In Iraq, war contamination is the result of dispensed bombs, bullets, detonation of chemical and conventional weapons, and burn-pit emissions by US bases. Increases in congenital anomalies were reported from Iraqi cities post-2003. These cities were heavily bombed and encircled by US bases with burn-pits. Thorium is a radioactive compound and a direct depleted-uranium decay-product. Radioactive materials, including depleted uranium, are routinely stored in US bases and they have been shown to leak into the environment. We conducted a case-control study to investigate associations of residential proximity to Tallil Air Base, a US military base near Nasiriyah, as well as levels of uranium and thorium in hair and deciduous teeth with congenital anomalies. The study was based on a sample of 19 cases and 10 controls who were recruited during late Summer and early Fall of 2016. We developed mixed effects logistic regression models with village as the random effect, congenital anomaly as the outcome and distance to the US base and hair metal levels (one at a time) as the predictor variable, controlling for child's age, sex and paternal education. We also explored the mediation of the association between proximity to the base and congenital anomalies by hair metal levels. We found an inverse association between distance to Tallil Air Base and risk of congenital anomalies and hair levels of thorium and uranium. The results of our mediation analyses were less conclusive. Larger studies are necessary to understand the scope of war contamination and its impact on congenital anomalies in Iraq.

Trace element profiling in the incrementally formed dentine of mammalian teeth can be applied to reconstruct temporal variation of incorporation of these elements into the tissue. Using an electron microprobe, this study analysed fluoride distribution in dentine of first and third mandibular molars of free-ranging eastern grey kangaroos inhabiting a high-fluoride area, to assess temporal variation in fluoride uptake of the animals. Fluoride content in the early-formed dentine of first molars was significantly lower than in the late-formed dentine of these teeth, and was also lower than in both, the early and the late-formed dentine of third molars. As early dentine formation in M1 takes place prior to weaning, this finding indicates a lower dentinal fluoride uptake during the pre-weaning compared to the post-weaning period. This is hypothetically attributed to the action of a partial barrier to fluoride transfer from blood to milk in lactating females and a low bioavailability of fluoride ingested together with milk. Another factor contributing to lower plasma fluoride levels in juveniles compared to adults is the rapid clearance of fluoride from blood plasma in the former due to their intense skeletal growth. The combined action of these mechanisms is considered to explain why in kangaroos from high-fluoride areas, the (early-formed) first molars are not affected by dental fluorosis while the (later-formed) third and fourth molars regularly exhibit marked to severe fluorotic lesions.

One of the primary threats to ocean ecosystems from plastic pollution is ingestion by marine organisms. Well-documented in seabirds, turtles, and marine mammals, ingestion by fish and sharks has received less attention until recently. We suggest that fishes of a variety of sizes attack drifting plastic with high frequency, as evidenced by the apparent bite marks commonly left behind. We examined 5518 plastic items from random plots on Kamilo Point, Hawai’i Island, and found 15.8% to have obvious signs of attack. Extrapolated to the entire amount of debris removed from the 15km area, over 1.3tons of plastic is attacked each year. Items with a bottle shape, or those blue or yellow in color, were attacked with a higher frequency. The triangular edges or punctures left by teeth ranged from 1 to 20mm in width suggesting a variety of species attack plastic items. More research is needed to document the specific fishes and rates of plastic ingestion.

High contents of azo dyes and heavy metals enter surface waters with the wastewater from dying and dye-manufacturing industries and pose serious threat to fish. In the present study, changes in the ultra-morphological features of the scale have been evaluated as indicators of the stress of lethal and sublethal concentrations of an azo dye Acid Black-1 (AB-1, CI 20470), zinc (Zn), and their mixture AB-1 + Zn to Labeo rohita. Fish were exposed for 96 h to lethal concentration (LC) causing 0–70% mortality, i.e., LC₀, LC₂₀, LC₅₀, and LC₇₀ of AB-1 (4, 6, 8, and 10 mg/L respectively) and Zn (25, 50, 55, and 60 mg/L respectively) and LC₀, LC₅₀, and LC₇₀ of AB-1 + Zn (2 + 15, 2 + 20, and 2 + 25 mg/L respectively). Subchronic exposures of 150 days were given to 1/12, 1/6, and 1/3 of 96 h LC₅₀ values of AB-1, Zn, and AB-1 + Zn. After each exposure, the fish were kept for a recovery period of 90 days. Breakage of circuli, erosion and breakage of lepidonts, uprooting of tubercles, and disappearance of intercircular teeth were observed in all the fish, after 96 h exposure to AB-1, Zn, and AB-1 + Zn. However, damage to focus and holes were common on the scales of Zn-exposed fish. The mixture AB-1 + Zn was more toxic than either of the two as loss of circuli, lepidonts, and intercircular teeth, and sloughing of surface were observed in the scales after 96 h exposure to 2 + 25 mg/L. Damage at this concentration was more than the damage at 8/10 mg/L AB-1 and 55/60 mg/L Zn. After 150 days of exposure, damage due to sublethal concentrations was more than the damage due to all the concentrations of 96 h exposure. Irregular and sloughed circuli were common at 2 + 1.79 and 2 + 3.59 mg/L AB-1 + Zn. Cracks all over the surface (2 + 7.18 mg/L), calcium projections (2 + 3.59 and 2 + 7.18 mg/L), and holes (2 + 7.18 mg/L) hint towards synergistic toxicity of the mixture. It seems that the present dye and metal formed complexes with collagen and osteoblastic cells of the scale that caused an increase in damage during the post-exposure period. Scales of 2 + 7.18 mg/L AB-1 + Zn exposed fish were completely devoid of the normal architectural pattern on the 90th day of the recovery period. Changes in the ultra-morphology of scales at LC₀ (0% mortality) and sublethal concentrations show that these are early indicators of the stress of minute quantities of dyes and metals in water. This is a first report on the cumulative toxicity of the two most abundant components of textile industry effluents.

