Environmental exposures are one of the greatest threats to human health, yet we lack tools to answer simple questions about our exposures: what are our personal exposure profiles and how do they change overtime (external exposome), how toxic are these chemicals, and what are the sources of these exposures? To capture variation in personal exposures to airborne chemicals in the gas and particulate phases and identify exposures which pose the greatest health risk, wearable exposure monitors can be deployed. In this study, we deployed passive air sampler wristbands with 84 healthy participants (aged 60–69 years) as part of the Biomarkers for Air Pollutants Exposure (China BAPE) study. Participants wore the wristband samplers for 3 days each month for five consecutive months. Passive samplers were analyzed using a novel gas chromatography high resolution mass spectrometry data-processing workflow to overcome the bottleneck of processing large datasets and improve confidence in the resulting identified features. The toxicity of chemicals observed frequently in personal exposures were predicted to identify exposures of potential concern via inhalation route or other routes of airborne contaminant exposure. Three exposures were highlighted based on elevated toxicity: dichlorvos from insecticides (mosquito/malaria control), naphthalene partly from mothballs, and 183 polyaromatic hydrocarbons from multiple sources. Other exposures explored in this study are linked to diet and personal care products, cigarette smoke, sunscreen, and antimicrobial soaps. We highlight the potential for this workflow employing wearable passive samplers for prioritizing chemicals of concern at both the community and individual level, and characterizing sources of exposures for follow up interventions.

Pyrethroid-resistant Hyalella azteca with voltage-gated sodium channel mutations have been identified at multiple locations throughout California. In December 2013, H. azteca were collected from Mosher Slough in Stockton, CA, USA, a site with reported pyrethroid (primarily bifenthrin and cyfluthrin) sediment concentrations approximately twice the 10-d LC50 for laboratory-cultured H. azteca. These H. azteca were shipped to Southern Illinois University Carbondale and have been maintained in pyrethroid-free culture since collection. Even after 22 months in culture, resistant animals had approximately 53 times higher tolerance to permethrin than non-resistant laboratory-cultured H. azteca. Resistant animals held in culture also lacked the wild-type allele at the L925 locus, and had non-synonymous substitutions that resulted in either a leucine-isoleucine or leucine-valine substitution. Additionally, animals collected from the same site nearly three years later were again resistant to the pyrethroid permethrin. When resistant animals were compared to non-resistant animals, they showed lower reproductive capacity, lower upper thermal tolerance, and the data suggested greater sensitivity to, 4, 4′-dichlorodiphenyltrichloroethane (DDT), copper (II) sulfate, and sodium chloride. Further testing of the greater heat and sodium chloride sensitivity of the resistant animals showed these effects to be unrelated to clade association. Fitness costs associated with resistance to pyrethroids are well documented in pest species (including mosquitoes, peach-potato aphids, and codling moths) and we believe that H. azteca collected from Mosher Slough also have fitness costs associated with the developed resistance.

The present study was undertaken to assess the impact of a candidate mosquito larvicide, spinosad (8, 17 and 33 μg L−1) on a field population of Daphnia magna under natural variations of water temperature and salinity, using Bti (0.16 and 0.50 μL L-1) as the reference larvicide. Microcosms (125 L) were placed in a shallow temporary marsh where D. magna was naturally present. The peak of salinity observed during the 21-day observation period may have been partly responsible for the decrease of daphnid population density in all the microcosms. It is also probably responsible for the absence of recovery in the microcosms treated with spinosad which caused a sharp decrease of D. magna abundance within the first two days following treatment whereas Bti had no effect. These results suggest that it may be difficult for a field population of daphnids to cope simultaneously with natural (water salinity and temperature) and anthropogenic (larvicides) stressors.

