Blood lead concentrations in children with iron deficiency anemia: a systematic review and meta-analysis

Iron deficiency is the most common nutritional disorder detrimental to the behavior, cognitive performance, immune system, and physical growth of infants and preschool- and school-age children. Iron deficiency anemia (IDA) increases children's susceptibility to some metals, including the highly toxic lead (Pb), but the character of this relationship is still disputed. Thus, this study aimed to review and meta-analyze the association between the IDA and blood lead levels (BLL) among children, based on papers indexed by international scientific databases and published up to September 2021. A search was performed of the literature in several databases including the ISI Web of Science, PubMed, and Scopus. The final papers were assessed concerning their quality based on the Newcastle-Ottawa Scale (NOS) for cross-sectional studies. Moreover, analyses were performed using R statistical software with the "meta" package. Of the 1528 articles found, only 12 studies met the inclusion criteria and were considered in the meta-analysis. Significantly higher BLL in IDA children (SMD = 2.40; CI 95%, 0.93-3.87 µg/L; p = 0.0014) was seen when compared to non-IDA children. Moreover, the pooled OR is equal to 2.75 (CI 95%, 1.10-6.85 µg/L; p = 0.0303) suggesting a higher risk of IDA development among children with BLL > 10 µg/dL. Thus, we recommend systematic monitoring of Fe and Pb levels among children, especially in countries with limited sources of nutritious food. Since only a few studies were available for this meta-analysis, further studies are necessary to examine the association between IDA and BLL in detail.

Relationship between gestational diabetes and serum trace element levels in pregnant women from Eastern Iran: a multivariate approach

The prevalence of gestational diabetes mellitus (GDM) has increased over the recent decades. Exposure to environmental contaminants may be a risk factor for the development of GDM, but this is heavily dependent on particular circumstances. Studies on various areas linking various factors are therefore needed. We examined the associations between serum trace element levels and incidents of GDM among 102 pregnant women (diabetic n = 60 and healthy n = 42) living in Birjand (Iran). Blood serum samples were analyzed for concentrations of elements linked to particulate matter air pollution such as As, Cd, Cu, Hg, Mn, Ni, V, and Zn. Concentrations of As (8.58 vs. 3.15 μg/L), Cd (6.74 vs. 0.52 μg/L), and Hg (2.60 vs. 0.90 μg/L) were significantly higher in women with GDM. Risk difference (RD) estimation showed that As, 0.516 (0.355, 0.677); Cd, 0.719 (0.534, 0.904); and Hg, 0.505 (0.276, 0.735) increase GDM probability, while V lower that risk, -0.139 (-0.237, -0.042). With the principal component analysis, we were able to separate subjects according to their GDM status based on element levels. Such classification revealed very high efficiency with a true positive rate of 93%, according to linear discriminant analysis. GDM subjects presented higher levels of As, Cd, and Hg, indicating that these elements may disturb insulin metabolism and promote the development of GDM. Therefore, we conclude that systematic monitoring of trace elements followed by multivariate modeling in women planning pregnancy should be carried out to prevent the development of GDM.

Metal Risk Assessment Study of Canned Fish Available on the Iranian Market

Iran is the largest fishery producer in the region reaching nearly 1 million tons. Fish provide a good many nutrients that are beneficial for our health. Due to significant deposits of xenobiotics in the water environments, however, fish may also be a source of non-essential metals, causing a variety of disorders. The main challenges to Iranian fisheries are environmental pollution and quality control, so this study aims to estimate the concentration of cadmium (Cd), mercury (Hg), nickel (Ni), and lead (Pb) in canned tuna fish produced and consumed in Iran. We studied four popular brands (N = 4 × 20) with ICP-MS and then looked at the concentrations and calculated the risk assessment parameters. We found that the lowest concentration was observed for Cd (18 μg/kg) and the highest for Ni (132 μg/kg). Among the brands studied, Pb concentrations differed most (42.0 to 113.3 μg/kg) and Hg levels were more consistent (24.0 and 39.4 μg/kg). The concentrations of Cd, Hg, and Pb in all the brands tested were below EU permissible thresholds. The intake estimation risk assessment parameters (EDI, contribution to PTWI, and CR) and non-cancer risk assessment parameters based on reference doses (THQ and HI) demonstrated the safety of tested products in respect to all metal concentrations studied, while the parameters regarding the toxic effects (MoE, and ILCR) showed that the consumption might cause health risks in terms of Cd (ILCR), Ni (ILCR), and Pb (MoE). The consumption of the canned fish studied should therefore be maintained at a reasonable level (2-5 meals containing fish weekly), so that it may provide necessary nutrients, while avoiding the health risk due to metal content.

