Biological Limits Research Articles

Distribution and Settling Regime of Transparent Exopolymer Particles (TEP) Potentially Associated With Bio‐Physical Processes in the Eastern Indian Ocean

AbstractThe detailed transparent exopolymer particles (TEP) distribution, sinking behavior and the potential mechanisms behind that were revealed in the upper 200 m water column of the eastern Indian Ocean (EIO). The biological process and nutrient limitation have proved to be non‐negligible, both of which possessed potential functions in controlling the TEP pool. TEP production and fate presented significant subregional variations in the study area. The vertical distributions of TEP displayed coherent declined patterns with depth between the marginal sea and pelagic ecosystems, but the concentration of TEP horizontally decreased from marginal sea to open ocean. Dissimilarly, variable distribution patterns and magnitudes were distinguished between stratified and active current zones with the conclusion that the stratified condition was in favor of downward remove of TEP pool but turbulence facilitated the accumulation of TEP especially in the deep chlorophyll maximum (DCM) layer. Distinct sinking regimes of TEP in the stratified zone were distinguishable between layers, with the regulatory mechanisms in the upper, DCM and lower layer of water column being physical diffusion of denser seawater and solutes, aggregation by biotic and abiotic processes and buoyancy effect by entrained lighter fluid, respectively. By comparing the theoretical and measured sinking rates of TEP‐formed aggregates and considering the complicated and uncontrollable situations in non‐culture scenarios, the coupling effects of physical and biological variables on TEP dynamics were elucidated, thus providing a compelling theory for predicting the downward fate of carbon flux in the field environments.

N-Methylformamide. Documentation of proposed values of occupational exposure limits (OELs)

N-Methylformamide is a colorless liquid with an ammoniacal odor, used as a solvent and an intermediate for chemical reactions. There are no data on occupational exposure in Poland. N-Methylformamide is very well absorbed into the human body. The LD50 values for N-methylformamide administered to animals in various routes are similar (2600 ÷ 4000 mg/kg bw). After single or short-term administration of the compound in doses of 100 ÷ 1200 mg/kg bw. worsening symptoms of liver damage have been observed. No-observed adverse effect concentration (NOAEC) was established at 120 mg/m3 (two-week inhalation exposure in rats). Increase of hepatotoxic effect of N-methylformamide were observed at concentrations of 320 mg/m3 and 980 mg/m3. There are no data on sub-chronic, chronic and carcinogenic effects of the compound in laboratory animals. N-Methylformamide was not mutagenic and genotoxic. It caused embryotoxic and teratogenic effects. The NOAEC value (120 mg/m3) was used as the basis for determining the MAC (maximum acceptable concentration) value for N-methylformamide, and the MAC value for N-methylformamide was calculated at 3.3 mg/m3. There are no basis to determine the short-term value (STEL) and biological limit value (BLV). It has been proposed to label the compound as "Ft" (toxic for reproduction) and "skin" (skin absorption of the substance may be as important as inhalation exposure). This article discusses the problems of occupational safety and health, which are covered by health sciences and environmental engineering

Deconstructing agronomic resource use efficiencies to increase food production

Food production per unit land area needs to be increased, thus cropping systems need to use nutrients, water and solar radiation at as close to maximal efficiencies as possible. We deconstruct these efficiencies into their components to define a theoretical crop ideosystem, in which all resource use efficiencies are maximised. This defines an upper biological limit to food production. We then quantify the difference between maximum use efficiencies and those observed in three agronomic systems (maize, cocksfoot, sugarcane) and identify how, in actual farm systems, efficiencies can be raised to raise food production. We find that crop nutrient use efficiency can be limited by low water availability; thus adding nutrients would not raise production but adding water would. The converse situation of water use efficiency being affected by nutrition is not as evident. Ideosystem thinking can be used to define small- and large-scale agronomic systems that optimize water and nutrient use to maximise food production. Highlights - Novel ideosystem method of analysing processes of food production, focussing on resource use efficiencies. - Interactions between resource use efficiencies are asymmetrical. - The ideosystem concept portrays how far a production system approaches maximum efficiency.

