Document 6M133qrQZedQ8rMoRKjrjyQR

Focus MOST UNWANTED Aldrin Chlordane V, - 3*'r*' ~ K DDT Dieldrin Dioxins and Furans. Endrin Heptachlor HCB Mi rex PCBs Toxaphene hile many chemicals can known as persistent organic pollutants Wenhance and even save lives (POPS) -- compounds that travel thou by ensuring food security and sands of miles, accumulate in the food protecting health, others aren't socbheanine, and persist in the environment, Although the effects of POPs on human health are unclear, the weight of the evidence indicates that high levels of exposure over the long term may con ficial. More specifically, a dozen chemi taking up to centuries to fully degrade. tribute to increasing rates of birth defects, cal compounds have been identified by It has been well documented that expo fertility problems, greater susceptibility to the United Nations Environment sure to POPs can cause birth defects, disease, diminished intelligence, and some Programme (UNEP) as powerful threats various cancers, immune system dys types of cancers in certain regions of the 1 to human and wildlife health on a global basis. These chemicals belong to a class function, and reproductive problems in wildlife. world. Of major concern for human health is the effect of exposure to POPs on the i A 18 Volume 107, Number 1, January 1999 Environmental Health Perspectives Focus Most Unwanted developing fetus. POPs can accumulate in human tissues and pass through the pla centa to the fetus. Furthermore, POPs have been detected in the breast milk of women throughout the world. Little is known about the effect of long-term, low levels of exposure to POPs, but emerging evidence indicates that many POPs may act as endocriie disruptors. In response to national and Interna tional concerns, UNEP assumed the lead in mounting the first international effort to control POPs on a global level. Initially, 12 POPs have been identiied as requiring urgent attention. These chemicals, which have been dubbed "the dirty dozen," include aldrin. chlordane. DDT, dieldrin, dioxins, endrin, furans, heptachlor, hexachlorobenzene (HCB), mirex, polychlori nated biphenyls (PCBs), and toxaphene. In February 1997, UNEP issued a for mal decision calling for international action to reduce or eliminate the release of POPs into the environment. The decision includes the requirement of an internation al, legally binding instrument, which the organization plans to have in place by the year 2000. According to UNEP, global cooperation is necessary due to the longrange transport of POPs; no government acting alone can protea its citizens or envi ronment from the threat of POPs. The chemicals are ubiquitous throughout the global environment-residues have been detested in Arctic human populations and wildlife, in regions far from where POPs are produced and released. Properties of POPS POPs are organic compounds that resist photolytic, biological, and chemical degra dation. Most aresemivolatiJe, which allows them to move long distances in the atmos phere before deposition occurs. POPs are transported across the globe by a process called the "grasshopper effect." This process, which is often seasonal, involves a repeated pattern of release of a chemical into the atmosphere, such as through evap oration, and its subsequent deposit else where, such as trough rainfall. Due to the persistent nature of POPs, the chemicals are spread widely throughout the world through numerous iterations of this cycle. Many POPs are halogenated (that is, they contain one or more elements of the halogen family, which indudes fluorine, chlorine, bromine, and iodine) and are characterized by low solubility in water and high solubility in lipids. These proper ties, combined with the chemicals' persis tence, allows them to bioconcencrate and bioaccumulate in the fatty tissues of organ ists. Bioconcentratiofl to the uptake of a chemical dirccdf from water into an aquatic organism, while bioaccumulation refers to the process of uptake from both water and dietary sources. These processes lead to biomagnification, in which tissue concentrations of a contaminant increase as it passes through two or more trophic levels in the food chain. Bioconcentration is measured as a ratio of the amount of a chemical concentrated in an organism compared to the amount of the chemical in the surrounding environment. For example, if the bioconcentration factor of a chemical in a fish is 5,000, then there is 5,000 times the amount of chemical in the ftsh as in the water. Nine of the 12 POPs are pesticides used on agricultural crops and for public health vector control. PCBs are used for industrial purposes, while dioxins and furans are unintentional industrial by products that have no known use. In the 1970s, many countries banned or severely restriaed the use of all nine pesticides and PCBs, and implemented pollution controls to prevent the release of dioxins and furans. However, it is thought that all nine pesticides and PCBs are still used in many countries today. 