We studied occupational exposure to phthalates from first-morning-void urine sample of hairdressing apprentices by HPLC-MS/MS analyses and association with health status. Metabolites of mono(2-ethyl-5-hydroxyhexyl) phthalate (MEHHP), mono ethyl phthalate (MEP), mono- n-butyl phthalate (MnBP) and mono-iso-butyl phthalate (MiBP) were detected in all urine samples, followed by metabolites mono(2-ethyl-5-oxohexyl) phthalate (MEOHP) and mono(2-etylhexyl) phthalate (MEHP) occurring in 97.06% and 86.76% of samples, respectively. Positive associations for females were observed between MnBP and fat-free mass index (FFMI) and age; negative associations were found between MEHP, MEOHP, MEHHP, sum of MEHP, MEHHP, MEOHP and vital capacity and also between MEHP and forced vital capacity (FVC of predicted value (PV)). Lengths of exposure were associated to MnBP, MEHHP, and MEP. We also documented positive associations between anthropometry (body mass index, waist-to-height ratio (WHtR), FFMI, fat mass index) and pulmonary function FVC% of PV for females and negative associations between WHtR, waist-to-hip ratio, FFMI and ratio of forced expiratory volume in 1 s (FEV₁) to FVC (FEV₁/FVC). We assume that factors of occupational environment of hairdressing apprentices are affected by phthalates and resulted in negative outcomes in breathing mechanism and influence of body composition. Adipose tissue could play role as confounding factor in urine excretion of phthalates because of their lipid solubility and accumulation.

Plants have a potential for the uptake and accumulation of essential and non-essential trace elements. The ability to take up and tolerate metals varies between and within species as well as between metals. For most metals, the mechanisms involved in plant tolerance, uptake and accumulation are still not fully known and it is not known to what extent the plant response is metal-specific rather than a general stress response. In the present study, the growth response of soybean to Cd, As, Al and NaCl was compared and contrasted to simple sequence repeat (SSR) marker analysis results for Cda1, a dominant gene located in a major quantitative trait locus that regulates Cd accumulation in soybean, to evaluate the hypothesis that general effect patterns are induced by the individual metals. Principal component analysis revealed that the root growth response was most diverse for Al exposure and decreased in the order of Al > As > Cd > NaCl. NaCl did not exert a differentiating effect, indicating response mechanisms similar, at least partially, to metal exposure. The applied stressors yielded a distinguishable pattern of root responses, indicating the potential of such screens to identify agents acting similarly or differently. The SSR marker analysis also facilitated characterization of the Cd accumulation potential of the 22 soybean cultivars studied, and thereby identification of cultivars with potential health risk under cultivation in Cd-contaminated soils.

Arsenic is a serious soil pollutant with toxic effects on biological systems. Elevated soil concentrations may negatively affect crop production and food safety. The impact of arsenic on plants depends on many factors, including nitrogen availability. Nitrogen (N) as an essential mineral affects overall energetics of plants, while its non-optimal doses have been shown to also impact plant performance and yield, as well as tolerance to environmental constraints. The combined effects of these two factors, however, have been rarely studied. Here we investigated the impact of sublethal doses of As³⁺ (5 mM) on wheat plants grown in hydropony, applying a set of 8 different N concentrations spanning from starvation (0 mM N in the media) through optimum (7.5 mM N) to excessive amounts (up to 35 mM N). The results showed that the content of photosynthetic pigments varies depending on N concentration and As³⁺ presence. The different energetic status of plants also affected the final As uptake. Establishing nutrition conditions might be important for limiting metal(loid) uptake from soil in contaminated areas.

Graphs can be considered as useful mathematical models. Graph algorithms are a common part of undergraduate courses in discrete mathematics. Even though they have been successfully implemented in secondary curricula, little research has been dedicated to the analysis of students’ work. Within a discrete mathematics course for university students, several graph algorithms were introduced via their applications. At the end of the course, the students took a test focused, inter alia, on applications of the algorithms. The mistakes that occurred in 127 students’ solutions of three problems (the Chinese postman problem, the shortest path problem, and the minimum spanning tree problem) were categorized and compared. Surprisingly, no mistakes were identified in the mathematization of situations or in the interpretation of results with respect to the wording of the problem. The categories of errors varied regardless of the problem types. Hierarchical cluster analysis grouped together the students’ solutions for the Chinese postman problem and the minimum spanning tree problem. By means of nonparametric item response theory analysis, the Chinese postman problem was identified as the most problematic for students. Possible sources of this difficulty are discussed in more detail herein.