Acute oral toxicity of sodium cyanide in birds

Potential contaminants and hazards in alternative chicken bedding materials and proposed guidance levels: a review

Bedding material or litter is an important requirement of meat chicken production which can influence bird welfare, health, and food safety. A substantial increase in demand and cost of chicken bedding has stimulated interest in alternative bedding sources worldwide. However, risks arising from the use of alternative bedding materials for raising meat chickens are currently unknown. Organic chemicals, elemental, and biological contaminants, as well as physical and management hazards need to be managed in litter to protect the health of chickens and consequently that of human consumers. This requires access to information on the transfer of contaminants from litter to food to inform risk profiles and assessments to guide litter risk management. In this review, contaminants and hazards of known and potential concern in alternative bedding are described and compared with existing standards for feed. The contaminants considered in this review include organic chemical contaminants (e.g., pesticides), elemental contaminants (e.g., arsenic, cadmium, and lead), biological contaminants (phytotoxins, mycotoxins, and microorganisms), physical hazards, and management hazards. Reference is made to scientific literature for acceptable levels of the above contaminants in chicken feed that can be used for guidance by those involved in selecting and using bedding materials.

Behavioral toxicity of sodium cyanide following oral ingestion in rats: Dose-dependent onset, severity, survival, and recovery

Sodium cyanide (NaCN) is a commonly and widely used industrial and laboratory chemical reagent that is highly toxic. Its availability and rapid harmful/lethal effects combine to make cyanide a potential foodborne/waterborne intentional-poisoning hazard. Thus, laboratory studies are needed to understand the dose-dependent progression of toxicity/lethality following ingestion of cyanide-poisoned foods/liquids. We developed an oral-dosing method in which a standard pipette was used to dispense a sodium cyanide solution into the cheek, and the rat then swallowed the solution. Following poisoning (4-128 mg/kg), overt toxic signs were recorded and survival was evaluated periodically up to 30 hours thereafter. Toxic signs for NaCN doses higher than 16 mg/kg progressed quickly from head burial and mastication, to lethargy, convulsions, gasping/respiratory distress, and death. In a follow-on study, trained operant-behavioral performance was assessed immediately following cyanide exposure (4-64 mg/kg) continuously for 5 h and again the following day. Onset of behavioral intoxication (i.e., behavioral suppression) occurred more rapidly and lasted longer as the NaCN dose increased. This oral-consumption method with concomitant operantbehavioral assessment allowed for accurate dosing and quantification of intoxication onset, severity, and recovery, and will also be valuable in characterizing similar outcomes following varying medical countermeasure drugs and doses.

Heap leach cyanide irrigation and risk to wildlife: Ramifications for the international cyanide management code

Exposed cyanide-bearing solutions associated with gold and silver recovery processes in the mining industry pose a risk to wildlife that interact with these solutions. This has been documented with cyanide-bearing tailings storage facilities, however risks associated with heap leach facilities are poorly documented, monitored and audited. Gold and silver leaching heap leach facilities use cyanide, pH-stabilised, at concentrations deemed toxic to wildlife. Their design and management are known to result in exposed cyanide-bearing solutions that are accessible to and present a risk to wildlife. Monitoring of the presence of exposed solutions, wildlife interaction, interpretation of risks and associated wildlife deaths are poorly documented. This paper provides a list of critical monitoring criteria and attempts to predict wildlife guilds most at risk. Understanding the significance of risks to wildlife from exposed cyanide solutions is complex, involving seasonality, relative position of ponding, temporal nature of ponding, solution palatability, environmental conditions, in situ wildlife species inventory and provision of alternative drinking sources for wildlife. Although a number of heap leach operations are certified as complaint with the International Cyanide Management Code (Cyanide Code), these criteria are not considered by auditors nor has systematic monitoring regime data been published. Without systematic monitoring and further knowledge, wildlife deaths on heap leach facilities are likely to remain largely unrecorded. This has ramifications for those operations certified as compliance with the Cyanide Code.

Cyanide poisoning of a Cooper's hawk ( Accipiter cooperii)

A Cooper's hawk ( Accipiter cooperii) was found dead in a ditch leading from a heap leach pad at a gold mine in Nevada. Observations at autopsy included an absence of external lesions, traces of subcutaneous and coronary fat, no food in the upper gastrointestinal tract, and no lesions in the viscera. Cyanide concentrations (µg/g ww) were 5.04 in blood, 3.88 in liver, and 1.79 in brain. No bacteria or viruses were isolated from tissues, and brain cholinesterase activity was within the normal range for a Cooper's hawk.

