE: The suicide rate of adolescents in Korea is increasing annually. Therefore, this research was done to identify the suicide attempt rate of middle and high school students and to identify factors that influence suicidal attempts. METHODS: The Korea Youth Health Risk Behavior Web-based Survey (2007) was used as data. Discriminant analysis and logistic regression were performed to analyze the data depending on gender to consider the gender difference in assessing the influence of each independent variable on suicidal attempts. RESULTS: Discriminant analysis according on gender showed that 13 factors correlated with suicidal attempts for boys, and 20 factors for girls. The most highly correlated factors were smoking, depression and inhalation experience. For inhalation experience, boys had 2.7 times higher possibility of suicide attempts (95% CI 1.8-3.0) and girls, a 2.4 times higher possibility (95% CI 1.7-3.5). CONCLUSION: The results of the study indicate a need to classify adolescents for expectation of suicide risk and high danger for suicidal attempts through, and introduce suicide prevention programs for these adolescents. In particular, it is necessary to start intervention with students who smoke, have sexual and inhalation experiences and high levels of depression.

Occupational Diseases in Workers Exposed to Organic Solvents / 한양의대학술지

Organic solvents are hydrocarbon-based substances that dissolve another substance. Organic solvents are usually lipid soluble, volatile and commonly used for painting, printing, degreasing, cleaning, thinning and extraction. Due to their volatility and lipid solubility, organic solvents are easily absorbed across the alveolar-capillary membrane and through the skin. Because organic solvents are lipophilic, they tend to be distributed to lipid-rich tissue, such as adipose tissue, nervous system and liver. Almost all organic solvent can induce skin diseases such as acute irritant dermatitis and chronic eczema. Some organic solvents are associated with allergic contact dermatitis. General and nonspecific central nervous system depression is another common toxic effect induced by most organic solvents. It shows symptoms which are the same as those from alcohol drinking, and those symptoms are completely resolved by removal from exposure to solvents. Long term and repeated exposures to organic solvents can also lead to chronic adverse neurobehavioral effects. These effects are also called as chronic toxic encephalopathy, chronic solvent intoxication and psycho-organic syndrome, and commonly reported symptoms of them are headache, depression, anxiety, and impairment of recent memory. Organic brain lesions can be found in workers suffering from psycho-organic syndrome, and in this case, there is a possibility of persistent disabilities. Carbon disulfide, n-hexane, and methyl n-butyl ketone are specifically toxic to the peripheral nervous system, and cause a symmetric ascending sensory and motor polyneuropathy. Halogenated hydrocarbons including carbon tetrachloride show toxic effects on the heart, liver, kidney, and blood. Toluene can sensitize the heart to arrhythmogenic effects of epinephrine, so sudden death in young and healthy people can be ensued from glue sniffing. Benzene is able to induce any type of leukemia, especially in victims with benzene-associated aplastic anemia. Exposure to some solvents during pregnancy has potential to induce congenital malformation and spontaneous abortion. In the treatment of diseases by organic solvents, the first step should be removal from exposure to the causative solvent.

Morphological Study of Respiratory Portion of Mouse Lung following Chemical Glue-Vapor Inhalation / 대한해부학회지

Industrial glues contain many kinds of organic solvents and glue sniffing by young people has become a social problem in Korea. Glue vapor may induce chronic toxicities different from those induced by exposures to the solvent of single component. We studied the effects of the inhalation of glue vapor on the primary target organ, the pulmonary epithelium of the respiratory system. Vapor samples of glue were collected for analysis; the components were acetone, n-hexane, methyl cyclopentane, c-hexane, and toluene. For the inhalation of glue vapor, experimental mice were exposed in a whole body chamber for 20 min/d for 3, 5, 7, and 14 d. Control groups were exposed to room air. Animals were euthanized and lung tissues were fixed in 10% neutral formalin for light microscopy, and in 2.5% glutaraldehyde plus 1.5% paraformaldehyde for electron microscopy. The results are as follows. 1. Alcianophilic bands were not detected in the normal alveolar epithelium, but weak alcianophilic bands were detected in bronchioles. Alcian blue-PAS and PAS positive cells were found in the mucosae of mice exposed to glue vapor for 5 and 7 d. 2. Types I and II pneumocytes and capillary endothelial cells were found in the normal alveolar epithelium. The blood-air barrier consists of Type I pneumocytes, a common basal lamina, and the capillary endothelium. 3. The alveolar epithelium of vapor-exposed mice showed more type II pneumocytes. In the longerexposed group, Type I pneumocytes and endothelial cells contained many pinocytotic vesicles. 4. The vapor-exposed lungs showed macrophages in the alveolar space, mild interstitial swelling, and increased numbers of collagenous fibers. Clearly, ultrastructural changes in pulmonary epithelia can occur following glue sniffing.

