English

A year and a half ago, with symposia and reverential speeches, the United States and much of the world marked the 50th anniversary of Rachel Carson's book "Silent Spring" and her courageous warnings about environmental threats. Monday -- the 50th anniversary of Carson's death -- is an opportune time to admire her equally courageous silence about matters that could have blunted the book's impact. Most people are surprised to learn that Carson lived only about 18 months after the publication of "Silent Spring." On April 14, 1964, a month shy of her 57th birthday, Carson died in the Maryland suburb of Silver Spring of complications of metastasizing breast cancer. Sadly, she had become a polarizing figure in an increasingly vituperative political atmosphere. Carson did not live to see the positive impact of her message -- prohibition of the agrichemicals aldrin, dieldrin and heptachlor; passage of the National Environmental Policy Act; establishment of the U.S. Environmental Protection Agency; the banning of DDT in the United States in 1972 and the end of its use by much of the world's agriculture within the half-century.

Nicotinic acetylcholine receptors (nAChRs) are ligand‑gated ion channels that mediate fast synaptic transmission in the insect nervous system and are targets of a major group of insecticides, the neonicotinoids. They consist of five subunits arranged around a central ion channel. Since the subunit composition determines the functional and pharmacological properties of the receptor the presence of nAChR families comprising several subunit‑encoding genes provides a molecular basis for broad functional diversity. Analyses of genome sequences have shown that nAChR gene families remain compact in diverse insect species, when compared to their nematode and vertebrate counterparts. Thus, the fruit fly (Drosophila melanogaster), malaria mosquito (Anopheles gambiae), honey bee (Apis mellifera), silk worm (Bombyx mori) and the red flour beetle (Tribolium castaneum) possess 10‑12 nAChR genes while human and the nematode Caenorhabditis elegans have 16 and 29 respectively. Although insect nAChR gene families are amongst the smallest known, receptor diversity can be considerably increased by the posttranscriptional processes alternative splicing and mRNA A‑to‑I editing which can potentially generate protein products which far outnumber the nAChR genes. These two processes can also generate species‑specific subunit isoforms. In addition, each insect possesses at least one highly divergent nAChR subunit which may perform species‑specific functions.

Since 2009 I've been writing about the plight of beleaguered honeybees due to toxic chemicals; over five billion pounds of insecticides -- one third of them are lethal neonicotinoids (neonics) thrust into our biosphere each year. Neonics are a neuro-active insecticide fashioned after nicotine, neonics poison nerves and prevent acetylcholine from enabling neurons to communicate with each other. Over 10 million commercial beehives have died since 2008 -- this is an epic worldwide problem. My colleague Dr Henk Tennekes reported the deadly effects of neonics on both soil organisms and their 'knock-on-effects' causing starvation to meadow birds and their predators Goshawks as well as contaminating waterways for many years thereafter across Western Europe. It seems that his thorough research was blatantly disregarded elsewhere around the globe by feckless government regulatory bodies. An intrepid Dr Christy Morrissey of the University of Saskatchewan set out to investigate just how wide spread the effects of neonics were across the prairies of Western Canada. Eighty to 90 percent of the wetlands she studied were contaminated with these odious poisons, which remain in toxic concentrations within the waterways for years. She too found 'knock-on-effects' in soils extending up the food chain, which reduced populations of many animals. Earthlings are knowingly annihilating the exquisite tapestry of life or Earth's biodiversity. The strength of an ecosystem depends upon the diversity of species. By killing biodiversity, we are killing ourselves; and it's happening very quickly, globally. Dr Morrissey asked some poignant questions about the food we currently produce on our globe: "Is that the cost, no birds? Or having no butterflies? Or having no bees?"

Acetamiprid is a potent and a relatively new neonicotinoid insecticide. Animal studies have indicated that it has a low toxicity to mammals. Despite wide usage, human exposure resulting in toxicity is quite limited, and this is the first report in the English literature about acute acetamiprid poisoning in humans. Case Details. We herein describe two cases of acute poisoning with an insecticide formulation containing acetamiprid for suicidal purposes. Both cases experienced severe nausea and vomiting, muscle weakness, hypothermia, convulsions, and clinical manifestations including tachycardia, hypotension, electrocardiogram changes, hypoxia, and thirst in the case with the higher serum concentration of acetamiprid. The symptoms were partially similar to acute organophosphate intoxication. Supportive treatments for a variety of symptoms were sufficient for recovery, and both individuals were discharged without any complications 2 days after ingestion.