Biologics for Treatment of Atopic Dermatitis: Current Status and Future Prospect

Atopic dermatitis (AD) is a common inflammatory skin disease characterized by intense pruritus and recurrent eczematous lesions that significantly impair quality of life. It is a heterogeneous disease affecting both children and adults. The treatment of moderate-to-severe forms of AD is challenging, as topical corticosteroids are often insufficient to achieve disease control or inappropriate and off-label use of immunosuppressants may have significant undesirable side effects. The development of targeted biologic therapies specifically for AD is thus highly desirable. Dupilumab is the only biologic therapy that is Food and Drug Administration approved for the treatment of moderate-to-severe AD in patients 6 years and older, with consistent long-term efficacy and safety trial data. In this article, we review the mechanisms, safety, and efficacy of dupilumab from recent clinical trials, and we review the current data, mechanism of action, clinical efficacy, and limitations of new biologics currently in phase 2 and 3 clinical trials (lebrikizumab, tralokinumab, nemolizumab, tezepelumab, and ISB 830).

The Hitchhiker's Guide to Hydrogen Peroxide Fumigation, Part 2: Verifying and Validating Hydrogen Peroxide Fumigation Cycles.

Introduction: Part 1 of this two-part series describes the use of hydrogen peroxide as a fumigant and compares it with other fumigants on the market. Technical requirements are outlined while considering physical and biological limitations of the system. This second part focuses primarily on the use of process controls to verify and validate hydrogen peroxide fumigations. Finally, a model encompassing the entire fumigation process is presented. Methods: Part 2 of the series focuses on the authors' long-time personal experiences in room and filter fumigation using various fumigation systems and is supplemented with relevant literature searches. Results: The reader is introduced to the planning and implementation of fumigation process validations. Biological indicators help users develop safe and efficient processes. Chemical indicators can be used as process controls, while measuring physical parameters will help avoid condensation of hydrogen peroxide. How many biological and chemical indicators and what type should be applied for cycle development are additionally explained. Discussion: It is important to consider numerous technical requirements when planning to implement hydrogen peroxide fumigation at an institution. Also, considerable thought needs to go into the verification and validation of the fumigation process. Conclusions: Part 1 of this series presents an overview of different fumigation systems based on hydrogen peroxide on the market and their technical requirements. Part 2 focuses on validation and verification of hydrogen peroxide fumigation while considering the entire fumigation process. The two parts together will serve users as a guide to establishing hydrogen peroxide fumigations at their facilities.

Assessment of Electromagnetic Pollution in Some Hospitals and Schools in Al-Najaf City

The tremendous benefits of using cellular phones, which began to increase and unprecedented spread worldwide last decade, were accompanied by harmful effects on the environment due to the increase in electromagnetic radiation (EMR) which be emitted from mobile phone towers. This effect on humans, animals, and plants, which is considered a form of environmental pollution, was sensed by developed countries and Environmental protection organizations. These countries have established restrictions and enacted laws to reduce their negative impact on living beings. The field survey included six major hospitals and 38 schools were distributed over the central neighbourhoods in Al-Najaf city. The results showed that power density (PD) measurements for 4 out of 6 hospitals and 27 out of 38 schools were higher than the biological limit (BL) adopted in this article. This limit is considered as an indicator of the onset of a harmful effect on brain and body tissues. The highest value for PD in hospitals was 5.62 mW/m2 recorded in Al-Sadr Teaching Hospital. PD measurements ranged from1.33 from 3.92 mW/m2 in the selected schools where its readings exceeded the BL. When comparing the PD measurements at the selected sites with limits set by the "International Commission on Non-Ionizing Radiation Protection (ICNIRP)" they were less than the recommended limit in those specifications. All values of specific absorption rates (SAR) in W/Kg were below the ICNIRP Guidelines' limit. However, they were above the biological limit for four hospitals and several of the selected schools.

Lead contamination among Paris Fire Brigade firefighters who fought the Notre Dame Cathedral fire in Paris.