Glue Sniffing Presenting with Severe Hypokalemia and Metabolic Acidosis: A Case Report

Toluene is an aromatic hydrocarbon found in glues, cements, and solvents. Chronic or acute exposure is known to cause acid-base and electrolyte disorders and to be toxic to both the nervous system and the hematopoietic system. The three major clinical presentations involve neuropsychiatric, gastrointestinal, and muscular disorders, whereas toluene intoxication is difficult to diagnose without a history of substance abuse, such as glue sniffing. We report the case of a 27-year-old women who presented with the three major clinical manifestations associated with profound hypokalemia (K+=1 mEq/L) and metabolic acidosis (pH=7.17) after prolonged glue sniffing. To make an early diagnosis, the emergency physician should consider toluene intoxication in patients presenting with altered mental status, hypokalemic muscular paralysis, and a history of glue sniffing.

Morphological Changes of the Olfactory Mucosa in Mice Exposed to Industrial Bond Vapor / 대한이비인후과학회지

BACKGROUND AND OBJECTIVES: Recently, accidents have been reported of young adults who inhale industrial bond vapor. Acquiring industrial bond is easy for young adults, and glue sniffing has thus become a serious social problem. However, there have been few reports concerning the changes in the olfactory epithelium after exposure of industrial bond vapor. The aim of this study is to describe the morphological changes of the olfactory mucosa after being exposed to industrial bond vapor, using HE, AB, AB-PAS stains, immunohistochemistry and the electron microscopy. MATERIALS AND METHOD: Healthy ICR mice were exposed to industrial bond vapor (acetone 5212+/-1268 ppm, c-hexane 3757+/-711 ppm, methylcyclopentane 1820+/-375 ppm, n-hexane 139+/-30 ppm and toluene 0.9+/-1.4 ppm). The vapor was given to each animal with duration of 20 min/day for 3 days, 5 days, 7 days or 14 days in a specially designed box for this study. After exposure to industrial bond vapor, mice olfactory mucosae were excised and prepared for HE, AB, AB-PAS stains, immunohistochemistry and electron microscopy. RESULTS: Loss of cells and disarrangements of olfactory epithelium were prominent on the third day of exposure and the epithelium recovered to the normal state after the day 7 in the HE stain. And there were also definite ultrastructural changes in the epithelium : loss of microvilli in supporting cells, exposure of olfactory vesicles to the luminal surface and apoptotic bodies in electron microscopic study. Study with the AB and AB-PAS stains demonstrated an evidence of decreased mucin secretion on the day 3 and the content of mucin was normalized after the day 7. In the PCNA study, cells were unable to proliferate until day 3. The proliferation potential were increased (4 fold) on day 5 and returned to normal on day 14. CONCLUSION: This result indicated that industrial bond vapor can damage the olfactory epithelium of mice which can recover rapidly. Apoptosis and active proliferation could be the factors that are involved in the recovery of the epithelium that is open to regular industrial bond vapor exposure on daily basis.

A Case of Diffuse Cortical Necrosis after Glue Sniffing / 대한신장학회잡지

The renal cortical necrosis occurs in approximately 2% of adult patients with acute renal failure. The causes of renal cortical necrosis were usually associated with obstetrical problems. However, the distinctive changes occurred over the past 15 years in the etiology with a high incidence of non-obstetric causes than obstetric ones. We experienced a rare case of diffuse bilateral renal cortical necrosis in 16-year-old man who had a history of glue sniffing. To our knowledge, this is the first report in our country. A 16-year-old man was admitted with vague flank pain and oliguria. There was history of frequent adhesive glue sniffing. Laboratory data were as follows : BUN 77mg/dL, creatinine, 9.3mg/dL, protein 3+, RBC many/HPF, WBC 1-4/HPF in urinalysis, HBsAg(-), Anti-HBs(+), C(3)10.5mg/dL, C(4)7.4mg/dL), IgG 1,865mg/mL, IgA 512mg/mL. The kindey size was normal in ultrasonography. Renal cortex was diffusely not enhanced in MIJ Tl weighted image. Diffuse bilateral renal cortical necrosis was diagnosed by renal biopsy. In this case, adhesive glue sniffing may be a cause of acute cortieal necrosis.

