English

Organic chemicals can contribute to local and regional losses of freshwater biodiversity and ecosystem services. However, their overall relevance regarding larger spatial scales remains unknown. Here, we present, to our knowledge, the first risk assessment of organic chemicals on the continental scale comprising 4,000 European monitoring sites. Organic chemicals were likely to exert acute lethal and chronic long-term effects on sensitive fish, invertebrate, or algae species in 14% and 42% of the sites, respectively. Of the 223 chemicals monitored, pesticides, tributyltin, polycyclic aromatic hydrocarbons, and brominated flame retardants were the major contributors to the chemical risk. Their presence was related to agricultural and urban areas in the upstream catchment. The risk of potential acute lethal and chronic long-term effects increased with the number of ecotoxicologically relevant chemicals analyzed at each site. As most monitoring programs considered in this study only included a subset of these chemicals, our assessment likely underestimates the actual risk. Increasing chemical risk was associated with deterioration in the quality status of fish and invertebrate communities. Our results clearly indicate that chemical pollution is a large-scale environmental problem and requires far-reaching, holistic mitigation measures to preserve and restore ecosystem health.

Most environmental protection issues concern the often chronic exposure of large populations to low doses of chemical toxins and ionizing radiation. However, measuring the effects of low doses on populations exposed over long time periods is highly problematic. Politically driven opinions often tend to take the place of science. Part of the problem is that epidemiology is a weak tool when the level of exposure is low. High background levels of exposure, genetic diversity, and exposure uncertainties all contribute to “noise” and make dose-response relationships difficult to define. Uncertainty feeds anxiety, leading to polarized politics. This review looks at the promise of molecular technologies for identifying the effects of low doses of radiation and identifies some of the issues involved in defining risk after low-dose exposures. While the main pollutant discussed in this article is ionizing radiation, the analysis could apply equally well to other toxic exposures or to combined radiation and chemical pollutants.

Some of the honeybees were lying on their backs, trembling and twitching. Others were crawling slowly on the ground, unable to fly. Many were motionless, lying dead in piles. Many more had simply disappeared, apparently unable to find their way back to their hives. This was the gruesome scene commercial beekeeper Steve Ellis came upon on the morning of May 7, 2013.
The sight stunned Ellis, who has owned and operated Old Mill Honey Company in Barrett, Minnesota for 35 years. "Normally in the spring, we typically expect bees to build up and get stronger," he recalled. "For a beekeeper to watch his bees be devastated in the springtime — it's like watching a little child get extremely sick and debilitated. It takes a real mental toll on you."
But almost immediately, Ellis discovered the culprit: That morning, a farmer had planted corn in a field directly adjacent to his bee yard, which housed roughly 1,300 hives at the time. He was well aware that most corn seeds are treated with a pesticide called neonicotinoids. And that day, the wind was blowing from the cornfield toward Ellis' bees, the beekeeper wrote in an incident report he sent to the US Environmental Protection Agency. The bees' only sources of food were nearby willow trees, which, Ellis surmised, had become coated with pesticide-contaminated dust. "We took a close look to see how the bees were behaving when they were trying to forage them. It was shocking what we found," Ellis said in a video he took that day documenting the massacre. "Bees literally incapacitated when they come in contact with the flowers."

We have recently been surveying what chemicals the local farmers in East Sussex use each year. Chemicals applied to two fairly typical fields, one with winter oilseed rape, one with winter wheat, in a single growing season (2012/13). I should stress that these are perfectly normal farms; not especially intensive, situated on the edge of the South Downs, an area of gentle hills, hedgerows and wooded valleys. Beautiful, rural England; Constable would have liked it here. But let’s look at it from a bee’s perspective, focussing on the oilseed rape, since this is a crop they will feed on when it flowers: firstly, the crop is sown in late summer with a seed dressing containing the insecticide thiamethoxam. This is a systemic neonicotinoid, with exceedingly high toxicity to bees. We know it is taken up by the plant, and that detectable levels will be in the nectar and pollen gathered by bees in the following spring. In November, despite the supposed protection of the neonicotinoid, the crop is sprayed with another insecticide, the charmingly named Gandalf. Gandalf contains beta-cyfluthrin, a pyrethroid. Pyrethroids are highly toxic to bees and other insects, but there should be no bees about in November so that is probably OK. The following May, when it is flowering, the crop is sprayed with another pyrethroid, alpha-cypermethrin. Less than three weeks later, the crop is blitzed with three more pyrethroids, all mixed together, a real belt-and-braces approach. Why use one when three will do? The crop is still flowering at this point (it was a late year), and would be covered in foraging bumblebees and other pollinators. In between, the crop is also treated with a barrage of herbicides, fungicides, molluscicides and fertilizers – 22 different chemicals in total.

Current bee population declines and colony failures are well documented yet poorly understood and no single
factor has been identified as a leading cause. The evidence is equivocal and puzzling: for instance, many
pathogens and parasites can be found in both failing and surviving colonies and field pesticide exposure is
typically sublethal. Here, we investigate how these results can be due to sublethal stress impairing colony
function. We mathematically modelled stress on individual bees which impairs colony function and found
how positive density dependence can cause multiple dynamic outcomes: some colonies fail while others
thrive. We then exposed bumblebee colonies to sublethal levels of a neonicotinoid pesticide. The dynamics
of colony failure, which we observed, were most accurately described by our model. We argue that our
model can explain the enigmatic aspects of bee colony failures, highlighting an important role for sublethal
stress in colony declines.

The birds’ decline was a stark example of humanity’s lethal effect on wildlife and frightening capacity to exterminate animals, they said. ‘‘It’s terrible,’’ Hunter Bird Observers Club member Chris Herbert said. ‘‘You feel rather helpless that you’re monitoring the decline of a whole group of species in the estuary.’’The Hunter had the most important estuary along the NSW coast for the abundance and diversity of shorebirds, experts say. Birdlife Australia conservation partnerships manager Golo Maurer said the Hunter was ‘‘a key example’’ of threats shorebirds were facing worldwide. Mr Maurer said his organisation had continuously lobbied the federal government about the problem. Mr Herbert said more than 10,000 migratory shorebirds had come to the Hunter estuary every year in the 1970s. ‘‘We can now barely count more than 3000 of them,’’ he said. ‘‘If you project that decline into the future, they’re heading for local extinction in about 20 years.’’