High levels of activity of bats at gold mining water bodies: implications for compliance with the International Cyanide Management Code

Wildlife and livestock are known to visit and interact with tailings dam and other wastewater impoundments at gold mines. When cyanide concentrations within these water bodies exceed a critical toxicity threshold, significant cyanide-related mortality events can occur in wildlife. Highly mobile taxa such as birds are particularly susceptible to cyanide toxicosis. Nocturnally active bats have similar access to uncovered wastewater impoundments as birds; however, cyanide toxicosis risks to bats remain ambiguous. This study investigated activity of bats in the airspace above two water bodies at an Australian gold mine, to assess the extent to which bats use these water bodies and hence are at potential risk of exposure to cyanide. Bat activity was present on most nights sampled during the 16-month survey period, although it was highly variable across nights and months. Therefore, despite the artificial nature of wastewater impoundments at gold mines, these structures present attractive habitats to bats. As tailings slurry and supernatant pooling within the tailings dam were consistently well below the industry protective concentration limit of 50 mg/L weak acid dissociable (WAD) cyanide, wastewater solutions stored within the tailings dam posed a minimal risk of cyanide toxicosis for wildlife, including bats. This study showed that passively recorded bat echolocation call data provides evidence of the presence and relative activity of bats above water bodies at mine sites. Furthermore, echolocation buzz calls recorded in the airspace directly above water provide indirect evidence of foraging and/or drinking. Both echolocation monitoring and systematic sampling of cyanide concentration in open wastewater impoundments can be incorporated into a gold mine risk-assessment model in order to evaluate the risk of bat exposure to cyanide. In relation to risk minimisation management practices, the most effective mechanism for preventing cyanide toxicosis to wildlife, including bats, is capping the concentration of cyanide in tailings discharged to open impoundments at 50 mg/L WAD.

Assessment of toxicity and potential risk of the anticoagulant rodenticide diphacinone using Eastern screech-owls (Megascops asio)

In the United States, new regulatory restrictions have been placed on the use of some second-generation anticoagulant rodenticides. This action may be offset by expanded use of first-generation compounds (e.g., diphacinone; DPN). Single-day acute oral exposure of adult Eastern screech-owls (Megascops asio) to DPN evoked overt signs of intoxication, coagulopathy, histopathological lesions (e.g., hemorrhage, hepatocellular vacuolation), and/or lethality at doses as low as 130 mg/kg body weight, although there was no dose-response relation. However, this single-day exposure protocol does not mimic the multiple-day field exposures required to cause mortality in rodent pest species and non-target birds and mammals. In 7-day feeding trials, similar toxic effects were observed in owls fed diets containing 2.15, 9.55 or 22.6 ppm DPN, but at a small fraction (<5%) of the acute oral dose. In the dietary trial, the average lowest-observed-adverse-effect-level for prolonged clotting time was 1.68 mg DPN/kg owl/week (0.24 mg/kg owl/day; 0.049 mg/owl/day) and the lowest lethal dose was 5.75 mg DPN/kg owl/week (0.82 mg/kg owl/day). In this feeding trial, DPN concentration in liver ranged from 0.473 to 2.21 μg/g wet weight, and was directly related to the daily and cumulative dose consumed by each owl. A probabilistic risk assessment indicated that daily exposure to as little as 3-5 g of liver from DPN-poisoned rodents for 7 days could result in prolonged clotting time in the endangered Hawaiian short-eared owl (Asio flammeus sandwichensis) and Hawaiian hawk (Buteo solitarius), and daily exposure to greater quantities (9-13 g of liver) could result in low-level mortality. These findings can assist natural resource managers in weighing the costs and benefits of anticoagulant rodenticide use in pest control and eradication programs.

Feeding Behavior-Related Toxicity due to Nandina domestica in Cedar Waxwings (Bombycilla cedrorum)

Dozens of Cedar Waxwings were found dead in Thomas County, Georgia, USA, in April 2009. Five of these were examined grossly and microscopically. Grossly, all the examined birds had pulmonary, mediastinal, and tracheal hemorrhages. Microscopically, several tissues and organs were diffusely congested and hemorrhagic. Congestion and hemorrhage were marked in the lungs. Intact and partly digested berries of Nandina domestica Thunb. were the only ingesta found in the gastrointestinal tract of these birds. Due to their voracious feeding behavior, the birds had eaten toxic doses of N. domestica berries. N. domestica contains cyanide and is one of the few berries readily available at this time of the year in the region. The gross and microscopic findings are consistent with lesions associated with cyanide toxicity. This paper for the first time documents toxicity associated with N. domestica in Cedar Waxwings.

