Correlation analysis and benchmark dose study on bone metabolic biochemical index of low doses of exposed hydrogen fluoride workers / 中华劳动卫生职业病杂志

Objective: To analyze correlation of occupational hydrogen fluoride exposure to low doses of bone metabolism index through occupational epidemiological investigation and benchmark dose calculation. Methods: In May 2021, using cluster sampling method, 237 workers exposed to hydrogen fluoride in a company were selected as the contact group, and 83 workers not exposed to hydrogen fluoride in an electronics production company were selected as the control group. The external exposure dose and urinary fluoride concentration, blood and urine biochemical indicators of the workers was measured.The relationship between external dose and internal dose of hydrogen fluoride was analyzed. The external dose, urinary fluoride was used as exposure biomarkers, while serum osteocalcin (BGP), serum alkaline phosphatase (AKP) and urinary hydroxyproline (HYP) were used as effect biomarkers for bone metabolism of hydrogen fluoride exposure. The benchmark dose calculation software (BMDS1.3.2) was used to calculate benchmark dose (BMD) . Results: Urine fluoride concentration in the contact group was correlated with creatinine-adjusted urine fluoride concentration (r=0.69, P=0.001). There was no significant correlation between the external dose of hydrogen fluoride and urine fluoride in the contact group (r=0.03, P=0.132). The concentrations of urine fluoride in the contact group and the control group were (0.81±0.61) and (0.45±0.14) mg/L, respectively, and the difference between the two groups was statistically significant (t=5.01, P=0.025). Using BGP, AKP and HYP as effect indexes, the urinary BMDL-05 values were 1.28, 1.47 and 1.08 mg/L, respectively. Conclusion: Urinary fluoride can sensitively reflect the changes in the effect indexes of biochemical indexes of bone metabolism. BGP and HYP can be used as early sensitive effect indexes of occupational hydrogen fluoride exposure.

Effects of 0.01％ and 0.02 ％ atropine eye drops on pupil diameter and accommodation amplitude in myopic children: one-year randomized, double blind, controlled trail / 中华实验眼科杂志

Objective To evaluate the effects of 0.0％ and 0.02％ atropine on pupil diameter (PD) and accommodation amplitude (AMP) in myopic children and analyze its relation factors.Methods A prospective randomized controlled trial design was adopted.One hundred and ninety-three myopia children were included from June to October,2016 in the First Affiliated Hospital of Zhengzhou University,all the children completed one-year follow-up.All the children were divided into three groups randomly,with 72,74 and 80 myopic children in 0.01％ atropine group,0.02％ atropine group and control group,respectively.The myopic children in 0.01％ atropine group and 0.02％ atropine group wore single-vision spectacle lenses and were treated with 0.01％ and 0.02％ atropine eye drops nightly,respectively.The myopic children in the control group wore spectacle lenses only.The PD and AMP were measured at baseline,and 4,8 and 12 months after treatment.Results There were no significant difference of baselinePD and AMP among the three groups (F=9.321,P=0.820;F=13.209,P=0.220).Compared with basline,after 12 months,the PD increased by 0.75,0.84 and 0.02 mm in 0.01％ atropine group,0.02％ atropine group and control group,respectively.There were statistically significant differences of PD among three groups at different time points (Fgroup =2.168,P=0.013;Ftime =2.139,P=0.015;Finteraction =2.148,P=0.001).Compared with baseline,the PD of 0.01％ atropine group and 0.02％ atropine group were increased 4,8 and 12 months after treatment,and the difference was statistically significant (all at P＜0.001).The PD was stable in control group.After 12 months,the AMP were reduced by 1.25,1.12 and 0.28 D in 0.01％ atropine group,0.02％ atropine group and control group,respectively.There were statistically significant differences of AMP among the three groups at the different time points (Fgroup =18.346,P =0.034;Ftime =1.823,P =0.002;Fintercation =3.239,P =0.023).Compared with baseline,the AMP of 0.01％ atropine group and 0.02％ atropine group were increased 4,8 and 12 months after treatment,and the differences were statistically significant (all at P＜0.05).The AMP remained stable in control group.The change of PD in 0.01％ atropine group and 0.02％ atropine group was correlated with age,baseline PD and baseline eye axis length,respectively (β =0.060,P =0.019;β =-0.440,P＜0.001;β =-0.37,P =0.045).The change in AMP of the atropine group was significantly correlated with the baseline adjustment range (β =-0.71,P＜0.001).Conclusions 0.01％ and 0.02％ atropine show similar effects on pupil diameter and accommodation amplitude after 12 months of treatment in myopic children.