'While there is some infor mation available about the volume of worldwide POPs production, little is known about the specific uses for POPs in different countries and the actual quanti ties being used. Efforts to address these questions are currently underway by sever al organizations, including the Food and Agriculture Organization (FAO) of the United Nations, the United Nations Economic Commission for Europe, the World Bank, and UNEP. At UNEP's request, the World Health Organization's (WHO) International Programme on Chemical Safety prepared a report that was published in December 1995 entitled A Review of the Persistent Organic Pollutants: DDT, Aldrin, Dieldrin, Endrin, Chlordane, Heptachlor, Hexachlorobenzene, Mirex, Toxaphene, Polychlorinated Biphenyls, Dioxins, and Furans. The report provides an extensive review of the literature, profiling each of the 12 POPs targeted for elimination. The following summaries provide an overview of the report's data on each chemical. Aldrin. Aldrin is a pesticide usd to con trol sail insects such as termites, grasshop pers, corn rootworm, wireworms, and rice water weevils. It has been widely used to protect crops such as corn and pota toes, and to protect wooden structures from termites. In plants and animals, aldrin Is readily metabolized to dieldrin, another of the 12 POPs targeted by UNEP. Because it is per sistent and hydrophobic, aldrin has been found to bioconcentrate in animal tissues, mainlyas dieldrin and its other conversion products. Aldrin is toxic to humans and is lethal to an adult male at a dose of about 5 g, equivalent to 83 mg/kg body weight (bw). Symptoms of aldrin intoxication include headache, dizziness, nausea, general malaise, and vomiting, followed by muscle twitching, myoclonic jerks, and convul sions. Research has suggested that occupa tional exposure to aldrin, in conjunction with dieldrin and endrin, may be associat ed with an increase in liver and biliary can cer. Aldrin may also affect the immune response. The International Agency for Research on Cancer (1ARC) concluded that aldrin is not classifiable in terms of its carcinogenic ity in humans, as there is inadequate evi dence of carcinogenicity in humans and limited evidence in animals. Research has shown that reproductive effects occur in the offspring of pregnant rats dosed with 1.0 mg aidrin/kg bw sub cutaneously. Offspring experienced a decrease in the median effective time for incisor teeth eruption and an increase in median effective time for testes descent, which indicates possible endocrine disrup tion. Residues of aldrin have been detected in birds, eggs, scavengers, predators, fish, frogs, invertebrates, and soil. It is thought that ingestion of rice treated with aldrin as well as me consumption of organisms con taminated with aldrin caused the deaths of waterfowl, shorebirds, and passerines along the T&ss Gulf coast from 1967 to 1971. Aldrin residues have also been detected in fish in Egypt. For humans, dairy products and mats are the primary sources of exposure to aldrii. In studies in Vi^tran and India in 1992 on residue of persistent organochlorine compounds and their implications for human dietary exposure, researchers calcu lated that the average daily intake of both aldrin and dieldrin was 19 )ig/person in India, which exceeds the provisional tolera ble daily intake of 0.1 flg/kg bw recom mended by the Joint FA0T5CT10 Meeting on Pesticide Residues (JMPR) in 1977. Aldrin has been banned in several coun tries, and is severely restricted in many oth ers, such as Canada and the United States, as well as in the European Union. Chlordane. Chlordane is a broad-spec trum contact insecticide used on agricul tural crops including vegetables, small grains, maize, other oilseeds, potatoes, sug arcane, sugar beets, fruits, nuts, cotton. 1 ,and jute. It has also been extensively used trol, particularly against mosquitoes that tions on Its use in many developed coun to control termites. CMordane binds spread malaria. DDT and related compounds are very tries. The use of D DT has been banned in at least 34 countries and severely restricted ceaditf to aquatic sed persistent in the environment; up to 50% in 34 others. Iments and biocon ofaa application can remain In the soil for DieIdrin. centrates In the fit of 10-15 years. Bioconcentration factors of Dieldrin was tradi organisms. Data sug 154.100 for Fathead minnows and 51,335 tionally used In api gest that chlordane is for rainbow trout have been reported. culture In the con bioconcentrated as opposed to being C h jo rda n e DDT has been detected in virtually all organochlorine monitoring programs and trol of soil insects, as well as In public bioaccumulated. _________________ is believed to be ubiquitous throughout the health protection to Bioconcentration fac glob?! environment. control several insect tors of 37,800 for fathead minnows and Some evidence suggests that DDT may vectors. Primary uses 16,000 for sheepshead minnows have been suppress the immune system, and research today include con reported. The half-life of chlordane in soil shows that perinatal administration of trolling termites, wood borers, and textile has been estimated to be approximately 1 weakly estrogenic pesticides such as DDT pests. year. produces estrogen-like alterations of repro Its persistence, along with Its high lipid Significant changes have been reported in the immune systems of people who ductive development. Limited data suggest a link between DDT and a risk of breast solubility, allows dieldrin to bioconcentrate and biomagniiy In organisms. In fish, bio- complained of health effects that they asso ciated with chlordane exposure. While cancer. LARC has classified DDT as a pos sible human carcinogen, based on inade concentrationfactors of 12,500 for guppies and 13,300 for sculpins have been report there is inadequate evidence of the carcino quate evidence of the carcinogenicity in ed. Dieldrin residues have been detected In genicity of chlordane In humans, there is humans, but sufficient evidence in experi air, water, soil, and the tissue of fish, birds, sufficient evidence in experimental ani mals, and IARC has therefore classified mental animals. DDT Is highly toxic to fish and can and mammals, including humans and human breast milk. Because aldrin is con chlordane as a possible human carcinogen. affect fish behavior. In one study, Atlantic verted to dieldrin in many organisms, the In a 1968 study in which mice were fed salmon hatched from eggs exposed to levels of dieldrin reflect the total concen diets containing 25-100 mg chlordane for DDT experienced impaired balance and trations of both compounds. Dieldrin six generations, researchers found that delayed appearance of normal behavior binds strongly to sail particles and is there doses of 100 mg/kg bw caused decreases In patterns. DDT is also acutely toxic to fore resistant to leaching Into groundwater. viability In the first and second genera birds, and received extensive publicity in The half-life of dieldrin in temperate soils tions. The third generation produced no the 1970s for its adverse effects on bird is approximately 5 years. offspring. At doses of 50 mg/kg bw, viabil reproduction, causing eggshell thinning In a study published in the 5 ity was decreased In the third and fourth and adversely impacting reproductive suc December 1998 Issue of The Lancet, genemaons. At doses of 25 mg/kg bw, no cess. DDT has also been linked with femi researchers at the Copenhagen Center for statistically significant effects were nization and altered sex ratios of western Prospective Population Studies in Observed. Actions to ban the use of chlordane have been taken in many countries, and its gull populations off the coast of southern California and herring gull populations in the Great lakes. Denmark assessed the risk of breast cancer In women who had serum samples taken In 1976. They found that the risk of breast use is severely restricted or limited to nonagricultural uses in several others. Because of these agricultural restrictions, food does not now appear to be a major pathway of DDT and its metabolites have been detected in foods around the world, which is thought to be the primary route of human exposure. Residues in domesticated cancer was twice as high in women with the highest serum concentrations of dieldrin as that in women with the lowest con centrations, and a significant human exposure. However, due to its con tinued use in termite control, exposure to chlordane in the air may be an important source of exposure for the U.S. population. Chlordane has been detected in the indoor air of residences in the United States and in Japan. animals have declined steadily over the past dose-response relation was apparent. 20 years, but in a 1989-1991 survey of Dieldrin is toxic to humans, and the Spanish meat and meat products, 83% of symptoms of Intoxication are essentially lamb samples contained at least one of the the same as those for aldrin. There is limit- DDT metabolites being Inveshgated. in a - --ed-evidence that cyclodienes--a class of 1992 study in Vietnam, DDT was the organic Insecticides that Includes dield- most common organochlorine detected in rin-may affect immune responses. DDT. During foodstuffs, and the estimated daily intake of Because there is inadequate evidence that World War II, DDT and its metabolites was 19jig/per- dieldrin is a carcinogen in humans and DDT was used son/day. In India, the estimated dally limited evidence in experimental animals, extensively to pro Intake has been found to be 48 gg/per- IARC