Factors influencing the risk of wildlife cyanide poisoning on a tailings storage facility in the Eastern Goldfields of Western Australia

Patterns of wildlife visitation and interaction with cyanide-bearing tailings slurry and solutions at the Fimiston tailings storage facility (TSF) have been reported in a previously published ecological study. The above-mentioned findings are extended in this paper by the examination of additional wildlife survey data, along with process water chemistry data collected during the same study period. Analysis of the combined results revealed that the primary wildlife protective mechanism in operation was effective management of tailings cyanide concentration. Nevertheless, tailings discharge concentration exceeded the industry standard wildlife protective limit of 50mg/L weak acid dissociable (WAD) cyanide episodically during the study period. Wildlife that interacted with habitats close to the spigot outlet during brief periods of increased discharge concentration were likely to have been exposed to bioavailable cyanide at concentrations greater than the industry standard protective limit. However, no wildlife deaths were recorded. These results appear to support the hypothesis that hypersalinity of process solutions (unique to the Kalgoorlie district of Western Australia) and a lack of aquatic food resources represent secondary protective mechanisms that operated to prevent cyanide-related wildlife mortality during the project. The proposed protective mechanisms are discussed in the context of their potential application as proactive management procedures to minimise wildlife exposure to cyanide.

Improved derivatisation methods for the determination of free cyanide and cyanate in mine effluent

Generally, the level of cyanide in waste effluents is too high to be discharged into the environment. Consequently, treatment regimes are necessary in order to protect the environment. However, the cost of most of the treatment methods is expensive and not sensitive enough and, therefore, cannot always be justified. In this research, cyanide speciation products, free cyanide (CN(-)) and cyanate (CNO(-)) were determined by highly sensitive derivatisation methods followed by spectrometric analysis. Spectral scans were carried out for pure and environmental samples derivatives in order to evaluate the possibility of interfering species. For CN(-) a linear range from 0.01 to 80.0mg/L was determined. In the case of CNO(-), the linear range was between 0.02 and 80.0mg/L. The detection limits were 0.05 and 0.20mg/L for CN(-) and CNO(-), respectively. These values are in good agreement with those reported in literature. The concentration ranges of the speciation products in environmental samples were 0.70-52.0mg/L and 0.50-76.0mg/L for CN(-) and CNO(-), respectively. These values were well above their acute toxicity levels. Increase in cyanate levels in the effluent with time was clearly observed while the concentration of cyanide decreased. This was attributed to the oxidation of CN(-) to CNO(-).

The protection of wildlife from mortality: hypothesis and results for risk assessment

Wildlife deaths associated with cyanide-bearing tailings dams are a significant environmental issue that has affected the gold mining industries for many years and still characterized by little knowledge about how to measure, monitoring, reduce or eliminate those deaths. The purpose of this paper is statistically to determine: the potential for establishing causal relations between exposure to cyanide (in its most common species relevant to tailings) and response (measured by death counts), to develop a protocol of data analysis, the understanding of the significance of data gaps, and the effect of likely risk management interventions to achieve the goals of the International Cyanide Management Code (ICMC); [ICMC The International Cyanide Management Institute. International cyanide management code, the international cyanide management institute 2005, www.cyanidecode.org.]. However, operator's certification under the ICMC is difficult because of the limited data and potentially serious under-estimation of the death counts. This is due to observational skill and monitoring frequency, the small size of the carcasses, large extent of tailings facilities, carcasses loss by; entombment in tailings, sink, or taken by scavenging wildlife. This (1st order or bounding) assessment results focus on bird-deaths, which appear to be most frequent at sites where elevated cyanide concentrations are found. Those results indicate that the empirical causal associations we generate support the hypotheses that: This paper also develops the basis for a complete risk assessment study to be based on additional data gathering activities and detailed statistical analyses. These two activities, combined with a risk management plan also being developed, will provide a tool for compliance with the ICMC.

