Resistance mechanisms of cereal plants and rhizosphere soil microbial communities to chromium stress.

Agricultural soils contaminated with heavy metals poison crops and disturb the normal functioning of rhizosphere microbial communities. Different crops and rhizosphere microbial communities exhibit different heavy metal resistance mechanisms. Here, indoor pot studies were used to assess the mechanisms of grain and soil rhizosphere microbial communities on chromium (Cr) stress. Millet grain variety 'Jingu 21' (Setaria italica) and soil samples were collected prior to control (CK), 6 hours after (Cr_6h), and 6 days following (Cr_6d) Cr stress. Transcriptomic analysis, high-throughput sequencing and quantitative polymerase chain reaction (qPCR) were used for sample determination and data analysis. Cr stress inhibited the expression of genes related to cell division, and photosynthesis in grain plants while stimulating the expression of genes related to DNA replication and repair, in addition to plant defense systems resist Cr stress. In response to chromium stress, rhizosphere soil bacterial and fungal community compositions and diversity changed significantly (p < 0.05). Both bacterial and fungal co-occurrence networks primarily comprised positively correlated edges that would serve to increase community stability. However, bacterial community networks were larger than fungal community networks and were more tightly connected and less modular than fungal networks. The abundances of C/N functional genes exhibited increasing trends with increased Cr exposure. Overall, these results suggest that Cr stress primarily prevented cereal seedlings from completing photosynthesis, cell division, and proliferation while simultaneously triggering plant defense mechanisms to resist the toxic effects of Cr. Soil bacterial and fungal populations exhibited diverse response traits, community-assembly mechanisms, and increased expression of functional genes related to carbon and nitrogen cycling, all of which are likely related to microbial survival during Cr stress. This study provides new insights into resistance mechanisms, microbial community structures, and mechanisms of C/N functional genes responses in cereal plants to heavy metal contaminated agricultural soils. Portions of this text were previously published as part of a preprint (https://www.researchsquare.com/article/rs-2891904/v1).

Trends in work-related respiratory diseases attributed to nickel, chromium and cobalt in the UK: descriptive findings from The Health and Occupation Research (THOR) network 1996-2019.

BACKGROUND: Occupational exposure to metals can be associated with respiratory diseases which can adversely affect the individual's health, finances and employment. Despite this, little is known about the incidence of these respiratory conditions over prolonged periods of time. AIMS: This study aimed to investigate the trends in the incidence of work-related respiratory diseases attributed to nickel, chromium and cobalt in the UK. METHODS: Cases of occupational respiratory diseases caused by nickel, chromium or cobalt reported to Surveillance of Work-related and Occupational Respiratory Disease (SWORD), the UK-based surveillance scheme between 1996 and 2019 (inclusive), were extracted and grouped into six 4-year time periods. Cases were characterised by causative metal exposure, occupational and industrial sector. Incidence rates diseases (adjusted for physician participation and response rate) were calculated using ONS employment data. RESULTS: Of cases reported to SWORD during the study period, 1% (173 actual cases) of respiratory problems were attributed to nickel, chromium or cobalt. Diagnoses of asthma compromised the largest proportion of diagnoses (74.4%), followed by lung cancer (8.9%) and pneumoconiosis (6.7%). Cases had a mean age of 47 years (SD 13); 93% were men. The annual incidence fell from 1.6 per million employed in the first 4-year period, to 0.2 in the most recent period. CONCLUSIONS: Over 24 years, a decline in the incidence of metal-related occupational respiratory diseases was observed in the UK. This could be attributed to improvements in working conditions which resulted in reduced metal exposure but could also be due to closure of industries that might have generated case returns.

Cardiac function may be compromised in patients with elevated blood cobalt levels secondary to metal-on-metal hip implants.

