Exposure to Contaminated River Water is Associated with Early Hatching and Dysregulation of Gene Expression in Early Life Stages of the Endangered Copper Redhorse (Moxostoma hubbsi).

The copper redhorse (Moxostoma hubbsi) is an endangered fish that spawns exclusively in the Richelieu River (Quebec, Canada). Tributaries of the Richelieu are contaminated with high levels of current-use pesticides, which may impact early-life stage (ELS) copper redhorse and other native fishes. We assessed the effects of exposure to contaminated river water on ELS copper redhorse and river redhorse (Moxostoma carinatum), a related fish that shares the copper redhorse's spawning grounds and nursery habitat. A riverside flow-through system was used to expose copper and river redhorse embryos (1000 each) to Richelieu River water or laboratory water as a control. Fish were maintained until 14 days posthatch, and water samples were taken daily for chemical analysis. Following a heavy rain event, concentrations of two neonicotinoid pesticides, clothianidin and thiamethoxam, exceeded water quality guidelines for aquatic life (20 ng/L). Using nontargeted screening, we tentatively identified an additional 24 pharmaceutical and personal care products and 23 pesticides in river water. Effects of river water on ELS fish were observed in both species, but the copper redhorse appeared to be more sensitive. Fish exposed to river water hatched 10.7 (copper redhorse) and 2.4 (river redhorse) cumulative degree days earlier than controls. Copper redhorse survival was significantly lower in river water (73 ± 16%) compared to laboratory water (93 ± 3%), whereas river redhorse survival was similar between treatments (84 ± 6% and 89 ± 4%, respectively). Sequencing of copper redhorse larvae RNA revealed 18 differentially expressed genes (DEGs) following 14 days of exposure to river water. Eight up-regulated DEGs were linked to immune function and injury response, and seven down-regulated DEGs were involved with digestion and nutrient absorption. The present study provided valuable data on the effects of ELS exposure to a real-world mixture of contaminants in two fish species of concern. Environ Toxicol Chem 2022;41:1950-1966. © 2022 SETAC.

Polycyclic aromatic compounds (PACs) in the Canadian environment: Exposure and effects on wildlife.

Polycyclic aromatic compounds (PACs) are ubiquitous in the environment. Wildlife (including fish) are chronically exposed to PACs through air, water, sediment, soil, and/or dietary routes. Exposures are highest near industrial or urban sites, such as aluminum smelters and oil sands mines, or near natural sources such as forest fires. This review assesses the exposure and toxicity of PACs to wildlife, with a focus on the Canadian environment. Most published field studies measured PAC concentrations in tissues of invertebrates, fish, and birds, with fewer studies of amphibians and mammals. In general, PAC concentrations measured in Canadian wildlife tissues were under the benzo[a]pyrene (BaP) guideline for human consumption. Health effects of PAC exposure include embryotoxicity, deformities, cardiotoxicity, DNA damage, changes to DNA methylation, oxidative stress, endocrine disruption, and impaired reproduction. Much of the toxicity of PACs can be attributed to their bioavailability, and the extent to which certain PACs are transformed into more toxic metabolites by cytochrome P450 enzymes. As most mechanistic studies are limited to individual polycyclic aromatic hydrocarbons (PAHs), particularly BaP, research on other PACs and PAC-containing complex mixtures is required to understand the environmental significance of PAC exposure and toxicity. Additional work on responses to PACs in amphibians, reptiles, and semi-aquatic mammals, and development of molecular markers for early detection of biological responses to PACs would provide a stronger biological and ecological justification for regulating PAC emissions to protect Canadian wildlife.

Early life exposure to triphenyl phosphate: Effects on thyroid function, growth, and resting metabolic rate of Japanese quail (Coturnix japonica) chicks.

Triphenyl phosphate (TPHP; CAS # 115-86-6), a commonly used plasticizer and flame retardant, has been reported in wild birds and identified as a potential high-risk chemical. We exposed Japanese quail (Coturnix japonica) by in ovo injection, and once hatched, orally each day for 5 days to safflower oil (controls) or TPHP dissolved in vehicle at low (5 ng TPHP/g), mid (50 ng TPHP/g), or high (100 ng TPHP/g) nominal TPHP doses. The low TPHP dose reflected concentrations in wild bird eggs, with mid and high doses 10x and 20x greater to reflect potential increases in environmental TPHP concentrations in the future. Despite no effects on mRNA expression in thyroid-related genes, TPHP exposure enhanced thyroid gland structure in high TPHP males, but in females, suppressed thyroid gland structure and activity (all TPHP females), and circulating free triiodothyronine (high TPHP females only). Consistent with thyroidal changes, and compared to controls, mid and high TPHP chicks experienced significantly reduced resting metabolic rate (≤13%) and growth (≤53%); mid TPHP males and high TPHP females were significantly smaller. The observed thyroidal effects and suppressed growth and metabolic rate of the quail chicks suggest that TPHP may adversely affect the health of wild birds.