Despite the increased attention for temporal aspects of stressor interactions and for effects of warming in ecotoxicological studies, we lack knowledge on how different exposure durations to warming may affect pesticide sensitivity. We tested how three types of exposure duration to 4 °C warming (acute, developmental and transgenerational exposure to 24 °C vs 20 °C) shape the effect of the pesticide chlorpyrifos on two ecologically relevant fitness-related traits of mosquito larvae: heat tolerance and antipredator behaviour. Transgenerational (from the parental generation) and developmental (from the egg stage) warming appeared energetically more stressful than acute warming (from the final instar), because (i) only the latter resulted in an adaptive increase of heat tolerance, and (ii) especially developmental and transgenerational warming reduced the diving responsiveness and diving time. Exposure to chlorpyrifos decreased the heat tolerance, diving responsiveness and diving time. The impact of chlorpyrifos was lower at 24 °C than at 20 °C indicating that the expected increase in toxicity at 24 °C was overruled by the observed increase in pesticide degradation. Notably, although our results suggest that transgenerational warming was energetically more stressful, it did reduce the chlorpyrifos-induced negative effects at 24 °C on heat tolerance and the alarm escape response compared to acute warming. Our results provide important evidence that the exposure duration to warming may determine the impact of a pesticide under warming, thereby identifying a novel temporal aspect of stressor interactions in risk assessment.

In 2014, as an attempt to address the Zika health crisis by controlling the mosquito population, Brazil took the unprecedented action of applying a chemical larvicide, pyriproxyfen, to drinking water sources. The World Health Organization has established an acceptable daily intake of pyriproxyfen to be 100 μg per kg of body weight per day, but studies have demonstrated that at elevated doses (>5000 mg/kg), there are adverse effects in mice, rats and dogs. To better understand the potential developmental toxicity of pyriproxyfen, we utilized the embryonic zebrafish. Our results demonstrate that the concentration resulting in 50% of animals presenting adverse morphological effects (EC50), including craniofacial defects, was 5.2 μM for daily renewal exposure, and above this concentration, adverse behavioral effects were also observed in animals that followed a static exposure regimen. Thus, zebrafish data suggest that the developmental toxicity of pyriproxyfen may not be limited to insects.

Air pollution is among the top risk faced by people around the world, and therefore combating it is among the top priorities. It begins with identifying the sources that contribute the most to local air pollution to prioritize their control. There are advanced methods for source identification and apportionment, but such methods are not available in many low-income countries and not everywhere in all high-income countries. We propose a simplified method by using source the signatures to help obtain information about the local source contribution if no other methods are available. Using low-cost monitors, particle mass (PM₂.₅) and carbon monoxide (CO) concentrations were measured and the ratio of CO/PM₂.₅ was determined. We investigated outdoor and indoor sources, including vehicular exhaust, combustion of biomass, incense and mosquito coil burning, and cigarette smoking. The results show that the ratios differed significantly between certain pollutant sources. Compressed natural gas (CNG) engines have a high ratio (mean value of 972 ± 419), which is attributed to relatively low PM₂.₅ emissions, while ship emissions and cigarette smoke recorded a relatively low ratio. Most traffic emissions recorded higher ratios than those of bushfire emissions, and ratios of most outdoor pollutant sources were much higher than those of indoor pollutant sources. There is a clear trend for ratios to decrease from high to low for CNG, petrol, diesel for buses, and fuel for ships. Our results suggest that the ratio of CO/PM₂.₅ can be used as an effective method to identify pollution sources.

A hydrodynamic model is applied to a domain encompassing Mosquito Lagoon and a segment of north Indian River Lagoon on the east coast of Florida with the goals of (1) describing the hydrodynamic regime of the area according to existing conditions and (2) to determine the flushing rates of the system after introducing a hypothetical pollutant (numerical dye tracer). Results from the 1-year simulation agree with observations and show that the Mosquito Lagoon (ML) and North Indian River Lagoon (NIRL) are dominated by the nontidal (low frequency) water level oscillations except at the northernmost part of the ML where the influence of tidal renewal dominates. The global tracer application results reveal that only the two northernmost segments of Mosquito Lagoon (ML-ac and ML-df) reach 50% of tracer concentrations (R50) within the year of simulation (day 19 and day 176 respectively). The five (discrete) segments tracer study resulted in lower R50 values and the hypothetical pollutant is removed (flushed) from each of the segments within the year and with an averaged renewal time value for the Mosquito Lagoon basin of 98 days. Observed throughout the simulation period is the interaction across the different segments and a predominantly two-layered water mass exchange through the Haulover Canal. Most significant is that the resulting renewal times (R50) indicate the existence of three dynamically distinct sections within Mosquito Lagoon. These findings aid in the identification of poorly flushed zones and serve as a baseline for the duration and possible propagation of detrimental conditions such as a harmful algal bloom (HAB) event or a contaminant spill.