Aims: Elevated blood cobalt levels secondary to metal-on-metal (MoM) hip arthroplasties are a suggested risk factor for developing cardiovascular complications including cardiomyopathy. Clinical studies assessing patients with MoM hips using left ventricular ejection fraction (LVEF) have found conflicting evidence of cobalt-induced cardiomyopathy. Global longitudinal strain (GLS) is an echocardiography measurement known to be more sensitive than LVEF when diagnosing early cardiomyopathies. The extent of cardiovascular injury, as measured by GLS, in patients with elevated blood cobalt levels has not previously been examined. Methods: A total of 16 patients with documented blood cobalt ion levels above 13 µg/l (13 ppb, 221 nmol/l) were identified from a regional arthroplasty database. They were matched with eight patients awaiting hip arthroplasty. All patients underwent echocardiography, including GLS, investigating potential signs of cardiomyopathy. Results: Patients with MoM hip arthroplasties had a mean blood cobalt level of 29 µg/l (495 nmol/l) compared to 0.01 µg/l (0.2 nmol/l) in the control group. GLS readings were available for seven of the MoM cohort, and were significantly lower when compared with controls (-15.5% vs -18% (MoM vs control); p = 0.025)). Pearson correlation demonstrated that GLS significantly correlated with blood cobalt level (r = 0.8521; p < 0.001). However, there were no differences or correlations for other echocardiography measurements, including LVEF (64.3% vs 63.7% (MoM vs control); p = 0.845). Conclusion: This study supports the hypothesis that patients with elevated blood cobalt levels above 13 µg/l in the presence of a MoM hip implant may have impaired cardiac function compared to a control group of patients awaiting hip arthroplasty. It is the first study to use the more sensitive parameter of GLS to assess for any cardiac contractile dysfunction in patients with a MoM hip implant and a normal LVEF. Larger studies should be performed to determine the potential of GLS as a predictor of cardiac complications in patients with MoM arthroplasties.

Is there still an indication for the Birmingham Hip Resurfacing in femoral head osteonecrosis?

PURPOSE: Osteonecrosis of the femoral head (ONFH) is a progressive hip disease. Hip resurfacing arthroplasty (HRA) is a preferred surgical procedure among hip arthroplasty performed in young patients. The aim of this study is to show the long-term clinical and radiological results of HRA procedures performed for patients suffering from ONFH. METHODS: Forty-five patients who underwent hip resurfacing with the diagnosis of femoral head osteonecrosis were included in the study. The Harris Hip Score (HHS) was used for clinical scoring of the patients. The blood chromium, cobalt, white blood cell (WBC) count, and CRP levels of patients were checked. Ultrasonography (USG) was performed for all patients at mid-term control checked for pseudo-tumours. For the radiological evaluation, acetabular inclination, stem shaft angle, prothesis-to-neck ratio, osteolysis zones, and heterotopic ossification were used. RESULTS: The mean age of the patients was 46.6 ± 9.3 years, and the mean follow-up period was 11.83 ± 2.9 years. The mean HHS was 90.3 ± 12.8 for final follow-up. The mean WBC value was 8.2 109/L, mean CRP value was 6.3 mg/L, mean chromium value was 4.9 µg/L, and mean cobalt value was 1.8 µg/L. Inclination changing 0.2°(p = 0.788), stem shaft angle changing 0.7°(p = 0.424), and neck-to-prosthesis ratio changing 0.01°(p = 0.075). No pseudo-tumours were detected in any patients in USG examination. CONCLUSION: HRA provides long-term implant survival and excellent clinical outcomes for end-stage ONFH patients with low complication rates.

Assessing the health risks of dermal exposure to heavy metals dust among nail salon technicians.