Uso de bajas dosis de oxitocina para el manejo de contracción uterina en el transoperatorio de pacientes sometidas a cesárea en el centro obstétrico del Hospital Carlos Andrade Marín / Oxytocin low-dosage use for handling uterine contraction in the transoperative of C-section patients of the Carlos Andrade Marin Hospital Obstetric Center

Introducción: la oxitocina es la droga de elección para el manejo de contracción uterina, sin embargo sus efectos adversos son minimizados. Este estudio pretende determinar la frecuencia de efectos adversos de oxitocina a dosis altas con relación a dosis bajas en el centro obstétrico del Hospital Carlos Andrade Marín. Materiales y métodos: es un estudio observacional descriptivo, en el que se estudió a 52 pacientes que fueron sometidas a cesárea iterativa en el período mayo ­ junio de 2012. Resultados: con el uso de dosis altas de oxitocina se presenta efectos adversos como dolor precordial (p menor 0.05), hipotensión (p 0.002), náusea (p 0.002). Con tres unidades de oxitocina el sangrado no se modifcó. Por otro lado, la satisfacción del cirujano es del 88,5%, similar a los valores reportados a nivel internacional. Conclusiones: con el uso de dosis bajas de oxitocina para el manejo de la contracción uterina en cesárea no hubo aumento del sangrado (promedio 463 ml), por lo que se puede considerar una terapéutica segura para la paciente.

Introduction: Oxytocin is the drug of choice for uterine contraction management, but its side effects are minimized. This study pretends to determine the frequency of side effects of high- dose oxytocin compared to low doses in the Obstetric Center of the Carlos Andrade Marin Hospital. Materials and methods: this is a descriptive study where 52 patients were studies and which were subjected to iterative caesarean study during the period may - june 2012. Results: high doses of oxytocin produce side effects such as chest pain (p less than 0.05), hypotension (p 0.002) and nausea (p 0.002). Three units of oxytocin do not modify the bleeding. Furthermore, surgeon satisfaction is 88.5%, similar to values reported worldwide. Conclusions: the use of low dosage of oxytocin for the management of uterine contractions during a cesarean section, showed no increase in bleeding (average of 463 ml), for which this dose may be considered a safe therapeutic dosage for the patient.

Response of EDAG knockout mice to low-dose radiation-induced damage / 军事医学

Objective To generate the erythroid differentiation associated gene(EDAG) knockout mice and analyze their sensitivity to low dose radiation-induced damage.Methods Zinc finger nuclease technology ( ZFNs ) was used to produce the EDAG knockout mice.The low dose radiation-induced damage was evaluated by peripheral blood cell counts, DNA damage and colony formation of bone marrow cells.Wild-type and EDAG knockout mice were irradiated with 0.31 Gy/min X-ray, one minute per day for seven consecutive days, and the cumulative radiation dose was 2.17 Gy(n=7).The blood cell counts were measured by an automated hemocytometer.DNA damage was detected by immunofluorescence assay with a DNA damage marker p-H2A.x antibody (n=3).The colony formation ability of bone marrow cells was evaluated with a semi-solid culture medium(n=3).Results A model of EDAG knockout mice was established.Compared to wide type mice, white blood cell counts of EDAG knockout mice decreased significantly while the DNA damage marker p-H2A.x expression was increased on the third day after X-ray irradiation.The ability of colony-forming was reduced after 7 days of X-ray irradiation.Conclusion Our present study found that EDAG knockout mice are more sensitive to low dose radiation-induced damage as shown by decreased peripheral blood cells counts, reduced colony-forming ability of bone marrow cells, and increased DNA damage.These results suggest that EDAG knockout mice can serve as a powerful tool for evaluation of the biological effects of low-dose radiation damage.