This paper explores the main factors for mosquito-borne transmission of the Zika virus by focusing on environmental, anthropogenic, and social risks. A literature review was conducted bringing together related information from this genre of research from peer-reviewed publications. It was observed that environmental conditions, especially precipitation, humidity, and temperature, played a role in the transmission. Furthermore, anthropogenic factors including sanitation, urbanization, and environmental pollution promote the transmission by affecting the mosquito density. In addition, socioeconomic factors such as poverty as well as social inequality and low-quality housing have also an impact since these are social factors that limit access to certain facilities or infrastructure which, in turn, promote transmission when absent (e.g., piped water and screened windows). Finally, the paper presents short-, mid-, and long-term preventative solutions together with future perspectives. This is the first review exploring the effects of anthropogenic aspects on Zika transmission with a special emphasis in Brazil.

The adverse effects of air emissions from animal feeding operations (AFOs) on public health, environment, and quality-of-life have been well-documented. Regulations or lawsuits may force AFOs to reduce their air emissions. Since livestock barn particulate matter (PM) has relatively high particle density and diameter and many gasses adsorb onto PM, its filtration might reduce air emissions. A porous windbreak wall that imposes acceptable backpressure (< 12.5 Pa) and covers the fan could be a promising option. Seventy-two different porous windbreak wall scenarios were modeled to compare their backpressure on the fan as well as average airspeed over the ground. These scenarios were combinations of shape (box, chamfered, curved), size (lengths of 2, 2.5, and 3 fan diameters), presence or absence of an opening (opened and closed), screen porosity (mosquito screen or clean screen, SunBlocker 70% or clogged screen), and fan angle and height. Backpressure and airspeed decreased with increasing windbreak wall length. Generally, the box-shaped windbreak wall had lower backpressure and airspeeds than the other shapes. The increased backpressure with clogged screen even at two fan diameters (2d) was acceptable. The tilted fan commonly used in poultry houses had higher backpressure and airspeed over the ground than the non-tilted fan used in swine houses due to the former’s lower surface area and tilt towards the ground. Overall, taking into account cost considerations and footprint size (for retrofittability), despite its higher airspeed over the ground (vs. larger footprints) and modest reduction in airflow rate, the 2d, open box model seems the most promising option.

Malathion is an organophosphate insecticide registered for use in cities throughout North America to control adult mosquitoes. The objective of this study was to determine the impact of urban malathion applications on the levels of malathion detected in bulk deposition. In 2010, malathion was applied by the City of Winnipeg’s Insect Control Branch for a total amount of 6632 kg in the city, as well as by the general public in relatively small amounts. In 2011, no malathion was applied by the city. Malathion was detected in 41 % of the samples in 2010 with deposition rates ranging from 0.5 to 107.7 μg/m²/week. Only 9 % of the samples contained malathion in 2011 with deposition rates always being <0.4 μg/m²/week. Between 6 and 25 % of the samples in 2010 exceeded the toxicological threshold levels of malathion to a range of freshwater amphipods, water fleas, and stoneflies, including Daphnia magna which is a bioindicator of good environmental health. The weekly maximum malathion concentration detected in this study (5.2 μg/L for a week in June 2010) was at least 26 times greater than the maximum concentration of malathion reported in other atmospheric deposition studies. For the two insect management areas (7.4 and 37.6 km²) where the bulk deposition samplers had been placed, calculations suggested that between 1.2 and 5.1 % of the malathion applied by the city became bulk deposition. Percutaneous absorption by humans of malathion in rainfall is unknown.