Incidental Ingestion Research Articles

Manganese relative oral bioavailability in electric arc furnace steel slag is influenced by high iron content and low bioaccessibility

Electric arc furnace (EAF) slag is a rock-like aggregate produced with carbon steel and used for construction, including residential ground cover. It is enriched with manganese (Mn) and other metals, including iron (Fe), but because metals are bound in mineral matrices, in vitro bioaccessibility (BA) is limited. We conducted a relative bioavailability (RBA) study using F344 rats to assess Mn RBA from EAF slag ingestion, compared with Mn in diet. Mn and Fe were measured in liver, and Mn in lung and striatum, the target tissue of the brain. Mn levels in each tissue were fit by dose-to-tissue concentration (D-TC) curves. The D-TC relationship was the most highly significant for the linear model using liver Mn, and the RBA was 48%. The D-TC relationship in lung showed a positive slope for chow, but that for EAF slag was slightly negative, and the RBA was 14%. In comparison, the striatum D-TC remained relatively constant, supporting that homeostasis was maintained. Increased Fe was observed in the liver of EAF slag-dosed groups, suggesting that Mn absorption was inhibited by the high Fe content of slag. Lung and striatum D-TC curves demonstrated that systemic delivery of Mn from EAF slag ingestion is limited and support an RBA of 14% for risk assessment. Although Mn levels in slag are elevated compared with health-based screening guidelines, this study supports that incidental ingestion of Mn in EAF slag is unlikely to pose a neurotoxicity hazard due to homeostatic controls, low BA, and high Fe content.

Transfer of polychlorinated, polybrominated and mixed-halogenated dioxins, furans and biphenyls, polychlorinated naphthalenes and alkanes, polycyclic aromatic hydrocarbons and chlorobenzenes to the milk of dairy cattle from controlled ingestion of industrial and municipal bioresources recycled to agricultural land

Recycled bioresources (biosolids, compost-like-output, meat and bonemeal ash, poultry litter ash, paper sludge ash) were added to the feed of dairy cattle to simulate incidental ingestion from agricultural utilisation, to investigate the transfer of organic contaminants from the ingested materials to milk. The bioresources were blended with a loamy sand soil at agronomic rates to simulate a single application to land, which was added to the diet at 5 % of the total intake on a dry matter (DM) basis. Biosolids, and control treatments consisting of unamended soil, were also added directly to the feed at 5 % DM. The cattle were fed the bioresource amended diets for a target period of three to four weeks, depending on material, and monitoring continued for four weeks after treatment withdrawal. Milk samples were taken weekly with chemical analysis of selected samples for a range of organic contaminants including: polychlorinated, polybrominated and mixed-halogenated dioxins, furans and biphenyls, polychlorinated naphthalenes and alkanes (often called chlorinated paraffins), polycyclic aromatic hydrocarbons and chlorobenzenes.No statistically significant additional transfer of organic contaminants to the milk was detected due to the relatively low levels of contaminants present when the bioresources were incorporated with soil at agronomic rates. However, direct biosolids ingestion by cattle significantly increased the transfer of contaminants to milk in comparison to control animals. Although present in larger concentrations in biosolids than their chlorinated counterparts, the carry over rates and bioconcentration factors of brominated dioxins and furans were considerably smaller. Direct ingestion of biosolids resulted in most contaminants approaching, but not always completely reaching, steady state concentrations within the treatment feeding period, however, concentrations generally declined to control values within four-weeks after withdrawing the biosolids-amended diet.

Role of microbial iron reduction in arsenic metabolism from soil particle size fractions in simulated human gastrointestinal tract

Gut microbiota provides protection against arsenic (As) induced toxicity, and As metabolism is considered an important part of risk assessment associated with soil As exposures. However, little is known about microbial iron(III) reduction and its role in metabolism of soil-bound As in the human gut. Here, we determined the dissolution and transformation of As and Fe from incidental ingestion of contaminated soils as a function of particle size (<250 μm, 100–250 μm, 50–100 μm and < 50 μm). Colon incubation with human gut microbiota yielded a high degree of As reduction and methylation of up to 53.4 and 0.074 μg/(log CFU/mL)/hr, respectively; methylation percentage increased with increasing soil organic matter and decreasing soil pore size. We also found significant microbial Fe(III) reduction and high levels of Fe(II) (48 %−100 % of total soluble Fe) may promote the capacity of As methylation. Although no statistical change in Fe phases was observed with low Fe dissolution and high molar Fe/As ratios, higher As bioaccessibility of colon phase (avg. 29.4 %) was mainly contributed from reductive dissolution of As(V)-bearing Fe(III) (oxy)hydroxides. Our results suggest that As mobility and biotransformation by human gut microbiota (carrying arrA and arsC genes) are strongly controlled by microbial Fe(III) reduction coupled with soil particle size. This will expand our knowledge on oral bioavailability of soil As and health risks from exposure to contaminated soils.

