In the last decade many studies have described the ingestion of plastic in marine animals. While most studies were dedicated to understanding the pre-ingestion processes involving decision-making foraging choices based on visual and olfactory cues of animals, our knowledge in the post-ingestion consequences remains limited. Here we proposed a theoretical complementary view of post-ingestion consequences, attempting to connect plastic ingestion with plastic-induced satiety. We analyzed data of plastic ingestion and dietary information of 223 immature green turtles (Chelonia mydas) from tropical Brazilian reefs in order to understand the impacts of plastic ingestion on foraging behavior. Generalized linear mixing models and permutational analysis of variance suggested that plastic accumulations in esophagus, stomach and intestine differed in their impact on green turtle’s food intake. At the initial stages of plastic ingestion, where the plastic still in the stomach, an increase in food intake was observed. The accumulation of plastic in the gastrointestinal tract can reduce food intake likely leading to plastic-induced satiety. Our results also suggest that higher amounts of plastics in the gastrointestinal tract may led to underweight and emaciated turtles. We hope that adopting and refining our proposed framework will help to clarify the post-ingestion consequences of plastic ingestion in wildlife.

Long-term exposure to PM₂.₅ has been linked to lung cancer incidence and mortality, but limited evidence existed for other cancers. This study aimed to assess the association between PM₂.₅ on cancer specific mortality. An ecological study based on the cancer mortality data collected from 5,565 Brazilian cities during 2010–2018 using a difference-in-differences approach with quasi-Poisson regression, was applied to examine PM₂.₅-cancer mortality associations. Globally gridded annual average surface PM₂.₅ concentration was extracted and linked with the residential municipality of participants in this study. Sex, age stratified and exposure-response estimations were also conducted. Totalling 1,768,668 adult cancer deaths records of about 208 million population living across 5,565 municipalities were included in this study. The average PM₂.₅ concentration was 7.63 μg/m³ (standard deviation 3.32) with range from 2.95 μg/m³ to 28.5 μg/m³. With each 10 μg/m³ increase in three-year-average (current year and previous two years) concentrations of PM₂.₅, the relative risks (RR) of cancer mortality were 1.16 (95% confidence interval [CI]: 1.11–1.20) for all-site cancers. The PM₂.₅ exposure was significantly associated with several cancer-specific mortalities including oral, nasopharynx, oesophagus, and stomach, colon rectum, liver, gallbladder, larynx, lung, bone, skin, female breast, cervix, prostate, brain and leukaemia. No safe level of PM₂.₅ exposure was observed in the exposure-response curve for all types of cancer. In conclusion, with nationwide cancer death records in Brazil, we found that long-term exposure to ambient PM₂.₅ increased risks of mortality for many cancer types. Even low level PM₂.₅ concentrations had significant impacts on cancer mortality.

A study was conducted to quantify the abundance of plastic pollution in the gastrointestinal tracts in birds of prey. Data was collected from all birds retrieved from the Audubon Center for Birds of Prey in central Florida, USA from January to May 2018. Individuals were either dead prior to reaching the Center or died within 24 h of arrival with no food consumed during captivity. Sixty-three individuals representing eight species were dissected to extract the gastrointestinal (GI) tract from the esophagus to the large intestine. Microplastics were found in the GI tracts in all examined species and in all individual birds. The overall mean number (±S.E.) of microplastics for species of bird of prey in central Florida was 11.9 (±2.8), and the overall mean number of microplastics per gram of GI tract tissue was 0.3 (±0.1). A total of 1197 pieces of plastic were recorded. Microfibers accounted for 86% of total plastics followed by microfragments (13%), macroplastics (0.7%) and microbeads (0.3%). Most fibers were either clear or royal blue in color. Micro-Fourier-transform infrared spectroscopy (μ-FTIR) found that processed cellulose was the most common polymer identified in birds (37%), followed by polyethylene terephthalate (16%) and a polymer blend (4:1) of polyamide-6 and poly(ethylene-co-polypropylene) (11%). Two bird species, Buteo lineatus (red-shouldered hawk, n = 28) and Pandion haliaetus (osprey, n = 16), were sufficiently abundant to enable statistical analyses. Microplastics were significantly more abundant per gram in the gastrointestinal tract tissue of B. lineatus, that consumes small mammals, snakes, and amphibians, than in fish-feeding P. haliaetus (ANOVA: p = 0.013). If raptors in terrestrial food webs have higher densities of microplastics than aquatic top predators, then it potentially could be due to a combination of direct intake of plastics and indirect consumption via trophic transfer.