Fluoride intake, fluorosis, and dental caries could affect quality of life and disease burden worldwide. As a part of the National and Sub-national Burden of Disease Study (NASBOD) in Iran, we conducted a systematic review to evaluate province-year-specific mean drinking water fluoride concentrations and prevalence of fluorosis and of decayed, missed, and filled teeth (DMFT) in Iran from 1990 to December 2015. We did electronic searches of all English and Persian publications on PubMed, ScienceDirect, Google Scholar, and Iranian databases. Results revealed that the weighted mean drinking water fluoride concentration in Iran from 1990 to 2015 has been about 0.65 ± 0.38 mg/l. However, based on the WHO guideline value (1.50 mg/l) and the maximum permissible Iranian national fluoride standard (1.40 to 2.40 mg/l depending on the region's climate), there have been some regions in Iran with non-optimum fluoride concentrations in their drinking water (up to 7.0 mg/l). Overall, concentrations have been higher in southern parts of Iran and in some areas of Azerbaijan-e-Gharbi Province in the northwest and lower in the rest of the northwest and central parts of Iran. In addition, some hotspots have been found in Bushehr Province, southwest of Iran. The highest prevalence of dental flourosis has been reported in normal index while the lowest prevalence has been expressed in severe index. The lowest DMFT (about 0.1) was in Arsanjan City in Fars Province, and the highest (about 6.7) was for Najaf Abad City in Isfahan Province. Prevalence of fluorosis has been rather high in studied areas of Iran (e.g. 100 % in Maku City in Azarbaijan-e-Gharbi Province), and there was discrepancy for DMFT, but a lack of studies renders the results inconclusive. Further studies, health education and promotion plans, and evidence-based nutrition programs are recommended.

Water fluoridation is considered a cost-effective and practical method for controlling and preventing dental caries in the general population. The objective of this study was to evaluate the dental health status and risk indicators for dental caries in adult Brazilian Indians without exposition to dental caries–preventive effects of water fluoridation. Decayed (DT), missing (MT), and filled (FT) permanent teeth (DMFT), as well as plaque index, unstimulated salivary flow rate, salivary buffering capacity, and fasting blood glucose were examined in 225 adult Indians. Smoking habits and sociodemographic data were evaluated using a structured questionnaire. Drinking water samples from 10 Indian villages were analyzed for the natural fluoride concentration. The mean DMFT was 10.33 ± 6.91 (DT, 4.19 ± 3.99; MT, 4.99 ± 5.64; FT, 1.14 ± 1.75). DMFT index ≥ 9 was associated with age ≥ 35 years (p = 0.000), lower education (p = 0.03), and plaque index > 40% (p = 0.003). DT was associated only with plaque index (p = 0.03). MT was associated with age (p < 0.001) and plaque index (p = 0.01). FT was negatively associated with age (p = 0.02) and income (p = 0.02). Fluoride concentration varied from 0.01 to 0.07 mg/L and was not associated with dental health status (p ≥ 0.29). In conclusion, poorer dental health status was associated with older age, higher plaque index, and lower education and income levels. The fluoride level in the drinking water of Kiriri villages was lower than the level recommended for preventing dental caries. Water fluoridation may be recommended for this population.

The increasing consumption of medications by humans has negative effects such as the increased disposal of these compounds in the environment. Little is known about how the disposal of a “drug mix” (DM) in aquatic ecosystems can affect their biota. Thus, we evaluated whether the exposure of Lithobates casteibeianus tadpoles to a DM composed of different medication classes (antibiotic, anti-inflammatory, antidepressant, anxiolytic, analgesic, and antacid drugs)—at environmentally relevant concentrations—may change their oral morphology, trigger behavioral disorders, and have mutagenic effects on erythrocyte cells. Based on our data, animals exposed to the DM showed changes in mandibular sheath pigmentation, dentition, and swimming activity, as well as atypical behavior in the social aggregation test [with co-specific and interspecific (Physalaemus cuvieri) individuals] and antipredatory defensive response deficit (chemical stimulus from Odonata larvae), after 15 exposure days. The mutagenic analysis revealed higher frequency of nuclear abnormalities in the erythrocytes of tadpoles exposed to the DM (e.g., multilobulated, blebbed, kidney-shaped, notched nucleus, binuclear, and micronucleated erythrocytes). Given the chemical complexity of the DM, we assumed that several organic functions may have been affected, either by the isolated, synergistic, antagonistic, or additive action of DM compounds. Finally, our study confirms the toxicological potential of DM in L. catesbeianus tadpoles, with emphasis to impacts that can affect the fitness of individuals and their natural populations. Thus, we suggest that more attention should be given to the disposal of medications in the environment and reinforce the need of improving water and sewage treatment systems.