Foraging ecology drives mercury contamination in chick gulls from the English Channel

Although mercury (Hg) occurs naturally, human activity is currently the greatest source of release and the ocean receives Hg inputs by rivers and atmospheric deposition. Seabirds including chicks serve as valuable bioindicators of Hg contamination, reflecting local contamination around the colony. This study investigates the ecological drivers (trophic position and foraging habitat) influencing Hg concentrations in blood and feathers of chicks of three sympatric marine gull species. Chicks were sampled between 2015 and 2017 in the Seine Estuary, one of the most Hg contaminated rivers in Europe, and in the Normand-Breton Gulf (the Chausey Islands), 200 km west, as a reference site with limited contaminant inputs. The trophic status of the chicks was evaluated based on the relative abundance of stable isotopes (δ¹³C, δ¹⁵N and δ³⁴S). There was a tight correlation between Hg concentrations, as well as the abundance of stable isotopes, in blood and feathers. Great black-backed gull had the highest blood Hg concentrations of the species (1.80 ± 0.92 μg⋅g^-1 dry weight (dw)); the Lesser black-backed gull had intermediate concentrations (0.61 ± 0.18 μg⋅g^-1 dw); and the European herring gull had the lowest (0.37 ± 0.26 μg⋅g^-1 dw). Individuals with the highest trophic position showed consistently the highest Hg concentrations. The positive relationship between Hg concentrations and the feeding habitat (marine vs terrestrial) indicated that the main source of Hg for gulls in the English Channel is marine prey. This exposure led to relatively high Hg concentrations in Great black-backed gull, which may produce toxic effects to individuals with potential consequences for their populations.

Essential and xenobiotic elements in cottage cheese from the Slovak market with a consumer risk assessment

The examination of various elements in the milk products is very important in the food sector in respect of food quality and safety. The aim of this study was to determine the concentrations of calcium (Ca), cobalt (Co), cadmium (Cd), copper (Cu), chromium (Cr), iron (Fe), mercury (Hg), potassium (K), magnesium (Mg), sodium (Na), nickel (Ni), phosphorus (P), lead (Pb) and zinc (Zn) in white cottage cheese or cottage cheese supplemented with various additives (white, lacto-free, chive, tzatziki, mustard + onion, chili, active protein) available on the market of Slovakia. All essential elements were within the reference range. Cottage cheese enriched with tzatziki showed higher amount of Cu, Fe, K, and Zn. Mustard + onion cheese contained high values of Ca, Co, Mg, and Ni. In white cottage cheese high amount of Cr, Mn, and P was measured. The content of xenobiotic metals was below permitted limit. The contribution to PTWI (Provisional tolerable weekly intake) suggested very low dietary exposure to heavy metals as Cd, Hg, and Pb as well as other metals (Cu, Ni, and Zn) in cottage cheese. Numerous correlations between concentrations were observed. MOE (Margin of Exposure) evaluation denoted that average consumption of cottage cheese does not pose any high cardiovascular and nephrotoxicity threat.

Urinary Metal Levels with Relation to Age, Occupation, and Smoking Habits of Male Inhabitants of Eastern Iran

In low-income and middle-income countries such as Iran, smoking is becoming increasingly popular, especially among young people. This has led to additional exposure to a variety of substances, including metals which may exert a toxic influence and lead to severe diseases. In order to evaluate the influence of smoking on metal concentrations, a case-control study of levels of metal in urine was carried out in smokers (n = 64) and non-smokers (n = 35) from the city of Birjand (Iran). They were divided according to their age and socioeconomic status. Concentrations of cadmium (Cd), cobalt (Co), chromium (Cr), copper (Cu), iron (Fe), nickel (Ni), lead (Pb), and zinc (Zn) were measured using ET-AAS. We found higher concentrations of Cd (0.03 vs. 0.12 μg/L), Co (0.6 vs. 1.22 μg/L), and Cr (14.00 vs. 18.17 μg/L) in the urine of smokers. Age and occupation are factors that also influence the levels of metals. Young smokers demonstrate higher Cd and Pb levels than other age groups. It would also appear that public sector workers and self-employed are the sectors most susceptible to high levels of metals.