The deleterious effects of marine debris ingestion on marine turtles are well documented in literature globally. In this study, the qualitative and quantitative aspects of marine debris ingested by 14 stranded green sea turtles Chelonia mydas, (Linnaeus, 1758) along the eastern coast of the United Arab Emirates were investigated. The numeric and gravimetric proportions of debris in the esophagus, stomach and intestines were documented following classification of color, presumed sources and Marine Strategy Framework Directive categories and sub-categories. The results show that 85.7% of the specimens examined consumed marine debris. On average, specimens consumed 61.9 ± 17.2 items of 1.0 ± 0.3 g mass. Plastics, particularly white, and transparent thread-like and sheet-like plastics, were the predominant debris ingested. The results reflect a potentially high level of interaction between green sea turtles and anthropogenic marine debris along the Gulf of Oman coast of the UAE.

Assessment of marine debris ingestion by sea turtles is important, especially to ensure their survival. From January to December 2011, 23 specimens of five species of sea turtles were found dead or dying after being rehabilitated, along the coast of the municipality of Rio de Janeiro, Brazil. To detect the presence of marine debris in the digestive tract of these turtles, we conducted a postmortem examination from the esophagus until the distal portion of the large intestine for each specimen. Of the total number of turtles, 39% had ingested marine debris such as soft plastic, hard plastic, metal, polyethylene terephthalate (PET) bottle caps, human hair, tampons, and latex condoms. Five of the seven sea turtles species are found along the Brazilian coast, where they feed and breed. A large number of animals are exposed to various kinds of threats, including debris ingestion.

For the first time, the qualitative and quantitative characteristics of marine debris ingested by six hawksbill (Eretmochelys imbricata) and seven olive ridley (Lepidochelys olivacea) sea turtles from the Gulf of Oman coast of the United Arab Emirates were investigated. The numeric and gravimetric proportions of ingested marine debris obtained from the esophagus, stomach and intestines were quantified following categories of presumed sources, Marine Strategy Framework Directive (MSFD), rigidity, color and plastic polymer types. Marine debris was observed in 28.6% of olive ridley (x̅: 2.00 items; 4.83 g) and 83.3% of hawksbill specimens (x̅: 6.00 ± 2.32 items; 0.32 ± 0.24 g). Overall, the results of this preliminary study suggest that hawksbill sea turtles were ingesting marine debris at higher frequencies and that plastics were observed to be the most predominant debris ingested. However, non-plastic rubbish, particularly metallic fishing gear (fish hooks and fish traps), were observed to present lethal hazards for both species.

Pregnancy and feto-gestational toxicities on exposure to fluoride and its possible amelioration on co-administration with aloe vera were studied in pregnant Swiss albino mice. Once the confirmed pregnancy was tested, animals were equally divided into four groups as follows: group I was given no treatment and served as control, and groups II and III were administered with 100 and 300 ppm sodium fluoride, respectively, while group IV was co- administered aloe vera (300 mg/kg bw) along with sodium fluoride (300 ppm) daily for 14 days prior to gestation and continued till the 18th day of gestation. Animals were sacrificed on the 19th day of gestation for prenatal observations. Maternal body weight, the gravid uterine weight, number of corpora lutea in both the ovaries, number of implantations and resorptions, number of live (mature and immature) fetuses, and number of dead fetuses were examined in each dam. The treatment continued in another set of animals till the completion of the weaning period to observe postnatal changes due to test substances on the mother and pups. Sodium fluoride–treated animals showed morphometric and skeletal changes which were more pronounced in the high-dose group showing significantly decreased body weight gain in pregnant mothers and dead/immature fetuses. Morphometric changes included open eyelids, limb defects, wrinkles on the whole body, anophthalmia, pulmonary edema, enlarged esophagus, and decreased body weight of fetuses and pups. Alizarin-prepared skeletal structures of fetuses of such female mice showed delayed ossification or bending in the number of bones of skull, thoracic, and limb regions. However, concomitant exposure to sodium fluoride and aloe vera in treated animals led to a marked improvement in all the prenatal and postnatal variables. The study suggests that sodium fluoride at high concentrations may be teratogenic while co-administration of aloe vera during fluoride exposure might be beneficial in reducing these toxic effects. The use of aloe vera as a preventive agent or as a complimentary agent is thus recommended following fluoride exposure through the oral route.