concluded that dieldrin is not classi tect soldiers and son/day for DDT and Its metabolites. fiable as to its carcinogenicityin humans. civilians from DDT has also been detected in human In studies on rats, the liver has been the malaria, typhus, and breast milk In Egypt and New Guinea. In a major target organ of dieldrin, as is the other diseases 1993 survey of compounds In the milk of case with other organochlorine com spread by insects. After the war, DDT was commonly used lactating mothers in four remote villages in Papua New Guinea, DDT was detected in pounds. Effects include increased liver-bw ratio, hypertrophy, and histopathological as a pesticide on a variety of agricultural 100% of the samples. changes. crops, especially cotton. While much of Widespread concern about the adverse Dieldrin has been found to be highly 1 the agricultural use has ceased, DDT is still being produced and used for vector con- environmental effects of DDT contributed to the Implementation of severe restric toxic to fish and frcgs in laboratory studies. In embryo-larval tests on the Xenopus laevis i A 20 Volume 107, Number I, January 1999 EnvironmentalHealthPerspectives Focus Most Unwanted frog, exposure to low concentrations of dieldrin resulted in spinal deformities after a IO-day exposure. In another study, white tailed deer were fed a diet containing dield rin for up to 3 years. While adult survival was not affected, fawns of treated does were smaller at birth and experienced greater postpartum mortaliry and diminished weight gain. Food, especially dairy products and animal meats, is the primary source of human exposure to dieldrin. Dieldrin was the second most common pesticide detect ed in a survey of U.S. pasteurized milk published In 1993. Dieldrin has also been detected In Spanish meat, with residues found In the far of 8-15% of pork prod ucts and In 28% of poultry sausage. Action to ban dieldrin has been taken in many countries, and numerous others have restricted its use. Dioxins and furam. Dioxins and furans are two groups of planar tricyclic compounds rhat have similar chemical structures and prop erties. There are a total of 210 dioxins Dioxins and Furans and furans. Dioxins are released as an incineration by-product in the production of pesticides and other chlorinated substances, while furans are a major contaminant of PCBs. Both have been detected in emissions from the incin eration of hospital waste, municipal waste, hazardous waste, car emissions, and the burning of coal, peat, and wood. Dioxins and furans are lipophilic, insoluble in water, and highly persistent in the environ ment. Both have been detected in Arctic organisms. The only persistent human health effect clearly associated with exposure to dioxins is chloracne, a skin condition resembling acne caused by exposure to chlorinated hydrocarbons. Other reported health effects include peripheral neu ropathies, fatigue, depression, personality changes, hepatitis, enlarged liver, abnormal enzyme levels, and porphyria cutanea tarda, a disorder characterized by liver dys function and photosensitive cutaneous lesions. However, no causal relationships for dioxins have been established for these effects, In a 1991 study of 1,520 workers known to have been exposed to 2,3,7,8tetrachlorodibenzo-p-dioxin (TCDD) for at least 1 year and with a latency of at least 20 years between exposure and diagnosis of disease, a slight but significantly elevated mortality from soft tissue sarcoma and can cers of the respiratory system was identi fied. IARC has classified 2,3,7,8-TCDD as a possible human carcinogen. Other dloxins are currently deemed not classifiable by IARC as to their carcinogenicity in humans. Common effects of dioxin exposure on animals include wasting, hepatotoxicity, chloracne, epidermal changes, and gastric lesions. In both male and female rats, diox ins are associated with adverse effects on the reproductive systems. Effects in males include altered regulation of luteinizing hormone secretion, reduced testicular steroidogenesis, reduced plasma androgen concentrations, reduced testis and accesso_ry sex organ weights, abnormal testis mor phology, decreased spermatogenesis, and reduced fertility. Effects in females include hormonal irregularities in the estrous cycle, reduced litter size, and reduced fertility. In a 1988 study on fish, exposure to dioxins and furans caused delayed mortality and behavioral changes such as lethargic swim ming, feeding inhibition, and lack of response to external stimuli. Fish In early life stages are extremely sensitive to dioxins and furans. Food of animal origin is the primary source of human exposure to dioxins and furans. The release of dioxins and furans into the environment can be eliminated through the establishment of pollution con trols. Such controls have been implemented in many developed countries, which