BACKGROUND: Nail salon technicians are susceptible to potential exposure to a diverse array of hazardous chemicals in the form of dust or vapors. One of the main routes of exposure is dermal contact. OBJECTIVE: The aim of present study was to health risk assessment of dermal exposure to dust containing heavy metals in nail salon technicians. METHODS: Dust sampling was done on the work surface of 20 available nail salon technicians. The concentration of five metals including cadmium, lead, chromium, nickel, and manganese were determined using ICP-MS. Afterwards, the United States Environmental Protection Agency (USEPA) guideline was used to estimate the potential health risks, including carcinogenic and non-carcinogenic risks, associated with the analyzed metals. RESULTS: Results indicated the mean concentrations of Pb, Cd, Ni, Cr and Mn were 0.7953±0.4373, 0.0952±0.0264, 0.7666±0.8629, 0.4900±0.5994 and 1.134±0.4736, respectively. The hazard quotient (HQ) of all metals was within the permissible value, while hazard index (HI) was greater than 1. The probability of cancer risk (CR) resulting from dermal exposure to Ni, Cd and Cr exceeded the acceptable risk levels (10-6-10-4), but CR calculated for Pb was less than allowable value. CONCLUSION: Implementation of engineering controls such as downdraft vented nail tables and portable source capture systems is necessary. Besides, the use of personal protective equipment such as disposable nitrile gloves, N95 respirator masks, and ensuring proper training on safe work practices is recommended.

The association of cobalturia with cobaltism symptoms a prospective blinded study of 229 post-arthroplasty patients.

INTRODUCTION: Cobalt is a mitochondrial toxin, clinical cobaltism manifests with constitutional, neurologic, and cardiovascular symptomatology. Cobalt's severe toxidrome is known through case reports from extreme wear or corrosion of cobalt-chromium arthroplasty components. However, the spectrum and epidemiology of orthopedic-implant cobaltism and its relationship to duration and degree of cobalt exposure are not well defined. METHODS: The relationship of urine-cobalt concentration and duration of exposure to cobalt-chromium joint implants and cobaltism symptomatology were prospectively studied in 229 patients. Subjects received a Cobaltism-Symptom-Inventory-Score (CSIS) based on a protocolized interview and examination followed by a spot urine-cobalt measurement. RESULTS: 129 (56%) subjects were cobalturic (urine-cobalt ≥1.0 ppb). 122 (53%) subjects had a CSIS of >2, this status significantly associates with cobalturia. Median [IQR] urine-cobalt in the subjects with a CSIS >2 was 4.1[1.1-17.0] ppb compared to 0.5[0.5-1.4] ppb in subjects with CSIS ≤ 2. Cobalturia has a sensitivity of 0.69, a specificity of 0.77, and a positive predictive value of 0.74 for a CSIS of >2. The product of years-exposed to a cobalt-chromium implant and urine-cobalt by quartiles significantly positively associates with the Cobaltism-Symptom-Inventory-Score. CONCLUSION: A urine-cobalt of ≥1 ppb likely indicates adverse systemic exposure to orthopedic-implant generated cobalt. Cobaltism severity as quantified by the CSIS significantly correlates with the product of spot urine-cobalt concentration and years-exposed to a cobalt-chromium orthopedic-implant indicating a dose-response relationship. Medical provider and public awareness of orthopedic-implant cobaltism is vital because tens-of-millions are at-risk and early cobaltism is reversible. Further use of cobalt-chromium orthopedic-implants should be questioned given cobaltism becomes clinically apparent at a spot urine-cobalt of 1 ppb or greater. Monitoring of patients with high-risk cobalt-chromium orthopedic-implants appears to be indicated.

Nickel, chromium and cobalt: the relevant allergens in allergic contact dermatitis. Comparative study between two periods: 1995-2002 and 2003-2015