Sympathetic activity of S-(+)-ketamine low doses in the epidural space / Atividade simpática de cetamina S-(+) em doses baixas no espaço epidural / Actividad simpática de la ketamina S(+)-en dosis bajas en el espacio epidural

BACKGROUND AND OBJECTIVES: S-(+)-ketamine is an intravenous anaesthetic and sympathomimetic with properties of local anaesthetic. It has an effect of an analgetic and local anaesthetic when administered epidurally, but there are no data whether low doses of S-(+)-ketamine have sympathomimetic effects. The aim of this study was to determine whether low doses of S-(+)-ketamine, given epidurally together with local anaesthetic, have any effect on sympathetic nervous system, both systemic and below the level of anaesthetic block. METHODS: The study was conducted on two groups of patients to whom epidural anaesthesia was administered to. Local anaesthesia (0.5% bupivacaine) was given to one group (control group) while local anaesthesia and S-(+)-ketamine were given to other group. Age, height, weight, systolic, diastolic and mean arterial blood pressure were measured. Non-competitive enzyme immunochemistry method (Cat Combi ELISA) was used to determine the concentrations of catecholamines (adrenaline and noradrenaline). Immunoenzymometric determination with luminescent substrate on a machine called Vitros Eci was used to determine the concentration of cortisol. Pulse transit time was measured using photoplethysmography. Mann-Whitney U-test, Wilcoxon test and Friedman ANOVA were the statistical tests. Blood pressure, pulse, adrenaline, noradrenaline and cortisol concentrations were measured in order to estimate systemic sympathetic effects. RESULTS: 40 patients in the control group were given 0.5% bupivacaine and 40 patients in the test group were given 0.5% bupivacaine with S-(+)-ketamine. Value p < 0.05 has been taken as a limit of statistical significance. CONCLUSIONS: Low dose of S-(+)-ketamine administered epidurally had no sympathomimetic effects; it did not change blood pressure, pulse, serum hormones or pulse transit time. Low dose of S-(+)-ketamine administered epidurally did not deepen sympathetic block. Adding 25 ...

JUSTIFICATIVA E OBJETIVOS: cetamina S-(+) é um anestésico intravenoso e simpaticomimético com propriedades de anestésico local. Tem efeito analgésico e de anestésico local quando administrada por via epidural, mas não há dados que relatem se cetamina S-(+) em doses baixas tem efeitos simpaticomiméticos. O objetivo deste estudo foi determinar se cetamina S-(+) em doses baixas, administrada por via epidural em combinação com anestésico local, tem algum efeito sobre o sistema nervoso simpático, tanto sistêmico quanto abaixo do nível do bloqueio anestésico. MÉTODOS: o estudo foi conduzido com dois grupos de pacientes submetidos à anestesia epidural. Anestesia local (bupivacaína a 0,5) foi administrada a um grupo (controle), enquanto anestesia local em combinação com cetamina S-(+) foi administrada ao outro grupo (teste). Idade, altura, peso, pressão arterial sistólica e diastólica e pressão arterial média foram medidos. O método imunoquímico de inibição enzimática não competitiva (Cat Combi Elisa) foi usado para determinar as concentrações de catecolaminas (adrenalina e noradrenalina). O ensaio imunoenzimométrico com substrato luminescente em uma máquina chamada Vitros Eci foi usado para determinar a concentração de cortisol. O tempo de transição do pulso foi medido com fotopletismografia. Para análise estatística, os testes de Wilcoxon, U de Mann-Whitney e Anova de Friedman foram usados. Pressão arterial, pulso e concentrações de adrenalina, noradrenalina e cortisol foram medidos para estimar os efeitos simpáticos sistêmicos. RESULTADOS: receberam bupivacaína a 5% 40 pacientes do grupo controle e 40 do grupo teste receberam bupivacaína a 0,5% com cetamina S-(+). Um valor de p < 0,05 foi ...

JUSTIFICACIÓN Y OBJETIVOS: la ketamina S(+) es un anestésico intravenoso y simpaticomimético con propiedades de anestésico local. Posee un efecto analgésico y de anestésico local cuando se administra por vía epidural, pero no existen datos que informen si la ketamina S(+) en bajas dosis tiene efectos simpaticomiméticos. El objetivo de este estudio fue determinar si la ketamina S(+) en bajas dosis y administrada por vía epidural en combinación con el anestésico local tiene algún efecto sobre el sistema nervioso simpático, tanto sistémico como por debajo del nivel del bloqueo anestésico. MÉTODOS: el estudio fue realizado con 2 grupos de pacientes sometidos a anestesia epidural. A un grupo (grupo control) se le administró la anestesia local (bupivacaína al 0,5), mientras que a otro se le administró la anestesia local en combinación con la ketamina S(+). La edad, altura, peso, presión arterial sistólica y diastólica y la presión arterial media se midieron. El método inmunoquímico de inhibición enzimática no competitiva (Cat Combi ELISA) se usó para determinar las concentraciones de catecolaminas (adrenalina y noradrenalina). El ensayo inmunoenzimométrico con sustrato lumínico en una máquina llamada Vitros Eci fue usado para determinar la concentración de cortisol. El tiempo de transición del pulso fue medido usando la fotopletismografía. Para el análisis estadístico se usaron los test de Wilcoxon, U de Mann-Whitney y ANOVA de Friedman. La presión arterial, pulso y concentraciones de adrenalina, noradrenalina y cortisol fueron medidos para estimar los efectos simpáticos sistémicos. RESULTADOS: cuarenta pacientes del grupo control recibieron bupivacaína al 5% y 40 pacientes del grupo test recibieron bupivacaína al 0,5% con ketamina ...