A Case Report on Neurocysticercosis in Children

Abstract: Neurocysticercosis is a parasitic disease which is caused by the incidental ingestion of Taenia solium eggs (pork tapeworm) through the contaminated food. Neurocysticercosis shows its effect on the nervous system and it has been the main cause of acquired epileptic episodes and it was majorly seen in developing countries, and it is more prevalent in some parts of subcontinents like Asia and Sub-Saharan Africa. It was reported that large group of US immigrants are known to suffer from this disease. The major factor which can cause neurocysticercosis is poor sanitation and unhygienic food. The patients may have symptoms of epilepsy, headache, memory problems and thinking problems. Cysterici undergoes different changes in the brain, subarachnoid space and spinal cord leads to Neurocysticercosis. Neurocysticercosis is preventable, and probably eradicable. Eventually, the cysts either resolve or form a calcified granuloma, which is associated with seizures if it is located in the brain. It is estimated that 30% cases will experience epilepsy. Keywords: Neurocysticercosis, Epilepsy, Immune attack.

Exposure to Organophosphate Ester Flame Retardants in the Occupational Environment

Rationale: Flame retardants (FR) are commonly used in consumer products, electronics, and safety equipment. Organophosphate esters (OPEs) are a sub-class of FRs and are widely used in various industries. Occupational risk of exposure is expected for many workers in various industries. However, the evidence of occupational exposure to OPE FRs is limited.&#x0D; Objectives: This study aimed to summarize evidence of occupational exposure to OPE FRs.&#x0D; Methods: A scoping review was conducted using Scopus (April-2022) and Google Scholar (January-2022). Search terms included ""occupational"", ""exposure"", ""flame retardants"", ""organophosphate"" and similar. Studies with quantitative measures of OPE exposure in workplaces were retained. Information on sample types, exposure levels, routes of exposure, and contextual information was extracted and summarized.&#x0D; Results: To-date, 15 studies have met the inclusion criteria. Groups most frequently assessed for OPE exposure include workers in e-waste recycling facilities and constructions. Published studies have described inhalation exposure, incidental ingestion, and dermal absorption routes. Sampling methods included active air sampling, passive air sampling, biological sampling, and dermal sampling. Triphenyl phosphate (TPhP), Tris(2-chloroisopropyl) phosphate (TCIPP), and Tris(2-chloroethyl) phosphate (TCEP) were the three most common sampled OPEs.&#x0D; Conclusions: There is evidence of OPE exposure in a limited number of industries and occupations at levels higher than the general population. The adverse health effects associated with OPE exposure included reproductive complications, endocrine disruption, and potential carcinogenicity. More research is needed to understand the prevalence and level of occupational exposure to OPE FRs and the potential work-related health impacts.

Human health risk associated with metal exposure at Agbogbloshie e-waste site and the surrounding neighbourhood in Accra, Ghana

Agbogbloshie in Accra, Ghana, was a center for informal e-waste recycling until it was closed recently. This study investigated the potential health risks of toxic metals (including As, Cd, Cu, Ni, Pb, Sb, and Zn) found in the surface soils based on their concentrations and in vitro bioaccessibility. Mean concentrations at the burning sites were As: 218; Cd: 65; Cr: 182; Cu: 15,841; Ni: 145; Pb: 6,106; Sb: 552; and Zn: 16,065 mg/kg while the dismantling sites had mean concentrations of As: 23; Cd: 38; Cr: 342; Cu: 3239; Ni: 96; Pb: 681; Sb: 104; and Zn: 1658 mg/kg. The findings confirmed the enrichment of potentially toxic metals at the dismantling and burning sites, exceeding international environmental soil quality guidelines. Based on the total metal concentrations, bioaccessibility, and calculated risk indices, the risks associated with incidental ingestion of soil-borne metal contaminants at the dismantling and burning sites were very high. Despite evidence of higher metal concentrations in the communities near the burning and dismantling sites, the human health risk associated with soil ingestion was significantly lower in the surrounding neighborhood.