On 15th April 2019, the fire at Notre Dame Cathedral, Paris, resulted in the melting of 410 tons of lead. Four hundred fourteen Paris firefighters were involved. For the purpose of preventive medicine, the level of lead contamination among the firefighters was assessed. This study objectives' were to describe the blood lead levels (BLLs) in the firefighters, to study the influence of some parameters such as the function of firefighters and the decrease in BLLs during the follow-up investigations. The emission of 138kg of melted lead from the roof and spire of the Notre Dame Cathedral during the fire was estimated by the National Institute for Industrial Environment and Risks. Three categories were defined according to the estimated levels of external lead exposure and fire proximity: high (category 1, n=170), medium (category 2, n=151), and low (category 3, n=93). Two to three weeks after the fire, blood samples to assess the BLLs were taken from firefighters in category 1 (N=164) and from every female firefighter in category 1 and 2 (N=4). When the BLL was above 50μg/L (95th percentile of reference range concentrations for a sample of the French population), it was checked again at one month later (N=31) and then, if still above 50μg/L, at six months later (N=10). The geometric mean of initial blood lead level was 31.5μg/L (CI 95% [27.7-35.9]; Min-Max: 7.0-307.6μg/L). Twenty-five percent (n=42) of initial BLLs were above 50μg/L, versus 10% (n=16) at 1 month, and 2% (n=3) at 6 months. The French binding biological BLL limit value (400μg/L for men and 300μg/L for women was never exceeded and all BLLs decreased over time. BLLs varied according to the function occupied during the extinguishing of the fire: operators', officers' and those of unknown function. BLLs were significantly higher compared to drivers reflecting their lower distance to fire and fume. The fire at Notre Dame Cathedral, Paris, resulted in moderate lead contamination among firefighters. Individual and collective protection measures probably helped to limit the contamination. Nevertheless, an effort could be made to improve the working conditions by rethinking the respiratory protection.

Factors Influencing the Sex Ratio at Birth in India: A New Analysis based on Births Occurring between 2005 and 2016.

Previous research on sex ratio at birth (SRB) in India has largely relied on macro‐analysis of census data that do not contain the breadth of factors needed to explain patterns in SRB. Additionally, no previous research has examined the differentiation of factors associated with SRB across birth orders, a key determinant in societies affected by son preference. This study aims to fill these gaps using micro‐data related to 553,461 births occurring between 2005 and 2016 collected as part of the 2015–2016 National Family Health Survey. Analyses used multivariable logistic regressions stratified by birth order to examine associations with SRB at the national level. The SRB at birth order 1 was outside the biological normal limit, and generally increased with birth order. First births in households with wealth in the middle and richest quintiles, with mothers who desired a higher ideal number of sons than daughters, and in lower fertility communities had a higher probability of being male. Most SRB correlates were visible at birth orders 3 or higher. Programs and policies designed to address India's male‐skewed SRB must consider the diverse factors that influence SRB, particularly for higher order births.

Is Urinary Chromium Specific to Hexavalent Chromium Exposure in the Presence of Co-exposure to Other Chromium Compounds? A Biomonitoring Study in the Electroplating Industry.