Impairment of renal structure and function following heterogeneous chemical mixture exposure in rats.

Renal structural and functional alterations following an exposure to a heterogeneous chemical mixture (HCM) of phthalic acid di butyl ester, 1, 2–dichlorobenzene, cadmium chloride and chromium trioxide, administered through oral gavage in low doses (1/100 and 1/1000 of LD50 value of individual chemical) for 60 days, followed by withdrawal till 120 days resulted in significant rise in kidney lipid peroxidation and fall in the activities of enzymatic antioxidants. However, withdrawal of HCM treatment restored most of these altered parameters. Degenerative changes in the kidney included proximal convoluted tubules devoid of brush boarder with cytoplasmic blebbing, dissolution and sloughing of nuclei. Cortical glomeruli were also affected with epithelial disintegration, pyknosis of podocyte nuclei and mesengial cell hyperplasia. The morphological alterations recovered fully in the low dose compared to the high dose treatment group.

Effect of PCIA with Low-dose Fentanyl on Plasma Endothelin after Craniotomy / 昆明医科大学学报

Objective To investigate the effect of PCIA with low-dose fentanyl on plasma endothelin (ET) after craniotomy. Methods 47 cases of selected craniotomy were divided randomly into two groups :experimental group (26cases) and control group (21cases) . Patients in experimental group were treated with PCIA (fentanyl 15ug/kg +ondansetron 8 mg+100 mL NS) but patients in control group were not given PCIA. Then HR,MBP, VAS, ET and side-effects were observed and compared between two groups before treatment and 0, 2, 4, 8, 12, 24, 48 h after treatment.Results In experimental group, HR was lower at 2, 4, 8, 12, 24 and 48 h after treatment than control group. MBP was lower at 0 and 2h after treatment in experimental group than control group. Plasma levels of ET were lower at 8, 24 and 48h after treatment in experimental group than control group. There were significant differences in VAS scores at 2,4,8,12,24 and 48 h after treatment between two groups. There was no significant differences in side reactions including consciousness, respiratory depression, vomiting and sedation between two groups. The incidence of nausea was higher in experimental group than control group. Conclusion PCIA with low-dose fentanyl after craniotomy has good analgesic effect and few side reactions, can reduce the formation of plasma endothelin, and then alleviate brain damage.

Comparative study on the clinical outcome following different doses of amphotericin B liposome in the treatment of patients with invasive pulmonary fungal infections after renal transplantation / 中华器官移植杂志

ObjectiveTo compare the clinical effectiveness and adverse effects following low doses versus traditional doses of amphotericin B liposome (L-AmB) in the treatment of patients with invasive pulmonary fungal infections (IPFI) after renal transplantation.MethodsA total of 26 postrenal transplantation patients with IPFI between Jan. 2005 and Mar. 2011in Zhujiang hospital received L-AmB treatment identified low doses group (0.2-0.5 mg·kg-1·d-1,n =19) or traditional doses group (1-5 mg· kg-1,d-1,n =7) were reviewed.ResultsThe treatment duration in low doses group and traditional doses group was 20.3 +12.7 and19.3 ±13.2 days respectively (P＞0.05).The effective rate in low doses group and traditional doses group was 84.2％ and 57.1％ respectively (P＞0.05).The overall dosage was significantly less in the low doses group (414.7 ± 241.7 mg) than in the traditional doses group (1158.8 ± 928.0 mg) (P＜0.05).The incidence of adverse effect was significantly lower in the low doses group than in the traditional doses group (21.1％ vs.85.7％,P＜0.05).ConclusionThe effectiveness of low doses of L-AmB protocol in the treatment of IPFI postrenal transplantation patients was similar to that of traditional doses of L-AmB protocol,but the incidence of adverse effects in low doses of L-AmB protocol was significantly lower.