Abstract: Background: Metals are common agents of allergic contact dermatitis, occupational or not, with decreasing incidence over the last years in some countries that have regulated the amount of nickel in objects. Objectives: To analyze and compare with previous studies the profile of metal sensitization between 2003-2015. Methods: Patients who underwent patch testing between 2003-2015 were evaluated retrospectively regarding the sensitization rates to metals, the associations between them, the relationship with profession and epidemiology. Results: Of the 1,386 patients tested, 438 (32%) had positive test to some metal, similar results to the 404/1,208 (33%) of the previous study (1995-2002) performed at the same service (p=0.32). The frequency of nickel (77%), cobalt (32%) and chromium (29%) changed slightly (p=0.20). Most cases of sensitization to chromium were related to the occupation (64%), in contrast to nickel and cobalt (p<0.0001). There was a predominance of females among those sensitized to metal in both studies (p=0.63) and the age group of 20-49 years old (p=0.11); the number of fair-skinned individuals increased (p<0.001), as well as the lesions in the cephalic segment (50.5%; p<0.0001) and hands (45%; p<0.0001), which are not the most frequent location anymore. The number of cleaners decreased (39% vs. 59%; p<0.0001), which still lead in front of bricklayers/painters, which increased (14% vs. 9%; p=0.013). The frequency of wet work reduced (65% vs. 81%; p<0.0001). Study limitations: The study included a single population group; only patients with positive tests to metals were considered - the others were not evaluated for the possibility of false negatives. Conclusion: The sensitization to metals, occupational or not, has been significant over the last 21 years, with few epidemiological changes.

Epidemiological analysis of occupational dermatitis notified in Brazil in the period 2007 to 2012

Abstract: BACKGROUND: Occupational dermatitis affects the quality of life and productivity of workers. Studies on the subject are scarce in Brazil. It is estimated that the disease is underreported and that many affected patients do not seek health care. OBJECTIVES: To conduct an epidemiological analysis of occupational dermatitis notified via SINAN in Brazil from January 2007 to December 2012; evaluate the profile of patients assisted; and check the main etiological agents involved. METHODS: We analyzed the compulsory notification forms of cases of occupational dermatitis filled nationwide during January 2007 to December 2012. RESULTS: During the study period 3027 cases of occupational dermatitis were notified in Brazil. In 61.4% of cases patients were men aged between 35-49 years (39.6%). The most described etiological agent was chromium (13.9%). The location of the body most affected was the hands, with 28.4% of cases. The construction sector is implicated in 28.7% of cases and domestic services by 18%. Allergic contact dermatitis is the most prevalent occupational dermatitis (20.6%) and the region with the highest number of notifications was the Midwest, with 376.4 cases per million inhabitants. CONCLUSIONS: The profile of patients most affected by occupational dermatitis in Brazil during the study period was: men with elementary school, aged between 20 and 49 years old and working in the construction industry. The most common occupational dermatitis were allergic contact dermatitis caused by chromium after years of exposure, being the hands and head the parts of the body most affected.

Contact sensitivity to metals (chromium, cobalt and nickel) in childhood / Alergia de contato aos metais (cromo, cobalto e níquel) na infância

Metals, especially nickel, are the most common contact allergens in children. Recent data has shown increased incidence of allergy in industrialized countries. Sensitization can occur at any age, even in neonates. Costume jewelry, particularly earrings, is linked to increased sensitization to nickel. Sensitization to cobalt often occurs by the use of costume jewelry. The most common source of sensitization to chromium is leather. Due to the absence of a specific therapy, the main treatment is to identify and avoid the responsible allergens. This article presents an updated view on the epidemiological and clinical aspects of contact allergy to metals, focusing on prevention strategies and risk factors, and warns about possible and new sources of contact.

Os metais, especialmente o níquel, são os sensibilizantes de contato mais comuns em crianças. Dados recentes revelam aumento na incidência da alergia deste em países industrializados. A sensibilização pode ocorrer em qualquer idade, mesmo em recém-nascidos. Bijuterias, especialmente brincos nas orelhas, são ligadas ao aumento da sensibilização ao níquel. A sensibilização ao cobalto geralmente ocorre pelo uso de bijuterias. A fonte mais comum de sensibilização ao cromo é o couro. Devido à ausência de terapia específica, o principal tratamento consiste em identificar e evitar os alérgenos responsáveis. Este artigo pretende apresentar uma visão atualizada sobre os aspectos epidemiológicos e clínicos da alergia de contato aos metais, focando estratégias de prevenção e fatores de risco, além de alertar sobre as possíveis e novas fontes de contato.