Electroplating processes are widely used in metal industries to improve the resistance properties of manufactured metal parts. Workers in this industry are potentially exposed both to hexavalent chromium (Cr(VI)) and to other chromium compounds [mostly trivalent chromium (Cr(III))], due to the use of chromic acid baths. The goal of this study was to validate urinary chromium as a Cr(VI) exposure biomarker in the presence of exposure to other chromium compounds. A biomonitoring study consisted in monitoring airborne chromium exposure and urinary chromium for one working week in 93 workers from nine electroplating companies. Chromium concentrations were measured in all urinations of each volunteer for the working week. Individual airborne soluble and insoluble Cr(VI) as well as Cr(III) concentrations were measured for all of the shifts of the week. The main statistical analysis consisted in modelling, in a Bayesian framework, the pre- and post-shift urinary chromium as a function of airborne Cr(III) and airborne Cr(VI), taking into account the day of the week and the time of collection of the urines (pre- or post-shift). Preliminary descriptions showed an increase in pre-shift urinary chromium during the working week. The model showed an increase in urinary chromium over the shift related to the shift-specific airborne Cr(VI) concentration as well as an increasing trend over the week and a relationship with the mean weekly Cr(VI) thought to reflect chronic exposure. Taking into account the Cr(VI) exposure, there was no evidence of an effect of Cr(III) exposure on urinary chromium. A biological limit value (BLV) was derived from the French occupational exposure limit for Cr(VI) of 1 µg m-3 and was estimated at between 1.9 and 2.6 µg g-1 creatinine for a urinary sample collected at the end of the shift on the last working day of the week. In the present context of mixed exposure to Cr(III) and Cr(VI) in electroplating, this study showed that urinary chromium depended only on airborne Cr(VI) concentrations, which justifies using a BLV for assessing workers' exposure. The estimated BLV was close to the recommended French BLV, which is 1.8 µg g-1 creatinine, in the electroplating industry.

Frequency following responses and rate change complexes in cochlear implant users

The upper limit of rate-based pitch perception and rate discrimination can differ substantially across cochlear implant (CI) users. One potential reason for this difference is the presence of a biological limitation on temporal encoding in the electrically-stimulated auditory pathway, which can be inherent to the electrical stimulation itself and/or to the degenerative processes associated with hearing loss. Electrophysiological measures, like the electrically-evoked frequency following response (eFFR) and auditory change complex (eACC), could potentially provide valuable insights in the temporal processing limitations at the level of the brainstem and cortex in the electrically-stimulated auditory pathway. Obtaining these neural responses, free from stimulation artifacts, is challenging, especially when the neural response is phase-locked to the stimulation rate, as is the case for the eFFR. In this study we investigated the feasibility of measuring eFFRs, free from stimulation artifacts, to stimulation rates ranging from 94 to 196 pulses per second (pps) and eACCs to pulse rate changes ranging from 36 to 108%, when stimulating in a monopolar configuration. A high-sampling rate EEG system was used to measure the electrophysiological responses in five CI users, and linear interpolation was applied to remove the stimulation artifacts from the EEG. With this approach, we were able to measure eFFRs for pulse rates up to 162 pps and eACCs to the different rate changes. Our results show that it is feasible to measure electrophysiological responses, free from stimulation artifacts, that could potentially be used as neural correlates for rate and pitch processing in CI users.

Prostorne modulacije i dezeni materija •

In this paper, János Sziveri’s poetry is studied from the perspective of associative plays based on matter-grouping and landscape visions. There was a productive correspondence, as the poet himself underlined it, between him and Vasko Popa’s works. The consonance between the book plans and the cycles of poems by Vasko Popa dedicated to the decom- position and recomposition of different matters and remains and the series of Sziveri’s texts are secured by the stock of biological limitations and tactile sensations. The processes of focusing on different bodies and moving from body to body and the excess of neuro- transmission as well as the desire for gratification are most efficiently distributed by the singular or plural first person. The Vasko Popa-esque radiation of life conditions extending beyond instrumentalized functioning and existence based on imitation echoes in Sziveri’s landscape descriptions by intensifying the creative potential of fixed stance and mobility.The antipoetics and the cyclical planning of the texts of the Serbian author with some Ro- manian ancestors in his family tree were properly cultivated and elevated by his Hungarian- speaking companion.Francis Ponge’s art can be considered as their literary precursor. Almost anything that can be told about water, fauna, flora, and the natural cycle, about the sea, shells, snails, pebbles, bones, and oranges, is told in Le parti pris des choses (1942), Ponge’s prose-poem cycle, which prevailed in the works of the well-informed Vasko Popa and, through Popa, in Sziveri’s texts as well.Sziveri’s criticism of targeting the patterns of social viability of South-Eastern Euro- pean repressive practices and collective false consciousness drowning in platitudes is ac- companied by topographic scenery and ethnic diversity which accumulated landscape sur- faces, fragments, and neighbourhoods framed by the Danube, Tisza, and Bega rivers as the scenes of geospecific identity. Comparing existential calculations, describing the shrinking of an ill body – these can be considered as a perceptual Pannonism of a subject observing and recording its direct impressions precisely and accurately.Clinging onto the love of life, self-defence supplied by background knowledge about the countryside – as if all these were representing the escapist way of hiding, disguise, and diversion. Being doomed to live as an outcast, as a result of the status quo of regional co- existence officially prescribing homogeneity and of institutionalized incitement of feud, seems to be a dead certain conditioning of life. His attitude against any kind of quailing, his manner of shrugging off or making fun of regional fixed ideas and minority melodramas, bodily and linguistic ‘Babylonization’ coalesce into a polyphonic credo of a poet standing in the shade of wrecking and falling apart.