Fluoride in trace quantity is beneficial for human beings, serving to strengthen the apatite matrix of skeletal tissues and teeth, whereas high intake causes adverse impacts. In the present study, the effect of fluoride-contaminated drinking water of livestock on the milk samples of different cattle, belonging to a fluoride-endemic area (Tharparkar, Pakistan), was studied. In milk samples of different cattle (cows, camels, sheep, and goats), free and bound fluoride forms and its total (free (F⁻) + bound (F⁻)) contents were measured by ion-selective electrode. The concentration of fluoride in drinking water of livestock was also analyzed, as found in the range of 11.8–33.5 mg/L. The concentration of total fluoride in the milk samples of sheep, goats, cows, and camels were observed in the range of 1.72–2.43, 1.40–2.03, 0.835–1.41, and 0.425–0.897 mg/L, respectively. The resulted data indicated that the concentration of fluoride was higher in the milk samples of smaller cattle (sheep and goat), as compared to cow and camel. The fluoride in milk samples of all cattle appeared dominantly in free form. The percentage values of bound fluoride in the milk samples of sheep, goats, and cows were found to be 6.76, 11.6, and 19.7% in total, respectively, while in camel milk, the percentage was below the detection limit. The estimated daily intake of fluoride contents on consuming different types of milk by children age ranged 1.0 to 3.0 years was evaluated. Graphical abstract ᅟ

It is known that pesticides such as abamectin (ABA) present cytotoxic effects on target organisms; however, the effects from ABA on non-target organisms such as amphibians are poorly understood. The aim of the current study is to investigate whether the exposure of Lithobates catesbeianus tadpoles to different abamectin concentrations [12.5, 25, and 50% of the median lethal concentration (LC₅₀)] leads to behavioral and morphological changes and/or generates possible cytotoxic effects. The aggregation test showed that tadpoles exposed to the highest ABA concentrations did not respond to the stimulus from non-familial and unrelated co-specific species. On the other hand, there was no difference in the total number of crossings in the central line of the herein adopted apparatus between groups; it suggests that ABA did not affect animal locomotion in the aforementioned test, although changes in the normal swimming pattern of tadpoles exposed to the pesticide were recorded in the swimming activity test. In addition, the herein exposed animals did not respond to the predatory stimulus in the antipredator response test; this result suggests defensive response deficit caused by the pesticide. With respect to their oral morphology, tadpoles exposed to ABA presented the lowest scores for mandibular pigmentation and structures, as well as for dentition condition. Finally, it was possible seeing that the exposure to ABA, even at the lowest concentration (12.5% of the LC₅₀), resulted in nuclear changes in the erythrocytes of the animals; these changes became evident in the increased number of micronuclei and in other nuclear abnormalities. Thus, besides confirming the cytotoxic potential of ABA in amphibians, the current study corroborates the hypothesis that the exposure to the herein investigated pesticide leads to behavioral and morphological changes in tadpoles, fact that may negatively reflect on the survival, as well as on natural populations of these individuals.

The objective of this paper was to determine the prevalence and sources of high lead (Pb) exposure among children in Bulacan, Philippines. A total of 150 children (6–7 years old) and their caregivers were studied. Lead was analyzed in children hair and deciduous teeth. Sources of lead exposure were determined by caregiver interview and Pb analysis of house soil, drinking faucet water, air, and water from seven Bulacan rivers. Lead was positive in 91.3 % of children’s hair (MC or median concentration = 8.9 μg/g; range = 0–38.29), in 46.2 % of the teeth (MC = 0.000 μg/mg in positive samples; range = 0.00–0.020), in 100 % of soil (MC = 27.06 mg/kg; range = 3.05–1155.80), in 21.1 % of air (MC = 0 μg/Ncm; range = 0–0.10), in 4 % of house, faucet water (MC = 0.0 ppm; range = 0–40). There was a significant correlation (Spearman’s rho) between Pb in children’s hair and soil (r = 0.195; p = 0.017) and between Pb in house water and outdoor air (r = 0.616; p = 0.005). There is no significant correlation between Pb in children’s hair and teeth. None of the potential sources of Pb from interview were related to lead exposure in the children. Water from seven Bulacan rivers was 100 % positive for lead (MC = 70.00 ppb; range = 30–90). Widespread flooding with river overflow occurred in Bulacan in 2009 which likely caused lead contamination of the soil. There was no significant difference in the lead concentration of the soil whether near or far from the river (p = 0.205, Mann-Whitney U test). High lead exposure in children in Bulacan is likely from soil contaminated by lead-polluted rivers during flooding. In areas where flooding is common, alluvial and riparian soils from polluted rivers are important sources of lead exposure in children.