Efectos de dosis bajas de alcohol sobre la memoria declarativa en humanos / Effects of low doses of alcohol on declarative memory in humans

Se evaluó el efecto de 0, 0.035, 0.150, 0.300 g de alcohol sobre 2 componentes de la memoria explícita o declarativa, en 16 participantes, hombres y mujeres, mediante la aplicación de la prueba de textos del Weschler-III (WMS-III), utilizando un diseño factorial 2 x 4 de medidas repetidas contrabalanceadas. No se encontraron diferencias entre los sexos, pero sí entre las dosis, siendo 0.150 g de alcohol/kg de peso corporal la que más decrementó el recuerdo de episodios y de temas, especialmente a mediano plazo, con tamaños de los efectos de 43.9 y 62.9 %, respectivamente. Estos resultados confirman que el alcohol, aun en dosis bajas, deteriora más el componente semántico del recuerdo explícito, aproximadamente media hora después de su consumo.

This study assessed the effect of low doses of alcohol (0, 0.035, 0.150, 0.300 g) on two elements of explicit or declarative memory, in 16 participants, 8 women and 8 men, with The Weschler Memory Scale III Text Test. A factorial 2 * 4 counterbalanced with repeated measures design was used. There were no statistically significant differences by gender, but there were differences among doses, specially 0.150 g / kg., which reduced episodic and semantic retrieval, between 43.9 and 62.9 % of effect strength, in intermediate term memory. These results provided evidence that alcohol in low doses has a more pronounced effect in semantic, rather than episodic memory, in the middle term.

Dose-effect relationship of chromosome aberrations induced by different LET rays at low doses / 中华放射医学与防护杂志

Objective To establish the dose-effect curves of chromosome aberrations in human peripheral blood lymphocytes induced by different LET rays,including 60Co γ-rays,252Cf neutrons,14MeV neutrons and 12C heavy ions at low doses,respectively,in order to assess radiation-induced damages after occupational and accidental exposure.Methods Heparinized whole blood samples were irradiated with the various radiation devices and doses ranged from 0 to 1 Gy with the interval of 0.25 Gy.Conventional chromosome culture method was applied with adding colchicines at the beginning and chromosome specimens were prepared after 48 h incubation.The Metafer scanning system was used for automatical finder of chromosome metaphases.The mathematic models were fitted according to aberration data obtained.Results At the dose range of 0 - 1 Gy,the math models of dic + r were linear for 60 Co γrays and linear-quadratics for 252 Cf neutrons,14 MeV neutrons and 12 C heavy ions.The models of ace were linear-quadratic for 60Co γ-rays and 12C heavy ion beams,and linear for 252Cf and 14 MeV neutrons.The models of total aberrations were linear-quadratic for all types of radiation.Conclusions High LET rays have higher biological effects in inducing chromosome aberrations yields compared with low LET rays.Moreover,the severity of damage is 252Cf ＞ 14 MeV neutrons ＞ 12C heavy ions ＞ 60Co γ-rays in turn.Therefore,in the range of low doses,the dic + r may be a better target of radiation damage for high LET radiation.

Avaliação da exposição ocupacional, em laboratórios, de múltiplos agentes quimícos, por longo período e em baixas concentrações / Assessment of occupational exposure to multiple chemicals for a long period and in low concentrations in laboratories