Interactions of microplastics with contaminants in freshwater systems: a review of characteristics, bioaccessibility, and environmental factors affecting sorption

Microplastics (MPs), plastic particles of 1 nm to <5 mm, have been identified in the atmosphere, soil, and aquatic environments across the globe. MPs may act as vectors to transport environmental contaminants to sensitive receptors, including humans. In this review, the capability of MPs to sorb persistent organic pollutants (POPs) and metals is investigated, along with how sorption is affected by factors, such as pH, salinity, and temperature. Sensitive receptors may take up MPs through incidental ingestion. In the gastrointestinal tract (GIT), contaminants may desorb from MPs, and this desorbed portion is then considered bioaccessible. Understanding the sorption and bioaccessibility of such contaminants is important in determining potential risks of exposure to MPs. Thus, a review is presented on the bioaccessibility of contaminants sorbed to MPs in the human and avian GIT s. The current state of knowledge on MP-contaminant interactions in freshwater systems is limited; these interactions can differ considerably from those in marine environments. The bioaccessibility of contaminants sorbed to MPs can vary significantly, from near zero to 100%, depending on MP type, contaminant characteristics, and the digestive phase. Further research is needed to characterize the bioaccessibility and the potential risks, especially for POPs associated with MPs.

Combining Contamination Indices and Multivariate Statistical Analysis for Metal Pollution Evaluation during the Last Century in Lacustrine Sediments of Lacu Sărat Lake, Romania.

Integrated study of both water and sediment in lakes provides important information regarding the human impact on the environment. The current work is focused on the correlation between age, source, composition, and degree of human intervention over the last 178 years and health impact of sediments from Lacu Sărat Lake (Romania), one of the most important balneo-climateric resorts in the country. The novelty relies on the fact that this is the first time the temporal patterns of metal contamination and the human health effects associated with the metal exposure from sediment core samples have been assessed. The sediment contamination status was determined by evaluating several indices, such as the enrichment factor, geo-accumulation index, metal pollution index, and potential ecological risk index, etc. Results showed a significant accumulation of Cd, Cr, As and Ni and a major contribution of Pb, Zn, Cd, Hg, Cr as well as Cu to the potential acute toxicity. The sediment quality guidelines emphasized a risk concerning the life and proper development of benthic organisms in Lacu Sărat Lake. Moreover, the incidental ingestion lifetime carcinogenic risk values for As and Cr suggest a potential risk of developing cancer. A strong human impact was observed especially between 1950 and 1990, which can be attributed to the rapid economic growth and intensive industrial development strategies pursued by the communist political regime in Romania.

Molecular identification of individual and seasonal variation in incidental ingestion of arthropods by free-ranging goats

The extent of direct interactions between large mammalian herbivores (LMH) and plant-dwelling arthropods (PDA), i.e., the ingestion of PDA by LMH, remains largely unexplored. Grazing LMH may ingest a variety of PDA, yet, it is unknown how different foraging strategies (i.e., browsing, grazing, etc.) influence the ingestion of PDA or whether individual variation within herds affects it. Here we examine how individual variation within a herd of browsing LMH impacts PDA ingestion. This was done using a DNA metabarcoding analysis on feces collected monthly from marked individuals within a herd of free-ranging goats. We found that goats frequently ingest PDA while feeding (all samples contains PDA), including a complex food-chain of herbivores, predators and parasites, which differed over the season and among individual goats. In total, 63 families of insects and 9 families of arachnids from 15 orders were ingested by the goats. Most ingested PDA were herbivores with reduced mobility, such as immature or sessile species. Highly mobile and noxious PDA were rarely detected. We show for the first time that ingestion of PDA by LMH is influenced by seasonal and individual variation within the herd and that it is common among LMH, regardless of feeding strategy or habitat.