A critical review of the effects of gold cyanide-bearing tailings solutions on wildlife

Wildlife deaths associated with cyanide-bearing mine waste solutions have plagued the gold mining industries for many years, yet there is little published data showing the relationship between wildlife mortality and cyanide toxicity. A gap of knowledge exists in monitoring, understanding the causal relationships and managing risks to wildlife from cyanide-bearing waste solutions and tailings. There is a need for the gold industry to address this issue and to meet the International Cyanide Management Code (ICMC) guidelines. The perceived extent of the issue varies, with one study finding the issue inadequately monitored and wildlife deaths grossly underestimated. In Nevada, USA during 1990 and 1991, 9512 carcasses were reported of over 100 species, although there was underestimation due to reporting being voluntary. Of these, birds comprised 80-91% of vertebrate carcasses reported annually. At Northparkes, Australia in 1995, it was initially estimated that 100 bird carcasses were present by mine staff following a tailings incident; when a thorough count was conducted, 1583 bird carcasses were recorded. Eventually, 2700 bird deaths were documented over a four-month period. It is identified that avian deaths are usually undetected and significantly underestimated, leading to a perception that a risk does not exist. Few guidelines and information are available to manage the risks of cyanide to wildlife, although detoxification, habitat modification and denying wildlife access have been used effectively. Hazing techniques have proven ineffective. Apparently no literature exists that documents accurate wildlife monitoring protocols on potentially toxic cyanide-bearing mine waste solutions or any understanding on the analysis of any derived dataset. This places the onus on mining operations to document that no risk to wildlife exists. Cyanide-bearing tailings storage facilities are environmental control structures to contain tailings, a standard practice in the mining industry. Cyanide concentrations below 50 mg/L weak-acid-dissociable (WAD) are deemed safe to wildlife but are considered an interim benchmark for discharge into tailings storage facilities (TSFs). Cyanide is a fast acting poison, and its toxicity is related to the types of cyanide complexes that are present. Cyanide in biota binds to iron, copper and sulfur-containing enzymes and proteins required for oxygen transportation to cells. The accurate determination of cyanide concentrations in the field is difficult to achieve due to sampling techniques and analytical error associated with loss and interferences following collection. The main WAD cyanide complexes in gold mine tailings are stable in the TSF environment but can release cyanide ions under varying environmental conditions including ingestion and absorption by wildlife. Therefore distinction between free, WAD and total cyanide forms in tailings water for regulatory purposes is justified. From an environmental perspective, there is a distinction between ore bodies on the basis of their copper content. For example, wildlife deaths are more likely to occur at mines possessing copper-gold ores due to the formation of copper-cyanide complexes which is toxic to birds and bats. The formation of copper-cyanide complex occurs preferentially to gold cyanide complex indicating the relative importance of economic vs. environmental considerations in the tailings water. Management of cyanide to a perceived threshold has inherent risks since cyanide has a steep toxicity response curve; is difficult to accurately measure in the field; and is likely to vary due to variable copper content of ore bodies and ore blending. Consequently, wildlife interaction needs to be limited to further reduce the risks. A gap in knowledge exists to design or manage cyanide-bearing mine waste solutions to render such facilities unattractive to at-risk wildlife species. This gap may be overcome by understanding the wildlife behaviour and habitat usage of cyanide-bearing solutions.

