Document B5R6oMGBXwBvbormgDEe0ZwMw

{ 1 i i while many chemicals can enhance and even save lives by ensuring food security and protecting health, others aren't so beneficial. More specifically, a dozen chemical compounds have been identified by the United Nations Environment Programme (UNEP) as powerful threats to human and wildlife health o n a global basis. These chemicals belong to a class known as persistent organic pollutants (POPS)- compounds that travel thousands of miles, accumulate in the food chain, and persist in the environment, taking up to centuries to fully degrade. I t has been well documented that exposure to POPs can cause birth defects, various cancers, immune system dysfunction, and reproductive problems in wildlife. 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 contribute to increasing rates of birth defects, fertility problems, greater susceptibility to disease, diminished intelligence, and some types of cancers in certain regions of the world. Of major concern for human health is the effect of exposure to POPs on the A 18 Volume 107, Number 1, January 1999 Environmental Health Perspectrves - Focus Most Unwanted developing fetus. POPs can accumulate in human tissues and pass through the placenta 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 international concerns, UNEP assumed the lead in mounting the first international effort to control POPs on a global level. Initially, 12 POPShave 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, polychlorinated biphenyls (PCBs), and toxaphene. In February 1997, UNEP issued a formal decision calling for international action to reduce or eliminate the release of POPSinto the environment. The decision includes the requirement of an international, legally binding instrument, which the organization plans to have in place by the year 2000. According to UNEP, global cooperation is necessvy due to the longrange transport of POPs; no government acting alone can protea its citizens or environment from the threat of POPS. The chemicals are ubiquitous throughout the global environment-residueshave been detested in Arctic human populations and wildlife, in regions far from where POPs are produced and released. Properdes ofPOPS POPs are organic compounds that resist photolytic, biological, and chemical degradation. Most are semivolatile, which allows them to move long distances in the atmosphere 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 evaporation, and its subsequent deposit else- where, such as through rainfall. Due to the persistent nature of POPS, the chemicals are spread widely throughout the world through numerous itcntions ofthis cyde. 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 solubiliry in lipids. These proper- ties, combined with the chemicals' penis- tence, alloars them m bioconcenaav and bioacaunuhtc in &e hQy tissuesof organ- isms.Bioconccnwioa &to the uptake o f a chemical d.iradyfnnn 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 fish 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 byproducts that have no known use. In the 1970s, many countries banned or severely restricted the use of all nine pesticides and PCBs, and implemented pollution ccintrols 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. W i l e there is some information available about the volume of worldwide POPs production, little is known about the specific uses for POPSin different countries and the actual quantities being used. Efforts to address these questions are currently underway by several 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, Akfrin, DuUrin, Endrin, Chlordane, Heptachlor, Hexachlorobenzene, Mirex, Toxaphene, Po!ychlorinated Biphenyls, Dioxins, and Furam. The report provides an extensive review of the literature, profiling each of the 12 POPs t a r p a i fbr elimination. The following summaries provide an overview of the report's data on each chemical. AIdriR Aldrin is a pesticide used to control soil insects sucb a5 termim, fpshap- pers, corn rootworm, wireworms, and r i a water weevils. It has been widely used to protect crops such as corn a n d potatoes, and to protcct 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 persistent and hydrophobic, aldrin has been found to bioconcentrate in animal tissues, mainly as 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 mglkg body weight (bw). Symptoms of aldrin intoxication include headache, dizziness, nausea, general malaise, and vomiting, followed by muscle twitching, myoclonic jerks, and convulsions. Research has suggested that occupational exposure to aldrin, in conjunction with dieldrin and endrin, may be associated with an increase in liver and b d i q cancer. Aldrin may also affect the immune response. The International Agency for Research on Cancer (LARC) 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 aldriikg bw subcutaneously. 