Objetivo: Avaliar o perfil da exposição ocupacional a agentes químicos, em laboratórios, e verificar os impactos na avaliação de risco decorrentes das mudanças nos limites de exposição ocupacional (LEO) e na legislação federal brasileira. Metodologia: Revisão de literatura relativa a exposição ocupacional a substancias químicas, referentes a: conceituação de risco; desenho das curvas dose-resposta; identificação dos fatores que interferem na relação dose-efeito; conceitos de exposição por longo período, da exposição múltipla e em baixas concentrações; e fatores de confusão na monitoração ocupacional. Realização de estudo transversal no Centro de Pesquisas da Petrobrás, para avaliar o perfil de exposição a agentes químicos de 3.000 trabalhadores, com atividades preponderantes em laboratórios, metade das quais com exposição em baixas concentrações e por longo período, tendo por base as avaliações ambientais do ano de 2004. Analise temporal dos valores de LEO da American Conferrence of Governmental Industrial Hygienists (ACGIH) e levantamento das mudanças nas legislações federal previdenciária, trabalhista e de saúde nos aspectos relacionados o exposição a agentes químicos. Resultados: Foram identificadas 484 substancias químicas em 243 postos de trabalho, resultando em 2.550 situações de exposição, com media de 3,73 substancias químicas por local. Os 1.563 trabalhadores com exposição formaram 168 Grupos Homogêneos de Exposição (GHE), cuja composição variou de 1 a 44 trabalhadores (media de 4,55, mediana de 3 e moda de 1). Em cada local de trabalho foram identificados, em media, 4,91 GHE. Foram medidas 977 amostras. Com relação ao GHE, foi notado que em 91,9% das avaliações ocorreram resultados abaixo do nível de ação, correspondendo a 92,5% dos empregados, configurando a exposição a baixas concentrações. Verificou-se ainda que 49,6% dos GHE (49,9% dos empregados) tinham concentrações inferiores ao limite de detecção das técnicas analíticas, enquanto que em 8,1% dos GHE e 7,5% dos empregados, as concentrações estavam em nível igual ou acima do nível de ação. Comprovou-se que nos últimos dez anos foram implantados ou revisados 135 (18,5%) LEO. O número de substancias cuja redução do LEO e igual ou superior a 50% corresponde a quase totalidade das reduções e, em todos os períodos, as maiores sac iguais ou superiores a 80% ultrapassando, portanto, o nível de ação. Ainda que não exista concordância nos valores dos LEO foi constatado que, entre as diferentes agencias tem ocorrido freqüentes mudanças na legislação. Estes fatos tem obrigado os profissionais a incorporarem estes conhecimentos a sua pratica de trabalho. Conclusões: A exposição a substancias químicas em laboratórios e predominantemente em baixa concentração, variada e múltiplas. Na proteção da saúde de trabalhadores, a aceitação do risco quando a concentração ambiental da substancia química e abaixo do nível de ação, deve ser usado com parcim6nia, pois os valores de LEO tem apresentado tendência de redução e exclui parcela significativa da população...

Objective: The aim of this study was to assess the profile of occupational exposure to chemicals in laboratories and check the impacts on risk assessment that derive from changes in occupational exposure limits (OEl) and in Brazilian federal laws applicable thereto. Methodology: Review of publications on occupational exposure to chemicals concerning the following: risk concept, dose-response curve drawing, identifying factors that interfere with dose-effect relationship; concepts of lengthy exposure, multiple exposure, and low concentration exposure; confusing factors in occupational monitoring. A transversal study was carried out at the Petrobras Research Center in order to assess the profile of exposure to chemicals among 3,000 employees whose job was predominantly performed inside a laboratory, half of which were low concentration, lengthy exposures (the study was based on environmental assessments carried out in 2004). Time analysis of American Conference of Governmental Industrial Hygienists (ACGIH) OEl values. Survey on the changes made in security, labor, and health federal laws as relates to exposure to chemicals. Results: 484 chemicals were identified in 243 workplaces. This resulted in 2,550 exposure situations with an average of 3.73 chemicals per location. The 1,563 workers under exposure were divided into 168 Homogeneous Exposure Groups (HEG) comprised by 1 to 44 subjects (mean = 4.55; median = 3; mode = 1). On average, 4.91 HEG were identified in each workplace. 977 samples were measured. Regarding the HEG, it was observed that 91.9% of the assessments showed results below action level. This is equivalent to 92.5% of the amount of workers and fits into the low concentration exposure category. It was also observed that 49.6% of HEG (i.e. 49.9% of workers) showed concentrations lower than detection limit in analytical techniques, whereas concentrations were equal to or greater than action level among 8.1 % of HEG and 7.5% of workers. 135 (i.e. 18.5%) OEl were proven to have been implemented or revised. The amount of chemicals whose OEl decrease is equal to or greater than 50% is equivalent to nearly all decreases. Moreover, the highest decreases are equal to or greater than 80%, and therefore exceeded action level. Although there is no common agreement on OEl values, it was observed that applicable laws have been changed by several agencies on a regular basis. These facts have led professionals into considering such information in their work practice. Conclusions: Exposure to chemicals in laboratories occurs basically under low, varied, multiple concentration. In the field of workers' healthcare, one should be careful while considering a risk for environmental concentration of a chemical below action level. This is because OEl levels have shown to be prone to decrease and thus exclude a significant part of the population...