Environmental contamination by mercury in Iraq

Part III Environmental contamination by mercury in Iraq A. JERNELOV a Following the outbreak of organomercury poisoning in Iraq, an investiga- tion was carried out during the spring and summer of 1972 to evaluate environmental contamination by organomercury. Analyses were performed on fish of several species (not typical predators) and on a few specimens of aquatic birds (not fish-eating). Most fish samples contained concentrations in muscle ranging from 0.01 to 0.15 mg/kg. These concentrations are within the range found in tropical rivers. Higher figures, 0.3-0.5 mg/kg, were found downstream from a caustic soda plant south of Baghdad. A few cases of very high mercury concentra- tions (25-30 mg/kg) were reported from an area where fish kills had occurred. Aquatic birds (ducks and waders) contained low concentrations of mercury (900-2750 ng/g). Tail feathers of seed-eating birds were found to contain 13 500-21 000 ng/g of mercury, which is about 10 times higher than values reported from Ethiopia and within the range found in Sweden and Canada. Insect-eating birds contained 1850-5200 ng/g, which is thought to be slightly elevated. Extremely high concentrations of mercury were found in muscle tissue of dead seed-eating birds (15 000-40 000 ng/g), while feathers contained similar concentrations (9000-52 000 ng/g). These extremely high concentrations were found only in the vicinity of storehouses where treated seed was kept. No birds of prey could be caught and analysed. INTRODUCTION During the spring and early summer of 1972 a study was carried out in Iraq to evaluate environmental contamination by mercury following the outbreak of mercury poisoning, and to estimate related health hazards to man from continued exposure through food-chains. Samples of wild life, such as small mammals, reptiles, birds, and fish, were collected from the provinces of Anbar, Baghdad, Babylon, Diyala, Kirkuk and Nineveh. A total of just under 200 samples were taken, in addition to those for a study of mercury leakage from storehouses. Some were analysed in Baghdad but the majority were sent to the Swedish Water and Air Pollution Research Laboratory in Stockholm. While the number of samples taken could not cover the entire country and all biological life, the results give some idea of the degree of general contamination, particular atten- tion being paid to the two main bodies of water - the Euphrates And Tigris Rivers. a Swedish Water and Air Pollution Research Laboratory, Stockholm, Sweden. - 115 - 116 AQUATIC ENVIRONMENT Specimens of several species of fish and a few samples of aquatic birds were analysed for total mercury. With a few exceptions - discussed below - the fish samples contained low concentrations of mercury in flesh (0.01-0.15 mg/kg). These concentrations are below the level considered as background in northern Europe and North America, and within the range found in tropical rivers such as the Congo and the Amazon.1 Higher mercury concentrations of 0.3-0.5 mg/kg were found in fish from the River Tigris downstream from a caustic soda factory. These levels although clearly raised, are still below the safety levels currently in force in Canada, the USA and Sweden. From some parts of the country, fish kills were reported following the dumping of treated seed in rivers and irrigation canals. A few samples of fish analysed within the framework of the food control programme were found to contain very high concentrations of mercury (25-30 mg/kg). These were described as "dead fish" (translated from the Arabic on labels by a technician) and originated from one of the districts where fish kills had been reported. The concentrations observed are within the range at which acute toxic effects of methylmercury in fish have been reported. Control analyses of fish caught alive from the same area showed no increased values (0.05-0.1 mg/kg). Aquatic birds, both ducks and waders, contained low concentrations of mercury, 900-2750 ng/g, which levels are similar to those found in Swedish migratory birds after they have wintered in Ethiopia.a TERRESTRIAL ENVIRONMENT Seed-eating birds and small mammals like hedgehogs from the 6 provinces mentioned above were found to contain mercury levels similar to those observed in Canada, northern YSA and Scandinavia by Hamilton & Rissner (personal communication) and by Westermark et al. The levels, 13.5-21.0 pg/g, found in tail feathers from seed-eating birds were almost 10 times higher than those reported from Ethiopia. The few insect-eating birds that were caught also contained raised mercury levels (1.8-5.2 pag/g).I