Biosorption of lead(II) and chromium(VI) on groundnut hull: equilibrium, kinetics and thermodynamics study / Biosorción de plomo (II) y cromo (VI) en cáscaras de maní: estudio de equilibrio, cinética y termodinámica

The biosorption of lead(II) and chromium(VI) on groundnut hull was investigated. Batch biosorption experiments were conducted to find the equilibrium time and biosorption capacity. Effect of parameters like pH, temperature and initial metal concentration was studied. The maximum biosorption capacity of lead(II) and chromium(VI) was found to be 31.54 +/- 0.63 and 30.21 +/- 0.74 mg g-1, respectively. The optimum pH for lead(II) and chromium(VI) removal was 5 ± 0.1 and 2 +/- 0.1, respectively. The temperature change, in the range of 20 - 45ºC affected the biosorption capacity. The maximum removal of lead(II) was achieved at 20 +/- 2ºC, where as maximum uptake of chromium(VI) was observed at 40 +/- 2ºC. The biosorption data was fitted to the Langmuir and the Freundlich isotherm models. The Langmuir model showed better representation of data, with correlation coefficient greater than 0.98. The kinetics of biosorption followed the pseudo second order kinetics model. The thermodynamics parameters were evaluated from the experimental data.

Uso do óxido crômico e do LIPE® na estimativa do consumo de matéria seca por bezerros de corte / Use of chromic oxide and LIPE® as external markers to estimate dry matter intake by beef calves

Avaliou-se a eficiência do óxido crômico e da lignina purificada e enriquecida (LIPE®), fornecidos uma vez ao dia, para a estimativa do consumo de matéria seca (CMS). Foram utilizados 12 bezerros de corte, de ambos os sexos, com uma média de idade de 210 dias e peso médio de 168kg, pastejando Brachiaria decumbens, distribuídos em um delineamento inteiramente ao acaso, em esquema de parcelas subdivididas. Os valores estimados de consumo, entre machos e fêmeas, foram semelhantes nos dois tratamentos. Entre os indicadores, as estimativas, da produção fecal e do consumo, foram menores para o óxido crômico. O CMS de forragem, o CMS total, o CMS em relação ao peso vivo e o CMS em relação ao peso metabólico, estimados pelos indicadores óxido crômico e LIPE®, foram, respectivamente, 2,03 e 4,50kg; 2,71 e 5,18kg; 1,62 e 3,10 por cento e 58,10 e 111,32g/kg PV0,75. O consumo estimado pelo LIPE® foi mais condizente com as exigências e com o desempenho observado nos animais.

Six male and six female calves, seven-month-old, averaging 168kg bw, grazing on Brachiaria decumbens, were used in a split plot design to compare the efficacy of two external markers: chromic oxide (Cr2O3) and purified and enriched lignin (LIPE®) simultaneously dosed once a day to predict dry matter intake (DMI). For both, Cr2O3 and LIPE®, no differences in DMI according to gender were observed. Comparing the efficacy of the two markers to predict fecal output and pasture intake, the estimates obtained with chromic oxide were lower. Forage DMI, total DMI, DMI as percentage of body weight, and DMI in relation to metabolic weight were: 2.03 and 4.50kg; 2.71 and 5.18kg; 1.62 and 3.10 percent, and 58.10 and 111.32g/kg bw0.75 for Cr2O3 and LIPE®, respectively. These results suggest that estimates obtained from LIPE® were more appropriate to the dry matter requirements and performance of the calves.