Glyphosate-based herbicides (GBH) are the most widely used herbicide for treatment of crops in the world. The digestive tract is one of the first systems exposed to pesticides, and damage to this system can affect the general health of individuals. The aim of this study was to evaluate the effects of subchronic inhalation and oral exposure to GBH on the digestive tract in rats. Six groups of Wistar rats (male and female) were exposed to nebulization with three concentrations of GBH [3.71 × 10⁻³ grams of active ingredient per hectare (g.a.i./ha), 6.19 × 10⁻³ g.a.i./ha and 9.28 × 10⁻³ g.a.i./ha] administered orally or by inhalation for 75 days. Bone marrow cells, smears of the tongue and fragments of the tongue, oesophagus, stomach and intestine were collected for histopathological analysis. Congestion, inflammation, an increase in the number of mast cells and nucleoli-organizing regions were detected in the tongue in the groups exposed to GBH. Females had a higher number of mast cells in the tongue than males. Animals in the groups exposed to higher concentrations of GBH showed dysplasia in the oesophagus and small and large intestine regardless of sex. Gastric changes were not observed. Animals exposed to GBH showed increased micronucleus formation. Our data indicate that GBH causes oral allergies and dysplastic lesions in the oesophagus and small and large intestine and has genotoxic potential.

Spatio-temporal cancer mortality studies in Spain have revealed patterns for some tumours which display a distribution that is similar across the sexes and persists over time. Such characteristics would be common to tumours that shared risk factors, including the chemical soil composition. The objective of the present study is to assess the association between levels of chromium and arsenic in soil and the cancer mortality. This is an ecological cancer mortality study at municipal level, covering 861,440 cancer deaths in 7917 Spanish mainland towns from 1999 to 2008. Chromium and arsenic topsoil levels (partial extraction) were determined by ICP-MS at 13,317 sampling points. To estimate the effect of these concentrations on mortality, we fitted Besag, York and Mollié models, which included, as explanatory variables, each town’s chromium and arsenic soil levels, estimated by kriging. In addition, we also fitted geostatistical-spatial models including sample locations and town centroids (non-aligned data), using the integrated nested Laplace approximation (INLA) and stochastic partial differential equations (SPDE). All results were adjusted for socio-demographic variables and proximity to industrial emissions. The results showed a statistical association in men and women alike, between arsenic soil levels and mortality due to cancers of the stomach, pancreas, lung and brain and non-Hodgkin’s lymphomas (NHL). Among men, an association was observed with cancers of the prostate, buccal cavity and pharynx, oesophagus, colorectal and kidney. Chromium topsoil levels were associated with mortality among women alone, in cancers of the upper gastrointestinal tract, breast and NHL. Our results suggest that chronic exposure arising from low levels of arsenic and chromium in topsoil could be a potential risk factor for developing cancer.

This study was conducted to investigate the association between trace elements including cadmium (Cd), chromium (Cr), cobalt (Co), copper (Cu), iron (Fe), lead (Pb), nickel (Ni), selenium (Se), zinc (Zn), and arsenic (As) in gastrointestinal cancer tissue and non-cancerous tissue (suspected gastrointestinal cancer) in Eastern Iran. The samples of 63 gastrointestinal cancers (stomach (n = 20), esophageal (n = 19), and colorectal (n = 24) along with 63 controls in South Khorasan Province, Iran, were collected and analyzed using ICP-MS (Agilent 7900). Our results indicated that the concentrations of Co (1.3 ± 0.8, 1.3 ± 0.8 μg kg⁻¹), Cr (8.1 ± 7.3, 11.0 ± 14.8 μg kg⁻¹), Ni (29.0 ± 20.1, 39.5 ± 30.2 μg kg⁻¹), Pb (6.9 ± 4.0, 6.1 ± 4.6 μg kg⁻¹), and Zn (867.6 ± 159.1, 935.6 ± 196.2 μg kg⁻¹) were significantly higher among esophagus and colon cancer cases than controls (p < 0.05). Similarly, stomach cancer cases showed higher Co, Cr, Ni, Se, and Zn and lower Cu concentrations than their controls (p < 0.05). Moreover, the Spearman correlation between metals revealed a mostly low to moderate correlation between metals. Our finding illustrated that the significant risk differences of Cr, Ni, Pb, Se, and Zn metals on esophagus cancer when considered the single predictor unadjusted for other metals and covariates RD (95% CI) – Cr: −0.274 (−0.463, −0.086), Ni: −0.288 (−0.457, −0.118), Pb: −0.171 (−0.463, −0.086), Se: −0.243 (−0.434, −0.051), and Zn: −0.094 (−0.143, −0.045) respectively. This study suggests that the trace element’s exposure may be associated with gastrointestinal cancer risk. Additional studies are needed to elucidate the mechanisms underlying trace element carcinogenesis further.