The mercury levels observed in land birds were typical of those in a country with a generally elevated background from industrial and/or agricultural use of mercury, as in Canada and Sweden. A number of exceptionally high mercury levels in birds, rats, and mice were found in the neighbourhood of government storehouses to which treated grain was returned by the farmers after the outbreak of poisoning. Here dead birds and rodents were found with levels of 15.0-40.0 pg/g in muscle and 9.0-52.0 pg/g in feathers, and living specimens with very high concentrations were caught. Attempts to sample birds of prey on top of the terrestrial food-chain, such as eagles, falcons and hawks, were unsuccessful. No members of these bird families were even observed. Iraqi zoologists confirmed the rarity of these birds and stated that they had been less frequently seen during the last 15 to 20 years, possibly owing to the use of mercurials or of other groups of insecticides. STUDY ON "LEAKAGE" OF MERCURY FROM STOREHOUSES A small study was performed around 3 storehouses to illustrate the possible "leakage" of mercury to the environment through seed-eating birds. In each of 3 circles with radii of approximately 0-200 m, 2 km and 5 km, 5-10 grey sparrows were caught. a -WESTERMARK, T. ET AL. Effects of the change from alkyl mercury compounds to alkoxy- alkyl mercury compounds for seed-dressing in Swedish agriculture. Ambio, 1975 (in press). The bird population staying within 200 m of the storehouses contained 70-1000 times the mercury level generally recorded in seed-eating birds in Iraq. At a distance of 2 km only 3 out of 26 birds had levels over twice the average, and at a distance of 5 km no bird was found to contain mercury levels significantly above the regional background. It thus appears that seed-eating birds, and probably rodents also, had a tendency to remain close to a food source, once found, and thus literally ate themselves to death. The accumulation of mercury in seed-eating organisms in and around storehouses thus does not seem to cause any large scale spread of mercury into natural foodwebs and chains. Besides seed-eaters, cats, which eat dead and dying birds and rodents, were the only group of animals living in the vicinity of storehouses found to be clearly affected. The signs of poisoning in these animals were the same as those recorded in Japan and in experi- mental situations in Sweden. The forms of mercury found in the analyses are as follows: ACKNOWLEDGENENTS The author is indebted to Dr Hamilton and Dr Rissner and to Iraqi colleagues for their valuable work and collaboration. RESUME CONTAMINATION DE L 'ENVIRONNEMENT PAR LES COMPOSES MERCURIELS EN IRAK A la suite de 1'Episode d'intoxication par les compos6s organomercuriels en Irak, une enqugte a 6t6 faite au cours du printemps et de 1'ete de 1,72 pour 6valuer la contamination de l'environnement due a ces composes. Des analyses ont 6t6 effectu6es sur plusieurs especes de poisson (non predateurs typiques) et sur quelques specimens d'oiseaux aquatiques (non ichtyophages). La plupart des 6chantillons de poisson pr6sentaient des concentrations musculaires allant de 0,01 A 0,15 mg/kg, correspondant A celles quiontWtE observees dans les cours d'eau tropicaux. Des valeurs plus dlev6es, de 0,3 A 0,5 mg/kg, ont W observees en aval d'une usine de soude caustique au sud de Bagdad. Quelques concentrations de mercure tres 6lev4es (25-30 mg/kg) ont 4t4 signal4es dans une region oiu des poissons avaient peri. Chez les oiseaux aquatiques (canards et echassiers) les concentrations de mercure 6taient faibles Specimen Form of mercury Fish Predominantly methylmercury Bird feathers Predominantly methylmercury Wheat Methylmercury with a varying degree of inorganic impurities Barley Predominantly methoxypropylmercury. Varying amounts of phenylmercury up to 40%. Traces of methylmercury and ethylmercury. 118 (900-2750 ng/g). Les plumes de la queue d'oiseaux granivores contenaient de 13 500 A 21 000 ng de mercure par g, soit des valeurs dix fois sup6rieures a celles signales en Ethiopie et correspondant aux valeurs observees en Suede et au Canada. Sur des oiseaux insectivores, on a trouve des concentrations de 1850-5200 ng/g, valeurs qui paraissent 16g6rement augment6es. Des concentrations extremement 4levees de mercure ont 4te trouv4es dans les tissus musculaires d'oiseaux granivores morts (15 000-40 000 ng/g), et leurs plumes pr4sentaient des concentrations analogues, (9000-52 000 ng/g). Ces concentrations extr8mement 4lev4es n'ont 6t6 observ6es qu'a proximit4 d'entrepots de semences trait4es. On n'a pu ni capturer ni examiner d'oiseaux de proie.