A case of aplastic anemia after habitual sniffing of glue and volatile substances / 대한내과학회지

The inhalation of volatile substances has becoming a popular fad among adolescents in the world. Glue sniffing is associated with injury of nervous system, liver and kidney. And rarely abnormality of blood and bone marrow suppression can develop. The main components of volatile substances that cause hematologic abnormality is thought to be benzene, toluene, and xylene. A 24 year-old male was admitted to our hospital due to gum bleeding. He was a chronic glue and organic solvents sniffer for 6 years, and quit sniffing 1 year before admission. He had no specific drug history. On admission, CBC was as follows: WBC 2,500/mm3; hemoglobin 8.9g/dl; hematocrit 25.1%; platelet 2,000/mm3. Bone marrow biopsy showed severe hypocellular marrow compatible with aplastic anemia. We report a case of aplastic anemia after habitual sniffing of glue and volatile substances with brief review of the literature.

A Case of Distal Renal Tubular Acidosis Detected after Glue Sniffing / 대한신장학회잡지

We describe a case of distal renal tubular acidosis in a 20-year-old woman with a history of glue sniffing. On admission she complained of nausea and somnolence. Severe hypokalemia and hyperchloremic metabolic acidosis with normal anion gap were noted. Her urinary osmolar gap and anion gap results were consistent with presence of renal tubular acidosis. Bicarbonate loading test along with urine PCO2 confirmed that she had type 1 renal tubular acidosis due to hydrogen ion secretion defect. Immunohistochemical staining of renal biopsy specimen with anti H+-ATPase antibody showed absence of proton pump in the collecting duct. Thus a case of distal renal tubular acidosis in association with glue sniffing is reported with a review of literatures.

The general characteristics and states of family of chemical-abusers in an adolescent jail

BACKGROUND: The drug abuse has become one of social problems especially in the adolescents. It has been well known that the drug abuse is concerned with interaction of biopsychosocial factors and farnily relation factors. So I have studied the general characteristics and rearing attitude and family state of the adolesents who were in a jail because of drug abuse and have intended to give some help for establishing effective strategies for family education and therapy. METHODS: The study was done for adolescents who were in a jail because of violation the illegal drug control law. The group was total 55 men and the age distribution was frorn 15 to 20 years. The Questionnaire was used in Mar 1996 for study and I analyzed 53 cases excluding 2 cases because they were nearly illiterate. The FACES III(Family Adaptability and Cohesion Evaluation Scales), family APGAR score and PBI(Parental Bonding Instrument) were used for evaluating the characteristics of family function and the parental rearing attitude. Statistical management with SAS was executed for data analysis. RESULTS: The average age of the group was 6.9+/-1.4. 48.1% of them lived in the metropolitan area, 40.4% lived in the middle-sized cities and 11.5% lived in the small country towns. The education level of 91.8% was under middle-school graduate. They have use drugs since the age of 14.6+/-1.8, they began to use glue sniffing at the first time in 78.8% and butane gas inhalation in 17.3%. The state of family showed the death of father in 28.9% and the death of mother in 13.5 % and 76.9% of deaths occured before they have become 13 years. Their parents divorced in 25 %. The mean APGAR score was 4.56+/-2.6, which means moderately dysfunctional state of family. In FACES III adaptability score was 20.3+/-5.7 and cohesion score was 26.2+/-6.9. According to the family type by FACES III, there were 5 cases(9.4%) in balanced, 19 cases(35.9%) in midrange, and 29 cases(54.7%) in extreme. In PBI mother overprotection score was 16.24+/-4.59, mother care score was 22.5+6.8, father overprotection score was 16.71+/-5.1 father care was 21.94+/-6.24. CONCLUSIONS: The drug abused adolescents in a jail were in hadicapped family because of deaths and divorce of parents. Their family function score was low and more than half of them had the extreme type of family. Therefore it is wise for us to have a concern for the family problem when understanding and managing drug abused adolescents.

Effects Of Glue Sniffing On Weight Increase Or Central Nervous System Of Young Rat / 예방의학회지

Industrial glues, known as 'Bonds' in Korea, contain many kinds of organic solvents, and glue sniffing of youths became one of the social problems in Korea. Mixed exposures to solvents by glue sniffing may induce chronic toxicities different from those by exposures to solvents of single component. To test effects of the glue sniffing on weight gain or central nervous system, two groups of 20 male Sprague-Dawley rats were exposed to air(control group) or vapors of the glues to narcotic status(exposed group), and weight check, tail flick test, hot plate test, rotarod treadmill test were done on the 14th, 24th, 36th, 45th, 53rd, 86th, 102nd, 117th, 134th and 151st days after the first exposure. On the 188th day, their brains were excised and examined by a pathologist. Weight gain, controlled against time change, showed significant difference between the groups, but response times in tail flick test, hot plate tests, and rotarod treadmill test didn't. In pathological examination with blind method, no macroscopic or microscopic difference were found between the two groups. These results suggests that organic lesion in central nervous system may not ensue glue sniffing, but, before firm conclusion, more studies in various exposure conditions should be followed.