Autoimmune and Chronic Inflammatory Disease Patients with COVID-19.

ObjectiveThere are limited data on the impact of coronavirus disease 2019 (COVID‐19) on hospitalized patients with autoimmune and chronic inflammatory disease (AICID) compared with patients who do not have AICID. We sought to evaluate whether patients with AICID who have confirmed COVID‐19 presenting to the hospital are at higher risk of adverse outcomes compared with those patients without AICID who are infected with COVID‐19 and whether immunosuppressive medications impact this risk.MethodsWe performed a multicenter retrospective cohort study with patients presenting to five hospitals in a large academic health system with polymerase chain reaction–confirmed COVID‐19 infection. We evaluated the impact of having an AICID and class of immunosuppressive medication being used to treat patients with AICID (biologics, nonbiologic immunosuppressives, or systemic corticosteroids) on the risk of developing severe COVID‐19 defined as requiring mechanical ventilation (MV) and/or death.ResultsA total of 6792 patients with confirmed COVID‐19 were included in the study, with 159 (2.3%) having at least one AICID. On multivariable analysis, AICIDs were not significantly associated with severe COVID‐19 (adjusted odds ratio [aOR] 1.3, 95% confidence interval [CI]: 0.9‐1.8). Among patients with AICID, use of biologics or nonbiologic immunosuppressives did not increase the risk of severe COVID‐19. In contrast, systemic corticosteroid use was significantly associated with an increased risk of severe COVID‐19 (aOR 6.8, 95% CI: 2.5‐18.4).ConclusionPatients with AICID are not at increased risk of severe COVID‐19 with the exception of those on corticosteroids. These data suggest that patients with AICID should continue on biologic and nonbiologic immunosuppression but limit steroids during the COVID‐19 pandemic.

Surrogacy, uterus transplantation and artificial uterus: approaches from the biolaw

More than forty years after the first baby's birth through in vitro fertilization, innovations in the field of human reproduction have experienced a significant growth increase. Those first techniques have led evolved to others that push the biological limits of reproduction. Recent developments in genomic editing -particularly, CRISPR/Cas9 technology- had leaded an intense ethical, social and legal discussion about the boundaries limits of the new models of human reproduction, and their consequences in recent years. The number of conflicting legal interests suggests that the application of these techniques must combine the respect for the law, the defense of the human rights of all the agents involved in the process, and the freedom of scientific research. The present paper tries to deal with the diverse ethical implications and legal limits of three of those techniques, recently developed or to be developed in the near future: surrogacy, uterus transplantation and artificial uterus.