Detection of microplastic particles in scats from different colonies of California sea lions (Zalophus californianus) in the Gulf of California, Mexico: A preliminary study

Microplastics (MPs, < 5 mm in size) are highly bioavailable to many taxa within the marine ecosystem, either ingested directly or indirectly through trophic transfer from polluted prey. The ingestion analysis of these MPs from top predators, such as pinnipeds in Mexico, is relatively unexplored. Forty-eight scats from California sea lions were collected on six rookeries along the Gulf of California. From these scat samples, 294 suspected MPs particles were classified and chemically analyzed; 34% were synthetic and semi-synthetic, and 66% were non-synthetic. Blue-colored polyethylene terephthalate fibers were the most common type of MP registered. During laboratory work, multiple contamination control measures were implemented. Although the ingestion pathway is still unknown, our results support the other authors that suggest the potential trophic transfer of MPs to top predators and incidental ingestion while foraging. The particles documented here provide important baseline information for future MP research in the Gulf of California.

Decreased in vitro bioaccessibility of Cd and Pb in an acidic Ultisol through incorporation of crop straw-derived biochar

Studies analyzing the in vitro bioaccessibility (BAc) of heavy metals in biochar-amended soils are currently lacking. The present study aimed to assess the metal BAc in Cd- and Pb-spiked acidic Ultisol samples treated individually with 2% (w/w) maize, rice, wheat, soybean, and pea straw-derived biochar. The results indicate that the Cd-BAc simulated in gastric phase (GP) decreased from 78.4% to 66.5–72.3% and the Pb-BAC decreased from 74.3% to 67.2–69.2%; however, the Cd-BAc in the intestinal phase (IP) decreased from 35.6% to 27.9–33.5% and the Pb-BAc decreased from 34.7% to 29.7–32.9% after 120 d of incubation with biochar application compared to the un-amended Ultisol. The Cd- and Pb-BAc in both GP and IP were significantly negatively correlated with soil pH, CEC, and organic carbon (P < 0.05), which increased after biochar application. The soybean straw-derived biochar amendment has the greatest potential to decrease the BAc of Cd and Pb in the GP and IP, owing to the highest level of CEC, SOC, TC and TN among all soil samples. Moreover, the BAc was positively correlated with the exchangeable, and exchangeable + carbonate-bound Cd and Pb fractions (P < 0.05), indicating these fractions had a dominant influence on the BAc of cationic heavy metals. Therefore, crop straw-derived biochar amendment can decrease the BAc of Cd and Pb in acidic Ultisol, and thus mitigate the health risks posed by these metals from incidental ingestion.

Evaluation of the Safety and Efficacy of Hand Sanitizer Products Marketed to Children Available during the COVID-19 Pandemic.

Hand sanitizer use in the United States (U.S.) increased after the SARS-CoV-2 outbreak. The U.S. Food and Drug Administration (FDA) released temporary manufacturer guidance, changing impurity level limits for alcohol-based hand sanitizers (ABHSs). Since the guidance took effect, the FDA has recommended against using these hand sanitizers due to concerns over safety, efficacy, and/or risk of incidental ingestion. To address current gaps in exposure characterization, this study describes a survey of ABHSs marketed to children available in the U.S., as defined by several inclusion criteria. A subset of ABHSs (n = 31) were evaluated for ethanol and organic impurities using a modified FDA method. Products with detectable impurity levels were compared to the FDA's established interim limits. Seven children's products had impurity levels exceeding the FDA's recommended interim limits, including benzene (up to 9.14 ppm), acetaldehyde (up to 134.12 ppm), and acetal (up to 75.60 ppm). The total measured alcohol content ranged from 52% to 98% in all hand sanitizers tested, ranging from 39% below, and up to 31% above, the labeled concentration. Future studies should confirm impurity contamination sources. A risk assessment could determine whether dermal application or incidental ingestion of impurity-containing hand sanitizers pose any consumer risk.

Contaminant Binding and Bioaccessibility in the Dust From the Ni-Cu Mining/Smelting District of Selebi-Phikwe (Botswana).