Cyanide hazards to plants and animals from gold mining and related water issues

Cyanide extraction of gold through milling of high-grade ores and heap leaching of low-grade ores requires cycling of millions of liters of alkaline water containing high concentrations of potentially toxic sodium cyanide (NaCN), free cyanide, and metal-cyanide complexes. Some milling operations result in tailings ponds of 150 ha and larger. Heap leach operations that spray or drip cyanide onto the flattened top of the ore heap require solution processing ponds of about 1 ha in surface area. Puddles of various sizes may occur on the top of heaps, where the highest concentrations of NaCN are found. Solution recovery channels are usually constructed at the base of leach heaps, some of which may be exposed. All these cyanide-containing water bodies are hazardous to wildlife, especially migratory waterfowl and bats, if not properly managed. Accidental spills of cyanide solutions into rivers and streams have produced massive kills of fish and other aquatic biota. Freshwater fish are the most cyanide-sensitive group of aquatic organisms tested, with high mortality documented at free cyanide concentrations >20 microg/L and adverse effects on swimming and reproduction at >5 microg/L. Exclusion from cyanide solutions or reductions of cyanide concentrations to nontoxic levels are the only certain methods of protecting terrestrial vertebrate wildlife from cyanide poisoning; a variety of exclusion/cyanide reduction techniques are presented and discussed. Additional research is recommended on (1) effects of low-level, long-term, cyanide intoxication in birds and mammals by oral and inhalation routes in the vicinity of high cyanide concentrations; (2) long-term effects of low concentrations of cyanide on aquatic biota; (3) adaptive resistance to cyanide; and (4) usefulness of various biochemical indicators of cyanide poisoning. To prevent flooding in mine open pits, and to enable earth moving on a large scale, it is often necessary to withdraw groundwater and use it for irrigation, discharge it to rapid infiltration basins, or, in some cases, discharge it to surface waters. Surface waters are diverted around surface mining operations. Adverse effects of groundwater drawdown include formation of sinkholes within 5 km of groundwater drawdown; reduced stream flows with reduced quantities of wate available for irrigation, stock watering, and domestic, mining and milling, and municipal uses; reduction or loss of vegetation cover for wildlife, with reduced carrying capacity for terrestrial wildlife; loss of aquatic habitat for native fishes and their prey; and disruption of Native American cultural traditions. Surface discharge of excess mine dewatering water and other waters to main waterways may contain excess quantities of arsenic, total dissolved solids, boron, copper, fluoride, and zinc. When mining operations cease, and the water pumps are dismantled, these large open pits may slowly fill with water, forming lakes. The water quality of pit lakes may present a variety of pressing environmental problems.

Rhodanese (thiosulfate: cyanide sulfurtransferase) in the digestive tract of chicken at different stages of development

This study was undertaken to investigate the relationships between stage of embryonic development and early posthatch growth and the level of rhodanese (thiosulfate:cyanide sulfurtransferase) activity in different regions of the digestive tract and liver of chickens. The embryos were studied at 14, 17, and 20 d and chickens were 1, 2, and 3 wk old. All tissues studied contained rhodanese. The highest specific activity of rhodanese was present in the liver followed by the proventriculus (P < 0.05). The lowest level was in the esophagus. The level of rhodanese was found to increase with age in the proventriculus and duodenum. The highest rhodanese activity in 3-wk-old chickens was in the proventriculus followed by the liver. These results are discussed in terms of the role of different sections of the digestive tract of the chicken in cyanide metabolism.

Cyanide and migratory birds at gold mines in Nevada, USA

: Since the mid-1980s, cyanide in heap leach solutions and mill tailings ponds at gold mines in Nevada has killed a large but incompletely documented number of wildlife (>9,500 individuals, primarily migratory birds). This field investigation documents the availability of cyanide at a variety of 'typical' Nevada gold mines during 1990 and 1991, describes wildlife reactions to cyanide solutions, and discusses procedures for eliminating wildlife loss from cyanide poisoning. Substantial progress has been made to reduce wildlife loss. About half of the mill tailings ponds (some up to 150 ha) in Nevada have been chemically treated to reduce cyanide concentrations (the number needing treatment is uncertain) and many of the smaller heap leach solution ponds and channels are now covered with netting to exclude birds and most mammals. The discovery of a cyanide gradient in mill tailings ponds (concentration usually 2-3 times higher at the inflow point than at reclaim point) provides new insight into wildlife responses (mortality) observed in different portions of the ponds. Finding dead birds on the tops of ore heaps and associated with solution puddling is a new problem, but management procedures for eliminating this source of mortality are available. A safe threshold concentration of cyanide to eliminate wildlife loss could not be determined from the field data and initial laboratory studies. New analytical methods may be required to assess further the wildlife hazard of cyanide in mining solutions.

Alternative sulphur donors for detoxification of cyanide in the chicken

1. Urinary excretion of thiocyanate by hens after dosage with cyanide was studied over 3 hr periods during which various sulphur sources were infused. 2. With 20 mumoles cyanide, endogenous sulphur supplies appeared to be almost sufficient. 3. With 45 mumoles cyanide, thiocyanate excretion was doubled with 90 mumoles of sulphur donor. Higher doses of mercaptopyruvate were also effective but not rhodanese substrates (thiosulphate or methanethiosulphonate): they interfered with thiocyanate excretion and may also have suppressed its formation. 4. Mercaptopyruvate and rhodanese substrates also differed in their effects on blood cyanide concentration and on the excretion of isotope from radiolabelled cyanide.