has resulted in a significant reduction in the production of dioxins and furans. Endrin. Endrin is a foliar insecticide used mainly on field crops such as cotton and grains. It is also used as a rodenticide to control mice and voles. Endrin is rapidly metabolized by ani mals and does not accumulate in fat to the same extent as other compounds with sim ilar structures. It enters the atmosphere by volatilization, and can contaminate surface water from soil runoff. The half-life of endrin In soil may be up to 12 years, depending on local conditions. Endrin is toxic to humans. Symptoms of mild intoxication include dizziness, weakness of the legs, abdominal discom fort, and nausea, while more severe polsoning results in repeated, violent, epilepti form convulsions lasting several minutes, followed by setniconsciousness or coma. Limited evidence suggests that endrin may depress the Immune response, IARC deter mined that endrin Is not classifiable In terms of its carcinogenicity in humans. Endrin is highly toxic to fish, with most IC50 values --indicating the concen tration required to kill 50% of the test organisms--below 1.0 Jig/L. One study exposed two groups of sheepshead minnow embryos to 0.31 and 0.72 gg/L for 23 weeks. All hatched early. Those exposed at 0.31 pg/L experienced stunted growth, and some died, while all those exposed to 0.72 pg/L died by the ninth day. The main source of human exposure to endrin is fcod, but it is thought that the current intake is usually below the accept able daily intake recommended by the JMPR. Recent monitoring data are not available, because most recent food surveys have not included endrin. The use of endrin has been banned in several countries and severely restricted in many others. Heptachlor. Heptachlor is a non- systemic stomach and contact Insecticide, used primarily against soil insects and ter mites, as well as against cotton insects, grasshoppers, some crop pests, and malarial mosquitoes. Heptachlor is metabolized In animals to heptachlor epoxide, the toxicity of which is similar to that of heptachlor. Heptachlor is insoluble in water, soluble in organic solvents, and highly volatile. It binds readily to aquatic sediments and bio concentrates In the-fat of organisms. Bioconcentrarion factors of 9,500 and 14,400have been detected In fathead mlnnows for heptachlor and heptachlor epox Ide, respectively. The half-life of hep tachlor in soil is up to 2 years. A 1992 study of workers from a plant that produced heptachlor and endrin found a significant increase In bladder can cer, but the small number of deaths makes interpretation of the findings difficult. IARC has classified heptachlor as a possible human carcinogen. Symptoms of heptachlor poisoning In animals Include tremors and convulsions. Heptachlor has been strongly implicated in the population declines of several wild birds, Including Canadian geese and the American kestrel In the Columbia River Basin In the United States. Canadian geese at the Umatilla National Wildlife Refuge In Oregon experienced adult mortality and decreased reproductivesuccess as a result of exposure to heptachlor. American kestrels have also experienced reduced reproductive success. Researchers determined that heptachlor-treated seeds were the route of exposure for the geese. Residues of hep tachlor epoxide were detected in the brains 1 I of dead kestrels as well as In the eggs of' some nests, indicating that heptachlor is mealybugs in Hawaii. Mires has also been used industrially as a fire retardant in plas Symptoms of exposure include enlargement and hypersecretion of fhe transferred through the food chain, tics, rubber, paint, paper, and electrical Meibomian glands of the eyes, swelling of because kestrels are not seed-eaters. products. the eyelids, and pigmentation of the nails In a 1990 survey, heptachlor was detect Mirex is insoluble in water, causing it and mucous membranes, as well as occa ed in the blood of U,S. and Australian cat to bind strongly to aquatic sediments, and sional signs of fatigue, nausea, and vomit tle, and was the most frequently detected to bioconcentrate and biomagnify. ing. Subsequent symptoms include hyper organochlorine in both species. Heptachlor Bioconccntration factors of 2,600 in pink keratosis and darkening of the skin with has been banned in several countries and severely restricted in ochers. shrimp and 51,400 in fathead minnows have been reported. Mirex is one of the follicular enlargement and acneform erup tions, dong with secondary staphylococcal HCB. HCB is a most stable and persistent pesticides, with infection. IARC classifies PCBs as proba fungicide that was a half-life of up to 10 years. ble human carcinogens due to sufficient introduced in 1945 No injuries to humans resulting from evidence in experimental animals. for seed treatment, mirex exposure have been documented. The