Inferring mechanisms of response prioritization on social media under information overload

Human decision-making is subject to the biological limits of cognition. The fluidity of information propagation over online social media often leads users to experience information overload. This in turn affects which information received by users are processed and gain a response to, imposing constraints on volumes of, and participation in, information cascades. In this study, we investigate properties contributing to the visibility of online social media notifications by highly active users experiencing information overload via cross-platform social influence. We analyze simulations of a coupled agent-based model of information overload and the multi-action cascade model of conversation with evolutionary model discovery. Evolutionary model discovery automates mechanistic inference on agent-based models by enabling random forest importance analysis on genetically programmed agent-based model rules. The mechanisms of information overload have shown to contribute to a multitude of global properties of online information cascades. We investigate nine characteristics of online messages that may contribute to the prioritization of messages for response. Our results indicate that recency had the largest contribution to message visibility, with individuals prioritizing more recent notifications. Global popularity of the conversation originator had the second highest contribution, and reduced message visibility. Messages that presented opportunity for novel user interaction, yet high reciprocity showed to have relatively moderate contribution to message visibility. Finally, insights from the evolutionary model discovery results helped inform response prioritization rules, which improved the robustness and accuracy of the model of information overload.

Status and Exploitation of 74 Un-Assessed Demersal Fish and Invertebrate Stocks in the Aegean Sea (Greece) Using Abundance and Resilience

Stocks with low market value are rarely included in stock assessments because their catch records are generally lacking, thus adding to the already large number of un-assessed fisheries at a global scale. T his deficiency is more evident in the Mediterranean Sea where stock assessments are relatively fewer. A new method (AMSY) has been recently developed to assess stocks for which only abundance trends from scientific surveys are available. The AMSY method was used in the Aegean Sea to assess the status of 74 fish and invertebrate stocks (50 actinopterygians, 4 sharks, 5 rays, 12 cephalopods, and 3 crustaceans) for which catch data are lacking; 20 of them have medium or high market value and are being targeted by fishing fleets, while the remaining 54 are either not targeted, but by-caught and often discarded, or are not exploited at all. Overall, 31 of the 54 non-targeted stocks (57%) were healthy in terms of biomass (B/Bmsy > 1), whereas only 6 of the 20 targeted stocks (30%) were healthy. Of the 23 unhealthy non-targeted stocks, 12 were near healthy (B/Bmsy > 0.75), compared to only 1 of the targeted stocks, whereas 10 non-targeted stocks (19%) and 10 targeted ones (50%) were outside safe biological limits (B < 0.5Bmsy). Cephalopods and crustaceans were generally in a better status compared to fishes. The results confirm that fishing does not only affect commercial stocks, but it may also affect by-catch stocks. In general, stocks that are targeted by fishing fleets are in a worse status in terms of biomass compared to those that are only occasionally collected as by-catch or those that inhabit environments that are not accessible to fishing fleets.

Estimations of benchmark dose for urinary metabolites of coke oven emissions among workers.

Coke oven emissions (COEs), usually composed of polycyclic aromatic hydrocarbons (PAHs) and so on, may alter the relative telomere length of exposed workers and have been linked with adverse health events. However, the relevant biological exposure limits of COEs exposure has not been evaluated from telomere damage. The purpose of this study is to estimate benchmark dose (BMD) of urinary PAHs metabolites from COEs exposure based on telomere damage with RTL as a biomarker. A total of 544 exposed workers and 238 controls were recruited for participation. High-performance liquid chromatography and qPCR were used to detect concentrations of urinary mono-hydroxylated PAHs and relative telomere length in peripheral blood leukocytes for all subjects. The benchmark dose approach was used to estimate benchmark dose (BMD) and its lower 95% confidence limit (BMDL) of urinary OH-PAHs of COEs exposure based on telomere damage. Our results showed that telomere length in the exposure group (0.75 (0.51, 1.08)) was shorter than that in the control group (1.05 (0.76,1.44))(P<0.05), and a dose-response relationship was shown between telomere damage and both 1-hydroxypyrene and 3-hydroxyphenanthrene in urine. The BMDL of urinary 1-hydroxypyrene from the optimal model for telomere damage was 1.96, 0.40, and 1.01 (μmol/mol creatinine) for the total, males, and females group, respectively. For 3-hydroxyphenanthrene, the BMDL was 0.94, 0.33, and 0.49 (μmol/mol creatinine) for the total, males, and females. These results contribute to our understanding of telomere damage induced by COEs exposure and provide a reference for setting potential biological exposure limits.

Optimal Local Estimates of Visual Motion in a Natural Environment.