Characterization of the avian aryl hydrocarbon receptor 1 from blood using non-lethal sampling methods.

The amino acid sequence of the aryl hydrocarbon receptor 1 ligand binding domain (AHR1 LBD) is an important determinant of sensitivity to dioxin-like compounds in avian species. We are interested in surveying AHR1 LBD sequences in a large number of birds as a means of identifying species that are particularly sensitive to dioxin-like compounds. Our original method for determining AHR1 LBD genotype used liver tissue and required lethal sampling. Here we present two alternate methods for determining AHR1 LBD genotype which use non-lethal sampling and are more appropriate for ecologically sensitive species. First, we establish that AHR1 LBD mRNA is expressed in avian blood and test a variety of blood collection and handling protocols in order to establish a method that is convenient for field collections. Our findings also identify which types of archival blood samples might be appropriate for AHR1 LBD sequence determination. Second, we present a method for obtaining AHR1 LBD coding sequences from DNA. A DNA-based method is advantageous because DNA can be isolated from many tissue types, is more stable than RNA, and requires less specific sample handling and preservation. This work extends applicability of a genetic screen for dioxin sensitivity to a larger number of species and sample types including endangered species and potentially museum specimens.

Illicit and traditional drug use among ethnic minority adolescents in East London.

OBJECTIVES: To explore ethnic variations in the use of illicit and traditional drugs, and the association of indicators of acculturation with drug use among an ethnically diverse representative sample of early adolescents in East London. STUDY DESIGN: A cross-sectional questionnaire survey. METHODS: Confidential questionnaires were used to assess 2789 male and female pupils in years 7 and 9, aged 11-14 years old, from a representative sample of 28 secondary schools in East London. RESULTS: In total, 10.8% reported having ever tried illicit drugs and 7.3% reported ever using cannabis. Compared with white British adolescents, cannabis use in the previous month was significantly higher amongst black Caribbean adolescents. Lifetime cannabis use was significantly higher amongst black Caribbean and mixed ethnicity young people, but was lower amongst Bangladeshi, Indian and Pakistani adolescents. Living in UK for 5 years or less markedly reduced the risk of lifetime and recent cannabis use when controlled for ethnicity and social class. Glue or solvent use was reported in 3.2% of adolescents, with use significantly higher amongst Bangladeshi young people. Lifetime paan use was reported by 14.1% of the sample, and was almost completely confined to South Asian or mixed ethnicities. CONCLUSIONS: Ethnic differences in illicit drug use were found in the study population, and significant differences were found between ethnic groups often identified as 'black.' Further research is needed in understanding cultural-specific risk and protective factors in different ethnic groups, and the importance of cultural identity in mediating health risk behaviors. The high use of paan and glue/gas/solvents by Bangladeshi young people poses an unappreciated public health problem that may require targeted interventions.

Maternal mortality in England and Wales 1970-1985: an analysis by country of birth.

OBJECTIVE: To determine the risk of maternal mortality in immigrants to England and Wales. DESIGN: Analysis of death registrations, 1970-1985, by country of birth. SETTING: England and Wales. POPULATION: Women dying in England and Wales during pregnancy, childbirth or the puerperium, or dying from malignant tumour of the placenta. MAIN OUTCOME MEASURES: The risk of dying in pregnancy, childbirth or the puerperium, adjusted for age and year of death, and the risk of cause-specific death, adjusted for age, in immigrants compared with women born in England and Wales. RESULTS: Women born in West Africa (relative risk 10.3; 95% CI 8.0-13.2) and the Caribbean (4.6; 3.8-5.7) were at very elevated risk of maternal death and of the main causes of death. Women from Southern Asia (1.6; 1.3-2.0) and "Europe and the USSR' (1.7; 1.2-2.3) were at moderate risk. Adjustment for year of death increased the estimates of risk and women born in the "Rest of the World' and Scotland were at significantly elevated risk. CONCLUSIONS: An increased incidence of obstetric conditions in immigrant groups may account for the elevated risk but it is also possible that differences in care may account for some of the additional risk. The pattern of increased risk does not appear to be explicable by the parity or social class distribution of immigrants as far as data are available on these. Research is required into the aetiology of the differential incidence of obstetric disease. The collection of routine mortality data which include maternal reproductive and social factors would elucidate the significance of such factors to maternal health. Further investigation into possible differences in the process of antenatal care between immigrants and non-immigrants is required, and into whether this affects the risk of maternal mortality.