We studied the dust fractions of the smelting slag, mine tailings, and soil from the former Ni-Cu mining and processing district in Selebi-Phikwe (eastern Botswana). Multi-method chemical and mineralogical investigations were combined with oral bioaccessibility testing of the fine dust fractions (<48 and <10μm) in a simulated gastric fluid to assess the potential risk of the intake of metal(loid)s contaminants. The total concentrations of the major contaminants varied significantly (Cu: 301-9,600mg/kg, Ni: 850-7,000mg/kg, Co: 48-791mg/kg) but were generally higher in the finer dust fractions. The highest bioaccessible concentrations of Co, Cu, and Ni were found in the slag and mine tailing dusts, where these metals were mostly bound in sulfides (pentlandite, pyrrhotite, chalcopyrite). On the contrary, the soil dusts exhibited substantially lower bioaccessible fractions of these metals due to their binding in less soluble spinel-group oxides. The results indicate that slag dusts are assumed to be risk materials, especially when children are considered as a target group. Still, this exposure scenario seems unrealistic due to (a) the fencing of the former mine area and its inaccessibility to the local community and (b) the low proportion of the fine particles in the granulated slag dump and improbability of their transport by wind. The human health risk related to the incidental ingestion of the soil dust, the most accessible to the local population, seems to be quite limited in the Selebi-Phikwe area, even when a higher dust ingestion rate (280mg/d) is considered.

Food grown on fire stations as a potential pathway for firefighters' exposure to per- and poly-fluoroalkyl substances (PFAS).

Human exposure to per- and polyfluoroalkyl substances also known as PFAS is an ongoing occupational and environmental health problem. This study seeks to characterise multiple pathways for firefighters' exposure to PFAS. PFAS were analysed in 688 environmental samples such as eggs, fruits, vegetables, dust, soil, surface swabs, appliance washes and water obtained from fire stations. Relevant exposure pathways were identified and daily intake levels were estimated using PFAS concentrations and exposure factors relevant to firefighters. Five PFAS including perfluorooctane sulfonic acid (PFOS), perfluorooctanoic acid (PFOA), perfluorohexane sulfonic acid (PFHxS), 6:2 fluorotelomer sulfonate (6:2 FTS), and 8:2 fluorotelomer sulfonic acid (8:2 FTS) were frequently detected in the samples. Based on the median concentrations in each sample type, PFOS was the most abundant contaminant in eggs (80%), fruits (52%), dust (81%), surface swab (66%), soil (83%) and appliance wash (31%) samples. On the other hand, PFHxS was most abundant in vegetables (77%) and 8:2 FTS in water (58%). The intake estimation results show that dietary exposure from ingestion of foods produced on fire stations was the predominant exposure pathway, representing 82% and 62% of firefighters' total PFAS intake under typical and worst-case exposure scenarios, respectively. Incidental ingestion and dermal absorption of PFAS in dust contributed 15% for typical and 34% for worst-case exposure scenarios. The relative contributions from incidental ingestion and dermal absorption of PFAS in soil and appliance washes were insignificant. Overall, the study identifies multiple exposure pathways relevant to career firefighters including consumption of food grown on fire stations, which has not previously been recognised within the occupational exposure context. The results suggest exposure control strategies that target foods produced on fire stations could substantially reduce firefighters' exposure to PFAS.

Assessment of unsafe disposal of unused and expired medicines practices among households in North-west Nigeria

Background: Unsafe disposal of unwanted medicines continues to be of global concern. Data on such disposal practices among households and the availability of national drug disposal programmes are limited in Nigeria. This study was carried out to assess the practice of unsafe disposal of unused and expired medicines in north-west Nigeria. Methods: This was a cross-sectional study with participants recruited into the study using an online survey (via Google Forms®) and face-to-face interviews. A hyperlink to the online questionnaire was shared with the targeted population through emails and social media platforms. Results: A total of 319 valid responses were included in the analysis, of which 60.2% reported practicing unsafe disposal of unused and expired medications. The most utilized disposal methods were discarding in the domestic dustbin (52.6%), burning (10.6%), toilet sink (9.4%), and water drain (9.4%). Frequently involved medicines were analgesics (32.6%), antibiotics (24.4%), and antimalarials (21.7%). Most of the practice resulted from non-adherence (34.9%), self-medication (23.6%), polypharmacy (23.4%), adverse effects (18.1%), and incidental ingestion by children (9.4%). Participants (86.2%) are aware of the health hazards related to the practice, and (95.3%) were willing to comply with the RUM concept. Conclusion: Given the high prevalence of unsafe disposal practices of unused and expired medicines in the community vis-à-vis their ecotoxicological implications, a spontaneous review of the current national medicines' disposal regulations jointly by the Federal Ministry of Health and the Federal Ministry of Environment that would include interventions such as Return Unused Medicines is highly recommended.