main source of human PCB expo particularly for the Mirex residues have been detected in sure is through food, especially fish. Many control of bunt, a fun human adipose tissue. IARC classifies people were exposed to PCBs through gal disease of cereal mirex as a possible human carcinogen due contaminated rice oil in Japan in 1968 grasses such as wheat to sufficient evidence of carcinogenicity in and Taiwan in 1979. Children born with and iye. HCB is also a experimental animals. in seven years to mothers exposed in by-product of the manufacture of industrid In studies on rats, short-term effects of Taiwan experienced hyperpigmentation, chemicals including carbon tetrachloride, mirex administered orally include deformed nails and natal teeth, intrauter perchloroethylene, trichloroethylene, and pentachlorobenzene. It is also a known impurity in several pesticide formulations. decreased body weight, hepatomegaly, induction of mixed-function oxidases, and morphological changes in liver cells. ine growth delay, poorer cognitive devel opment up to age seven, and behavioral problems. These children appeared to The best documented episode of Feeding rats 5 ppm mirex for 30 days catch up developmentally to control chil human exposure to HCB was the inges prior to mating and for 90 days after dren by age 12. Researchers believe these tion of HCB-treated seed grain in Turkey resulted in reduced litter size and effects were a result of the persistence of from 1954 to 1959. People who ingested increased parental mortality. Aquatic PCBs in the human body, which allowed the grain experienced photosensitive skin organisms, particularly crustaceans, are for prenatal exposure long after initial lesions, hyperpigmentation, hirsutism, sensitive to mirex. Mirex is also toxic to exposure occurred. This is consistent with colic, severe weakness, porphyrinuria, fish and can affect fish behavior. other reports of poor short-term memory and debilitation. An estimated In several plant species, a reduction in functioning in early childhood, such as 3,000-4,000 people developed porphyria germination and emergence has been asso that observed in 1990 in children exposed turcica, a disorder of heme biosynthesis, ciated with increases in concentrations of prenatally to PCBs through the mothers' and mortality reached 14%. Pregnant women who ingested the grain passed mirex. While the results are unclear, uptake, accumulation, and translocation of high consumption of Lake Michigan game fish containing PCBs and other POPs. HCB to their children via placental mirex by a variety of plant species has also Recent evidence suggests that persistent transfer and breast milk. These children been observed. halogenated aromatic hydrocarbons such developed "pembe yara" (or "pink sore," The primary source of exposure to as PCBs may also be linked to reproduc a disorder characterized by pink cuta neous lesions) and many had fevers, diar rhea, vomiting, weakness, convulsions, enlarged livers, and progressive wasting. At least 95% of these children died with in a year of birth. Twenty years after the exposure, a study of 32 people showed that porphyria persisted for years after ingestion of HCB. IARC has classified mirex in humans is food, especially meat, fish, and wild game, but intake is generally below established residue tolerances. Mirex has been banned in manv countries. PCBs. PCBs are mixtures of chlorinat ed hydrocarbons that have been used exten sively since 1930 for a tive and irnmunotoxic effects in wildlife. PCBs have been phased out in many countries. Toxaphene. Toxaphene is a nonsystemic contact insecticide that was introduced in 1949, n -and bccamcThe most HCB as a possible human carcinogen. HCB is banned in many countries, and variety of industrial uses, including as widely used insecti cide in the United Toxaphene its use has been severely restricted or vol dielectrics in trans States by 1975. It untarily withdrawn in several others. formers and large has been used primarily on cotton, cereal Miax. Mirex is a stomach insecticide capacitors, as heat exchange fluids, as paint grains, fruits, nuts, and vegetables, as well 1 with little contact activity that has been additives, in carbonless copy paper, and in plastics. There are 209 possible PCBs. as to control ticks and mites in livestock. Toxaphene is highly insoluble in water used primarily to PCBs in the environment may associ and its half-life in soil ranges up to 12 control fire ants in ate with organic components of soils, sedi years, depending on soil type and climate, the southeastern United States. It has ments, and biological tissues, or with dis solved organic carbon in aquatic systems. resulting in a tendency for it to biocon centrate. Bioconcentration factors of also been used to .control leaf cutters in The properties of PCBs--including low water solubility, high