Evaluación de la exposición ocupacional a cromo en industrias de cromado en Valencia, Venezuela / Assessment of the occupational exposure to chromium in chromium-industries in Valencia, Venezuela

Twenty three (23) workers were studied in 2 plating industries: hard-surface plating (A); n=20 and decorative plating (B); n=3, to characterize potential health effects due to Chromium (Cr) exposure. A questionnaire was designed to collect personal data, health information, work activities and life-styles. Personal Cr+6-Air and biological monitoring of Initial and Final Cr in Urine (U-Cr), were conducted. Results show that A had workers with a higher mean of Cr+6-Air than B, but the difference was no statistically significant which was not expected due to the type of process. The average concentration of U-Cr Initial and Final, on workers with “Direct” exposure (15 workers) was significantly higher (p=0,005; y p=0,008 respectively) to the workers with “Indirect” exposure (8 workers) as it was expected. At “A”, the mean concentration of Initial U-Cr in chroming workers (13,98 ± 8,78 ug/g Ct), was significantly higher (p=0,012) to the one obtained with workers of the Administrative area (2,53 ± 1,7 ug/g Ct). Maintaining mechanics (MM) mean (13 ± 5,57 ug/g Ct) was significantly higher to the level obtained from Operator (O) (6,04 ± 1,78 ug/g CT) and Administrative area workers (2,53 ± 1,7 ug/g ct), (p=0,047 y p=0,004 respectively). This can be explained because MM and O are exposed “directly” working very near to the chromium piles. Main symptoms reported were dermal (65,2 percent) and respiratory (30,4 percent), which are the most vulnerable systems to Cr. The association of biological and environmental monitoring, show a direct correlation (r=0.373), and significant (p=0,04), however, the Cr+6-Air level was not able to explain with confidence, the variability in U-Cr concentrations. It is recommended a new study with a more frequent sampling during the day and more extended in time.

Se realizó un estudio de corte transversal en 2 empresas cromadoras de Valencia, Venezuela, para evaluar posibles efectos adversos por exposición al Cromo (Cr). Se investigaron 23 trabajadores, 20 de cromado duro (A) y 3 de cromado decorativo (B). Se administró un cuestionario para conocer datos personales, clínicos, estilos de vida y prácticas de trabajo. Se utilizaron monitores personales para determinar la concentración ambiental de Cr+6 (Cr+6-aire) y se midió la concentración de Cr en Orina (Cr-O), Inicial y Final. Aunque los valores de Cr-Aire en la empresa “A” resultaron levemente superiores a los de “B”, realmente se esperaba que, basados en el tipo de proceso, fuesen significativamente mayores em “A”. El promedio de Cr-O Inicial y Final en trabajadores com exposición “Directa” (15 Trabajadores), fue significativamente superior (p=0,005; y p=0,008 respectivamente) a los de exposición “Indirecta” (8 trabajadores), como se esperaba. En la empresa “A” la media de Cr-O inicial observada en los cromadores (13,98 ± 8,78 ug/g Ct), fue significativamente superior (p=0.012) a la media obtenida en los trabajadores Del área Administrativa (2,53 ± 1,7 ug/g Ct) y la de los Mecánicos de Mantenimiento (MMTO) (13 ± 5,57 ug/g Ct), fue significativamente superior a la de Tornero/Operador (TO) (6,04 ± 1,78 ug/g Ct) y Administrativos (2,53 ± 1,7 ug/g Ct), (p=0,047 y p=0,004 respectivamente). Los valores Del cromador, MMTO y TO se explican porque son de exposición “Directa”, con puesto de trabajo muy cercano a las pilas de cromado. Los síntomas principales reportados en la población general fueron dérmicos (65,2 por ciento), seguidos por respiratórios 30,4 por ciento, que son los sistemas más vulnerables al Cr Al asociar indicadores biológicos y monitoreo ambiental, los resultados muestran una correlación...

Action of trivalent chromium on rat liver structure. Histometric and haematological studies