Cadmium and chromium levels in water and edible herbs in a risk assessment study of rural residents living in Eastern Iran

In arid and semi-arid regions of Iran, water is supplied by qanats, underground channels where pollution is suspected, but unestablished. The aim of this study was thus to run a risk assessment study regarding the levels of cadmium (Cd) and chromium (Cr) in qanat water and edible herbs (Adiantum capillus-verenis, Chara globularis and Plantago lanceolata) growing in qanats in 14 villages in South Khorasan Province in Iran between April and August 2018. Samples were collected in qanats from the same sampling points, and after mineralization in nitric and perchloric acids were analyzed for metal concentrations by means of atomic absorption spectrometry. Concentrations of Cd and Cr found in water were not high (0.028 and 1.091 μg L^-1, respectively) and contamination parameters revealed no pollution. The ingestion rate of water and the exposure frequency to metals were the most relevant variables in the model of a sensitivity analysis, but the Hazard Quotient indicated no risk of non-carcinogenic health problems to consumers of the water. The Carcinogenic Risk parameter suggested, however, that there is a risk of these consumers' developing cancer. Concentrations found in herbs were higher than in water but remained below permissible thresholds. Hazard Quotient values of three species studied in the case of children and A. capillus-verenis in the case of adults indicated a potential non-carcinogenic health risk linked with eating them. The study reveals that further research to include many of the qanats across Iran should be carried out to verify the scale of the risk suggested. Graphical abstract.

Levels of Essential and Xenobiotic Elements and Their Relationships in Milk Available on the Slovak Market with the Estimation of Consumer Exposure

The monitoring of various elements in the cow milk is important in the agricultural sector. The goal of this study was to determine the concentrations of calcium (Ca), cadmium (Cd), copper (Cu), iron (Fe), mercury (Hg), potassium (K), magnesium (Mg), sodium (Na), nickel (Ni), lead (Pb), and zinc (Zn) in the milk samples coming from different origins (local region in Nitra, nationwide sample represents the common Slovak brands of milk and common brands of milk from Czech Republic widely available in Slovakia). The samples were analyzed using atomic absorption spectrometry. A high level of variability in the Cu, Fe, Na, Ni, and Zn contents was observed. Magnesium was comparatively high in the milk sample from Slovakia (273.23 ± 16.32 μg/mL) against sample from Nitra (230.91 ± 9.48 μg/mL) and Czech Republic (202.70 ± 10.83 μg/mL). Potassium was significantly higher in milk from Nitra region (3301.98 ± 95.66) against SK sample (2925.16 ± 75.74 μg/mL). There were no significant differences in other elements among the three regions. The provisional tolerable weekly intake (PTWI) contribution suggested low dietary exposure to observed toxic metals (Cd, Hg, and Pb) in milk samples. Margin of exposure (MOE) evaluation denoted that even higher consumption of milk poses no high cardiovascular and nephrotoxicity threat. However, Cd and Pb are known for their cumulative effect and the monitoring of these elements in milk is strongly required.

Metal Concentrations in Tissues of Gadwall and Common Teal from Miankaleh and Gomishan International Wetlands, Iran

Miankaleh and Gomishan International Wetlands are important wintering areas for waterbirds in the Caspian Sea region. Previous studies revealed increased exposure to metals in some species of waterbirds using these wetlands. In this study, we examined concentrations of cadmium (Cd), chromium (Cr), iron (Fe), lead (Pb), and zinc (Zn) in kidneys, liver, and pectoral muscle of wintering Gadwall (Anas strepera) and Common Teal (Anas crecca) collected in 2012. In addition, we measured concentrations of these elements in water and sediments from the collection sites. The genders differed in only one element/tissue combination, i.e., concentrations of Fe were greater in the livers of males. Concentrations of elements observed in Gadwall were generally higher than in Common Teal; only renal Cr and muscle Zn did not differ between species. Mean Cd concentrations in Gadwall exceeded background levels, reaching 1.94 μg/g ww in kidneys and 1.09 μg/g ww in liver. Similarly, Pb concentrations in Gadwall were also elevated (4.14 μg/g ww in kidneys, 3.22 μg/g ww in liver). Concentrations of other metals were within ranges commonly found in waterfowl. Concentrations of elements in the environment were elevated above background and comparable with the data obtained for this region by other scientists. However, these levels were deemed to not be great enough to pose an acute health risk to waterfowl. Given increased concentrations of some metals in duck tissues, further inquiry into the source of the exposure is needed for this area.

Levels of metals in blood samples from Mallards (Anas platyrhynchos) from urban areas in Poland

In this paper we present the studies conducted on blood samples taken from Mallards (Anas platyrhynchos). Birds were captured for ringing purposes (n = 43) in two small and two big towns (including highly urbanized areas). For comparison samples of blood from birds shot on fish ponds were used (n = 26). Based on the body mass all sampled individuals can be assessed as being in good condition. Levels of cadmium (Cd), chromium (Cr), copper (Cu), iron (Fe), nickel (Ni), lead (Pb) and zinc (Zn) in blood samples were measured with AAS. Concentrations of metals did not differ statistically between sexes and made up a following order: Fe > Zn > Cu > Cr ≈ Ni > Pb > Cd. Mallards from towns revealed lower concentrations of Zn and Cu but higher concentration of Fe. There was no difference in exposition to Pb between birds from towns and fish ponds.