Many organisms use visual signals to estimate motion, and these estimates typically are biased. Here, we ask whether these biases may reflect physical rather than biological limitations. Using a camera-gyroscope system, we sample the joint distribution of images and rotational motions in a natural environment, and from this distribution we construct the optimal estimator of velocity based on local image intensities. Over most of the natural dynamic range, this estimator exhibits the biases observed in neural and behavioral responses. Thus, imputed errors in sensory processing may represent an optimal response to the physical signals sampled from the environment.

Alexa, Dio esiste? Robotica, intelligenza artificiale e fenomeno religioso: profili giuridici

Drawn from ontotheological issues explored in a prescient science fiction novel from the 1980s, this paper speculates about the potential relations and contributions of artificial intelligence to theology and religious practice, together with the legal regimes that might govern them. It concludes that no exploration of the human implications of robotics can ignore the resources of religion and belief in debates about the ethical issues robotics raises; the relation between religion and robotics is relevant to questions about «transhumanism» – the possibility of overcoming the intellectual, biological, and physical limitations of human beings through their use of robotics and artificial intelligence; and incredible as it might seem, one cannot ignore the possibility that robotics and artificial intelligence will uncover the means of developing or evolving a kind of spirituality within machines, with profound implications for religion and law

Human biomonitoring initiative (HBM4EU): Human biomonitoring guidance values (HBM-GVs) derived for cadmium and its compounds

AimsThe methodology agreed within the framework of the HBM4EU project is used in this work to derive HBM-GVs for the general population (HBM-GVGenPop) and for workers (HBM-GVWorker) exposed to cadmium (Cd) and its compounds. MethodsFor Cd, a significant number of epidemiological studies with dose–response relationships are available, in particular for kidney effects. These effects are described in terms of a relation between urinary Cd (U-Cd) or blood Cd (B-Cd) levels and low molecular weight proteinuria (LMWP) markers like beta-2-microglobulin (β2M) and retinol-binding protein (RBP). In order to derive HBM-GVs for the general population and workers, an assessment of data from evaluations conducted by national or international organisations was undertaken. In this work, it appeared relevant to select renal effects as the critical effect for the both groups, however, differences between general population (including sensitive people) and workers (considered as an homogenous population of adults who should not be exposed to Cd if they suffer from renal diseases) required the selection of different key studies (i.e. conducted in general population for HBM-GVGenPop and at workplace for HBM-GVWorker). Results and conclusionsFor U-Cd, a HBM-GVGenPop of 1 µg/g creatinine (creat) is recommended for adults older than 50 years, based on a robust meta-analysis performed by EFSA (EFSA, 2009a). To take into account the accumulation of Cd in the human body throughout life, threshold or ‘alert’ values according to age were estimated for U-Cd. At workplace, a HBM-GVWorker of 2 μg/g creat is derived from the study of Chaumont et al., (2011) for U-Cd, and in addition to this recommendation a HBM-GVworker for B-Cd of 5 µg/L is also proposed. The HBM-GVWorker for U-Cd is similar to the biological limit value (BLV) set by the new amendment of the European Carcinogens and Mutagens Directive in June 2019 (2 µg/g creat for U-Cd).

Retention and relapse: An anamnesis

The problem of retention and relapse was born with the science of orthodontics and continues to persistently disturb Orthodontic researchers and clinicians. In spite of all the advances in the active treatment procedures, retention and relapse remains a problem for many practitioners. Several studies have been carried out to determine the changes taking place several years after orthodontic treatment and the influencing factors. Factors including growth, periodontium, age, third molars, tooth dimensions etc., have been held responsible for post treatment relapse. Several procedures have been devised to ensure stability and prevent or at least avoid post treatment changes so as to reduce relapse. To achieve this purpose, a proper understanding of the changes occurring, various factors affecting relapse and retention procedures is important. Thus problems of retention and the continued trend, which owes to the biological and mechanical limitations, demands to go through the state of art of this perennial problem “Retention and Relapse”. Keywords: Retention, Relapse, Orthodontics.