RESUMEN: El cromo trivalente (Cr3+) es un nutriente esencial involucrado en la regulación del metabolismo de carbohidratos, lípidos y proteínas, a través de un estímulo a la acción de la insulina. El objetivo del presente trabajo fue caracterizar histopatológicamente e histométricamente las alteraciones hepáticas de ratas Wistar hembras, provocadas por la administración de cromo III en agua potable. Ratas adultas recibieron ración y agua potable ad libitum, conteniendo 300 ó 500 mg/l de cromo III, durante 4 meses. Los animales control recibieron solo agua y ración. Todos los animales fueron sacrificados con dosis letal de anestésico. Muestras de hígado, fijadas en formol al 10% por 24 h, fueron cortadas a 6 µm y teñidas con hematoxilina y eosina o PAS. Además del examen histopatológico, fueron usadas técnicas histométricas. La sangue fue recolectada y procesada para estudio hematológico. El análisis histopatológico reveló, en la zonas periportal, intermediaria y pericentrolobular, células parenquimatosas con grados variables de vacuolización. Muchos hepatocitos mostraban degeneración baloniforme con núcleos lisados. La vena centrolobular estaba dilatada y congestionada. Se observaron sinusoides dilatados conteniendo eritrocitos. La zona porta mostró fibrosis y proliferación de ductos biliares con pequeñas células. La histometría mostró aumento de los volúmenes de citoplasma y celular, y valores menores para el número de hepatocitos por mm3. Linfopenia fue observada en los animales tratados con 500 mg/l de Cr3+. Estos resultados indican que el cromo III tiene una participación directa en las alteraciones de las estructuras hepáticas.

Efeitos do cobre e cromo na comunidade zooplanctônica: um estudo experimental em mesocosmos / Effects of copper and chromium on the zooplankton community: a mesocosms experimental study

O crescente desenvolvimento industrial e urbano tem acarretado a introdução de grandes quantidades de metais nos ecossistemas aquáticos, expondo, potencialmente, sua biota e toda a cadeia alimentar que dela se origina à contaminação por esses elementos. O objetivo deste trabalho foi avaliar os efeitos dos metais cromo e cobre sobre a estrutura da comunidade zooplanctônica de espécies holo-zooplanctônicas em experimentos de mesocosmos realizados na Represa do Lobo-Broa (CHREA/USP). Na análise das amostras de zooplâncton foram contadas e identificadas as espécies dos três principais grupos zooplanctônicos (Copepoda, Cladocera e Rotifera), quantificados os ovos e classes populacionais de Cladocera e Copepoda, e posteriormente feitos os cálculos de diversos índices ecológicos. Os resultados obtidos indicam que as concentrações dos metais aplicadas causaram efeitos sobre a comunidade zooplanctônica. No entanto, estes efeitos foram diferenciados entre os diversos grupos e espécies observadas, sendo que para avaliar os efeitos sub-letais, uma análise populacional demonstrou ser mais eficiente do que índices ecológicos gerais. Apesar dos índices ecológicos terem demonstrado que os efeitos da contaminação por cromo foram mais severos sobre a comunidade zooplanctônica em relação ao cobre, os microcrustáceos apresentaram um melhor desenvolvimento no tanque contaminado cromo, sendo estes efeitos diferentes para as diversas espécies. Foram observadas alterações na abundância, produção e estoque de ovos de Calanoida, com efeito mais pronunciado no tanque contaminado com cobre. Os Cyclopoida foram mais resistentes à contaminação pelos metais, porém apresentaram sensibilidade diferenciada entre as espécies e entre os estágios de desenvolvimento. Em geral, os cladóceros foram mais sensíveis à contaminação, com efeito tóxico agudo em várias espécies, e efeitos crônicos para ambos os metais, avaliados pela redução no desenvolvimento e produção de ovos. Foram observadas ainda diferenças na sensibilidade entre as espécies de Cladocera, e a competição por recursos demonstrou ser um fator importante na sucessão de espécies nos mesocosmos. O cromo causou efeitos tóxicos mais acentuados sobre a maioria das espécies de Rotifera. A competição por recursos e a predação sobre Rotifera foram fatores importantes na estruturação de suas populações, sendo bastante influenciadas por efeitos indiretos causados pela contaminação do meio.