Assessing the impact of COVID-19 restrictions on the microbial quality of an urban water catchment and the associated probability of waterborne infections

The World Health Organization reported that COVID-19 cases reached 611,421,786 globally by September 23, 2022. Six months after the first reported case, the disease had spread rapidly, reaching pandemic status, leading to numerous preventive measures to curb the spread, including a complete shutdown of many activities worldwide. Such restrictions affected services like waste management, resulting in waste accumulation in many communities and increased water pollution. Therefore, the current study investigated if lockdown impacted surface water microbial quality within an urban water catchment in South Africa. Using quantitative microbial risk assessment, the study further assessed changes in the probability of infection (Pi) with gastrointestinal illnesses from exposure to polluted water in the catchment. Escherichia coli data for 2019, 2020 and 2021 – pre-COVID, lockdown, and post-lockdown periods, respectively – were collected from the area's wastewater treatment management authorities. The Pi was determined using a beta-Poisson model. Mean overall E. coli counts ranged from 2.93 ± 0.16 to 5.30 ± 1.07 Log10 MPN/100 mL. There was an overall statistically significant increase in microbial counts from 2019 to 2021. However, this difference was only accounted for between 2019 and 2021 (p = 0.008); the increase was insignificant between 2019 and 2020, and 2020 and 2021. The Pi revealed a similar trend for incidental ingestion of 100 mL and 1 mL of polluted water. No statistically significant difference was observed between the years based on multiple exposures. Although the overall microbial load and Pi estimated within the catchment exceeded the local and international limits recommended for safe use by humans, especially for drinking and recreation, these were not significantly affected by the COVID-19 restrictions. Nevertheless, these could still represent a health hazard to immunocompromised individuals using such water for personal and household hygiene, especially in informal settlements without access to water and sanitation services.

Aquifer vulnerability assessment for fecal coliform bacteria using multi-threshold logistic regression.

Assessing aquifer vulnerability is crucial for preventing groundwater pollution. In this study, aquifer vulnerability to fecal coliform (FC) pollution was assessed using auxiliary environmental data in the Pingtung Plain, Taiwan. Moreover, key environmental factors inducing different fecal pollution levels were determined. First, 23 explanatory variables on land uses, population density, livestock and poultry densities, sanitary condition, antecedent precipitation, groundwater quality, aquifer characteristics, and subsurface hydrology were obtained using geographic information systems in 2014. As dependent variables, groundwater FCs were also simultaneously obtained. Then, multi-threshold logistic regression (LR) was adopted to model aquifer vulnerability assessment after cross validation. The thresholds of aquifer vulnerability causing risks of incidental ingestion were analyzed by risk assessment. Risks to human health were acceptable for a low-level threshold and exceeded the acceptable level for medium- and high-level thresholds when residents incidentally ingested FC-polluted groundwater. Finally, key environmental factors inducing low, medium, and high levels of groundwater FC pollution were characterized. The key environmental factors for the LR with low- and medium-level thresholds were sand and gravel soil textures of unsaturated aquifers and antecedent 3-day cumulative precipitation, and those for the LR with high-level thresholds were chicken farming, urban land use, and ratio of tap water use. Thus, the multi-threshold LR indicated that environmental factors must be ranked for assessing aquifer vulnerability.

High lead exposure and clinical signs of toxicosis in wild Nile crocodiles (Crocodylus niloticus) from a World Heritage site: Lake St Lucia estuarine system, South Africa.