Bees are essential pollinators of many plants in natural ecosystems and agricultural crops alike. In recent years the decline and disappearance of bee species in the wild and the collapse of honey bee colonies have concerned ecologists and apiculturalists, who search for causes and solutions to this problem. Whilst biological factors such as viral diseases, mite and parasite infections are undoubtedly involved, it is also evident that pesticides applied to agricultural crops have a negative impact on bees. Most risk assessments have focused on direct acute exposure of bees to agrochemicals from spray drift. However, the large number of pesticide residues found in pollen and honey demand a thorough evaluation of all residual compounds so as to identify those of highest risk to bees. Using data from recent residue surveys and toxicity of pesticides to honey and bumble bees, a comprehensive evaluation of risks under current exposure conditions is presented here. Standard risk assessments are complemented with new approaches that take into account time-cumulative effects over time, especially with dietary exposures. Whilst overall risks appear to be low, our analysis indicates that residues of pyrethroid and neonicotinoid insecticides pose the highest risk by contact exposure of bees with contaminated pollen. However, the synergism of ergosterol inhibiting fungicides with those two classes of insecticides results in much higher risks in spite of the low prevalence of their combined residues. Risks by ingestion of contaminated pollen and honey are of some concern for systemic insecticides, particularly imidacloprid and thiamethoxam, chlorpyrifos and the mixtures of cyhalothrin and ergosterol inhibiting fungicides. More attention should be paid to specific residue mixtures that may result in synergistic toxicity to bees.

Neonicotinoids are a relatively newer class of insecticide. Used primarily in agriculture, neonicotinoids are also used for flea control in domestic animals. Information on human exposures to neonicotinoids is limited. Neonicotinoid exposures reported to Texas poison centers during 2000–2012 were identified and the distribution by selected factors examined. Of 1,142 total exposures, most products contained imidacloprid (77%) or dinotefuran (17%). The exposures were seasonal with half reported during May–August. The most common routes of exposure were ingestion (51%), dermal (44%), and ocular (11%). The distribution by patient age was 5 years or less (28%), 6–19 years (9%), 20 years or more (61%), and unknown (2%); and 64% of the patients were female. Of all, 97% of the exposures were unintentional and 97% occurred at the patient’s own residence. The management site was on-site (92%), already at/en route to a health care facility (6%), and referred to a health care facility (2%). The medical outcomes included no effect (22%), minor effect (11%), moderate effect (1%), not followed judged nontoxic (14%), not followed minimal effects (46%), unable to follow potentially toxic (1%), and unrelated effect (4%). The most commonly reported adverse clinical effects were ocular irritation (6%), dermal irritation (5%), nausea (3%), vomiting (2%), oral irritation (2%), erythema (2%), and red eye (2%). The most frequently reported treatments were dilution/wash (85%) and food (6%). In summary, these data suggest that the majority of neonicotinoid exposures reported to the poison centers may be managed outside of health care facilities with few clinical effects expected

Aquatic ecosystems are characterized by fluctuating conditions that have direct effects on aquatic communities but also indirect influences such as changing the toxicity of chemicals. Because the effect of food quality on pesticide toxicity has rarely been studied, in the present study Daphnia magna juveniles supplied with 4 different food quality levels were exposed to a range of imidacloprid concentrations for 21 d. Food quality was expressed as carbon:phosphorus ratios of algae Pseudokirchneriella subcapitata (C:P 35, C:P 240, C:P 400, and C:P 1300). Survival, growth rates, and reproduction of D. magna were monitored, and the combined effects of imidacloprid exposure and the phosphorus content of algae were analyzed. A stronger effect on survival was observed at the P-deficient diet (C:P 1300), confirmed by lower 10% effect concentration (EC10) values at days 7, 9, 15, and 21 compared with diets with higher phosphorus contents. Similarly, the growth rate was reduced when D. magna were supplied with algae of low phosphorus content at imidacloprid exposure conditions. The highest reproductive output was observed for D. magna fed the optimal phosphorus diet (C:P 240), both at control and exposed conditions. Poor food quality increased the sensitivity of nontarget species to pesticide exposure, potentially leading to an underestimation of adverse effects on aquatic communities in the field.