Lesões agudas da mucosa gastroduodenal por ingestão acidental de cromo / Acute gastroduodenal mucosal injury by accidental ingestion of chromium

O cromo é um elemento amplamente difundido na natureza, e utilizado em diversos processos industriais. Pode ocorrer em diversas valências, sendo as mais importantes a trivalente e a hexavalente. Na forma trivalente, é um nutriente essencial, fazendo parte do fator de tolerância à glicose. Na forma hexavalente, apresenta ação irritativa e corrosiva para a pele, trato respiratório e trato gastrointestinal, é sensibilizante para a pele e o aparelho respiratório e carcinogênico para os pulmões. Lesões cutâneas são descritas em trabalhadores das indústrias química, têxtil, naval, de cromação, de tratamento de madeiras e de curtição de couro, em pintores, galvanizadores e operários da construção civil. Asma ocupacional, bronquite e enfizema pulmonar podem ocorrrer em soldadores, trabalhadores das indústrias química, de cimento e cromagem. Estes apresentam, também, um risco aumentado de carcinoma broncogênico. A ingestão de cromo pode levar a gastroenterite e sangramento gastrointestinal. Uma vez absorvido, o cromo pode produzir lesão hepática e tem como órgão alvo os rins, levando a insuficiência renal aguda. O tratamento desses quadros agudos, baseia-se principalmente em medidas de suporte, hemodiálise e administração de altas doses de ácido ascórbico. O autor relata o caso de um operário de uma indústria química que apresentou um quadro pouco comum de intoxicação por ingestão acidental de água contaminada por cromo hexavalente, evoluindo com lesões agudas da mucosa gastroduodenal, com evidências laboratoriais de comprometimento hepático discreto e mínima alteração da função renal. Na revisão bibliográfica dos últimos dez anos, não foi encontrado qualquer relato de caso com evolução semelhante.

Riscos ocupacionais e cancer de pulmao / Occupational risks and lung cancer

O objetivo deste trabalho é revisar o tópico dos riscos ocupacionais e câncer de pulmäo. Inicialmente, situa-se a importância do câncer de pulmäo no contexto dos cânceres na populaçäo brasileira. Discute-se tendências da incidência da doença em nível mundial, observando-se que os estudos apontam para maior ocorrência nas regiöes mais industrializaas e urbanizadas. Säo discutidas as dificuldades dos estudos epidemiológicos para identificar cancerígenos ocupacionais para o pulmäo, considerando-se aspectos como a multicasualidade envolvida na doença, o período de latência e a intensidade da exposiçäo. É enfocada a associaçäo de determinados fatores causais como tumores pulmonares de tipos histológicos específicos. Discute-se, a seguir, o papel de alguns agentes físicos e químicos ocupacionais, assumidos como mais relevantes, na gênese do câncer de pulmäo: radiaçöes ionizantes, arsênico, asbesto, berílio, cromo, ferro, níquel, clorometil éteres e hidrocarbonetos policíclicos. Säo discutidos ainda determinados processos de trabalho aos quais têm sido associados frequências altas de neoplasia pulmonar. Finalmente, é salientada a importância da prevençäo primária para o controle do câncer de pulmäo de origem ocupacional, tendo em vista o pouco impacto decorrente das prevençöes secundárias e terciárias

Metales pesados en el río Reconquista (Buenos Aires): resultados preliminares / Heavy metal in the Reconquista river (Buenos Aires): priliminary results

Entre agosto de 1986 y febrero de 1987 se colectaron mensualmente alícuotas de agua superficial del río Reconquista (Pcia. de Buenos Aires). Los muestreos se efectuaron en dos zonas estacionales: Cascallares (E1) y Bancalari (E2). En la primera, el río no ha cruzado aún la zona industrial-urbana y la segunda corresponde a un punto próximo a la desembocadura. Se determinó la concentración total de Zn, Cr y Cd disueltos, por espectrofotometría de absorción atómica. El único metal presente, en forma casi constante, fue el Zn. Su concentración resultó generalmente mayor en E2 y los valores más altos (4mg/l) fueron encontrados en verano. Aún en E1 las concentraciones de este metal sobrepasan los límites superiores citados para ríos no contaminados. El Cr y Cd no fueron hallados en forma regular en las muestras analizadas.