Lead (Pb) exposure is a widespread wildlife conservation threat, but impacts on reptile populations remain poorly documented. In this study, we examined Pb exposure and accumulation in a wild population of Nile crocodiles (Crocodylus niloticus) at Lake St Lucia, South Africa. Recreational angling has occurred in the area since the 1930s and incidental ingestion of Pb fishing weights has previously been identified as a major source of Pb poisoning in the local crocodile population. In 2019, we sampled blood and tail fat tissues from wild (n=22) and captive (n=3) crocodiles at Lake St Lucia to investigate potential impacts of chronic Pb exposure on crocodilian health. Lead was detected in blood samples of all wild crocodiles, although concentrations varied widely between individuals (86-13,100ngml-1). The incidence of Pb poisoning was higher in male crocodiles, with mean blood lead (BPb) concentrations in males (3780±4690ngml-1) significantly (p<0.001) higher compared to females (266±230ngml-1). Blood Pb concentrations were correlated with concentrations measured in tail fat tissue (n.d - 4175ngg-1 wet wt.). Although most of the crocodiles sampled appeared to be in good physical condition, highly elevated BPb concentrations (>6000ngml-1) were associated with markedly suppressed packed cell volumes (4.6-10.8%) and severe deterioration in tooth condition. These findings suggest that anaemia and tooth loss may be clinical signs of long-term environmental exposure to Pb. Although previously undocumented in crocodilians, these symptoms are consistent with Pb poisoning observed in birds and mammals, and suggest that crocodilians may be more susceptible to the long-term toxic effects of Pb than previously thought. In light of these findings, we suggest that the impact of accumulated Pb on crocodilian fitness, reproduction and mortality requires urgent attention.

Model-based predictions of soil and dust ingestion rates for U.S. adults using the stochastic human exposure and dose simulation soil and dust model

BackgroundAdults can be exposed to chemicals through incidental ingestion of soil and dust, either through hobbies, occupations, or behaviors that increase contact with soil or dust (e.g., cleaning or renovating). However, few data describing these ingestion rates are available. ObjectiveOur objective was to use the Stochastic Human Exposure and Dose Simulation Soil and Dust (SHEDS-Soil/Dust) model to estimate distributions of soil and dust ingestion rates for adults (≥21 years old) with varying degrees of soil and dust contact. MethodsWe parameterized SHEDS-Soil/Dust to estimate soil and dust ingestion rates for several categories of adults: adults in the general population; adults with moderate (higher) soil exposure (represented by hobbyists, such as gardeners, with increased soil contact); adults with high soil exposure (represented by occupationally exposed individuals, such as landscapers); and individuals who have high dust exposure (e.g., are in contact with very dusty indoor environments). ResultsTotal soil plus dust ingestion for adults in the general population was 7 mg/day. Hobbyists or adults with moderate soil exposure averaged 33 mg/day and occupationally exposed individuals averaged 123 mg/day. Total soil plus dust ingestion for adults in the high dust exposure scenario was 25 mg/day. Results were driven by time spent in contact with soil and, thus, warmer seasons (e.g., summer) were associated with higher ingestion rates than colder seasons (e.g., winter). SignificanceThese results provide modeled estimates of soil and dust ingestion rates for adults for use in decision making using real-world exposure considerations. These modeled estimates suggest that soil and dust ingestion is a potential concern for adults who spend a higher amount of time interacting with either soil or dusty environments. Impact statementThe parameterization of real-world scenarios within the application of SHEDS-Soil/Dust model to predict soil and dust ingestion rates for adults provides estimates of soil and dust ingestion rates useful for refining population-based risk assessments. These data illuminate drivers of exposure useful for both risk management decisions and designing future studies to improve existing tracer methodologies.

Ask the shark: blackmouth catshark (Galeus melastomus) as a sentinel of plastic waste on the seabed

The presence of plastic waste in the marine environment has driven the scientific community to make significant efforts to study and mitigate its possible effects. One of the critical aspects is to determine if and how an increase in ingestion events may occur as a result of the accumulation of plastic waste on the seabed. In this study, G. melastomus is examined for its ability to indirectly provide information on the amount of macroplastics accumulating on the seafloor. Plastic ingestion is explored by describing the feeding habits of the species, which have the potential to provide very useful information regarding biological or ecological issues. The diet of G. melastomus mainly consisted of cephalopods, bathypelagic fishes, and decapod crustaceans, increasing in diversity during growth. The generalist-opportunistic feeding behaviour of this species leads to the incidental ingestion of plastic particles (N = 47, with a mean (± SD) of 1.47 ± 0.28 per specimen) which can be indirectly associated to the presence of macroplastics on the seafloor. Indeed, our results indicate a significant relationship between the amount of macroplastics present on the seabed and the frequency of ingestion of plastic particles by blackmouth catshark. We propose G. melastomus as an excellent candidate for developing a valid monitoring strategy for the presence of plastics on the seabed, as requested by the EU Marine Strategy Framework Directive.