stability, and semi 4,247 in mosquito fish and 76,000 in brook trout have been detected. I South America, har volatility--favor long-range transport, and Toxaphene's properties favor long-range 1 vester termites in South Africa, western PCBs have been found in Arctic air, water, transport, and it has been detected in harvester ants in the United States, and and organisms. Arctic air. ( A 22 Volume 107, Number 1, January 1999 Environmental Health Perspectives Focus Most Unwanted In a 1974 study, eight women working in an area that had been sprayed with toxaphene at a rate of 2 kg/ha had a higher incidence of chromosome aberrations (acentric fragments and chromatid exchanges) than in control individuals. IARC classifies toxaphene as a possible human carcinogen. In a study using beagles, ingestion of 5.0 mg toxaphene/kg bw for 13 weeks resulted in increases in liver-bw ratio and serum alkaline phosphatase. Mild to mod erate dose-dependent histological changes were observed in the liver and thyroid. Toxaphene is highly toxic to some fish, causing effects such as reduction in weight__ and reduction in egg laying, hatching abil ity, and viability. The primary route of exposure is through food, but levels are generally below acceptable limits. Because it has been banned in at least 37 countries, recent food surveys have excluded toxaphene, and therefore, recent monitor ing data are unavailable. POPs Alternatives Alternatives are available for most of the 10 POPs that are used commercially. Most of these alternatives are other chemi cals to be used alone or in combination with biological controls. DDT is one of the most controversial POPs as far as being replaced goes because of its use in controlling the spread of malaria, of which there are approximately 300-500 clinical cases annually, according to the WHO. A 1998 report by the World Wildlife Fund entitled Resolving the DDT Dilemma outlines what it says are affordable alternatives to DDT that still address the urgent need to combat malar ia. These alternatives include pesticide- impregnated bed nets (reducing the need for interior spraying), odor-baited cloth targets to attract and destroy disease-carry ing insects, lower-risk pesticides used in rotation to avoid the development of resis tance, widespread elimination of mosquito breeding grounds, and introduction of natural predators and sterile insects. There are many challenges to sur mount in addressing the issue of alterna tives to POPs. One of the largest prob lems for developing countries is cost- many of the alternatives are more expen sive than the POPs they replace. In addi tion, the health effects of the alternative chemicals are still unclear; some are thought to be more acutely toxic and per haps more hazardous to the user than some of the POPs. Furthermore, educat ing and training individuals around the world on the hazards of POPs and the uses of alternatives will be a massive undertaking. In order to develop plans to imple ment the use of alternatives, officials first need to gain a better understanding of the current status of POPs, More information is needed about which countries are still using POPs, how they are using the chem icals, and in what quantities. uNEP is developing a comprehensive inventory of the global manufacture, use, and disposition of POPs that should be available early this year. The inventorywill be primarily based on country responses to a UNEP questionnaire and will also include data from other FAO, WHO, and UNEP projects, sucF as data on stockpiles of pesticides and other chemicals. The data will be used as a basis for a "clickable" world map on the POPs home page located at http://irptc.unep.ch/pops/default.html. Fatoumata Keita-Ouane, Scientific Affairs Officer for UNEP Chemicals in Geneva, Switzerland, explains: "The system enables the user to click on a country and view data relevant to that country. It also enables the user to select substances or data types to view, and to view a map that is color-coded or shaded by country to indicate the quantity for any parameter selected {e.g., DDT stocks, dioxin emis sions, chlordane imports, etc.)." Ouane says the report and the map should be finalized by February 1999. Brandy E. Fisher When it comes to the environment... S^Sw-cowsI The Myth Toxic Waste YOU CAN'T BELIEVE EVERYTHING YOU READ So you'd better know who you can trust. Environmental Health Perspectives draws on more than 25 years of scientific publishing, backed by the authority of the National Institutes of Health--National Institute of Environmental HealthSciences, to provide you with the most current and credible information available to help you make decisions about ycnut/health and tho environment. Each month we delve into the issues you care about such as: water, air, and soil pollution _ urban sprawl populationandworld health toxic pesticides t