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 disruption. Residues of aldrin have been detected in birds, eggs, scavengers, predators, fish, hogs, invertebrates, and soil. It is thought thzt ingestion of rice treated with aldrin as well as me consumption of organisms contaminated with aldrin caused the deaths of waterfowl, shorebirds, and passerines along rhe Texas Gulf coast from 1967 to 1971. Aldrin residues have also been detected in fish in Egypt. For humans, dairy products and meats are the primary sources of exposure to aldrii. In studies in Vietnam and India in 1992 on residua of persistent organode rine compounds and their implications for human dietary expure, resear&ers calmlated that the average daily intake of both aldrin and dieldrin was 19 pglperson in India, which ex& the provisional tolera- ble daily in& of 0.1 pglkg bw recom- mended by the Joint FAO/WHO Meeting on Pesticide Residues (JMPR) in 1977. Aldrin has been banned in several wunma,and is scvcrdy restricted in many others, such as Canada and the United States, as well as in the European Union. Gblonianc. Chbrdane i s a broad-spes- trum contact insaaicide used on agricultural crops including vegetables. small grains, rmiu, orbaoiiseads, potatoa, qarcane, sugar haw. fruits, nuts, cotton. 1 I 1 i .andjute It has a h been cxt& to COlKlol termites. Chlordane binds uscd mol, particulvly against mosquitoes that daa on its use in many dcvdopad corn- spndd aia The useof DDT has bcen banned in DDT and &cd compounds arc my a k 3 4 QHuluics uldscverelyrauictcd rcadiiy to aquatic sed- pasatutt in the environment; up to 5096 in34othels. iments and biocon- of am application can remain in the soil for Dieldrin. cenuprs in the fit of l&t5 years. Bioconcentration factors of Dieldrin was tradi- organisms. Data sug- 154.00for Fathead minnows and 51,335 tionally used in agri- gest that chlordane is for rainbow trout have been reported. culture in the con- bioconcentrated as D D T has been detected in virtually all ad of soil insccn,as opposed to being organochlorine monitoring programs and well as in public bioaccurnulated. is bdieved to be ubiquitous throughout the health protection to Bioconcenuation fic- gtoM 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- yeu. produces estrogen-like alterations of repro- Its persistence, along with its high lipid Si%nificant changes have been reported ductive development. Limited data suggest solubility, allom dieldrin to bioconcentrate in the immune systems of people who a link between DDT and a risk of breast and b i o e in organisms. In fish, bio- complained of health effects that they asso- cancer. LARC has classified DDT as a pos- concentration fictors of 12,500 for guppies ciated with chlordane exposure. While sible human carcinogen, based on inade- 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 geniaty 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- mental animals. and mammals, including humans and mals, and IARC has therefore classified D D T is highly toxic to fish and can 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 25100 mg chlordane for D D T experienced impaired balance and trations of both compounds. Dieldrin six generations, researchers found that delayed appearance of normal behavior binds strongly to soil particles and is there- doses of 100 mg/kg bw caused decreases in patterns. D D T 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. ~ G p r i n gA. t 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. gull populations off the coast of southern Denmark assessed the risk of breast cancer Actions to ban the use of chlordane California and herring gull populations in in women who had serum samples taken in have been taken in many countries, and its the Great Lakes. 1976. They found that the risk of breast use is severely restricted or limited to nona- D D T and its metabolites have been cancer was twice as high in women with gricultural uses in several others. Because detected in foods around the world, which the highest serum concentrations of dield- of these agricultural restrictions, food does is thought to be the primary route of rin as that in women with the lowest con- not now appear to be a major pathway of human exposure. Residues in domesticated centrations, and a significant human exposure. However, due to its con- animals have declined steadily over the past dose-response relation was apparent. tinued use in termite control, exposure to 20 years, but in a 1989-1991 survey of Dieldrin is toxic to humans, and the chlordane in the air may be an important Spanish meat and meat products, 83% of symptoms of intoxication are essentially i source of exposure for the U.S. population. Chlordane has been detected in the indoor air of residences in the United States and lamb samples contained at least one of the the same as thase for aldrin. There is limit- D D T metabolites being investigated. In a - - -edaridenttthat+&r-a class of 1992 study in Vietnam, D D T was the organic insecticides that includes dield- in Japan. most common organochlorine detected in rin-may affect immune responses. foodstuffs, and the estimated daily intake of Because there is inadequate evidence that D D T and its metabolites was 19 pglper- dieldrin is a carcinogen in humans and sodday. In India, the estimated daily limited evidence in experimental animals, 4 intake has been found to be 48 pg/persodday for D D T and its metabolites. D D T has also been detected in human IARC concluded that dieldrin is not classifiable as to its carcinogenicityin humans. In studies on rats, the liver has been the breast milk in Esrpt and New Guinea. In a major target organ of dieldrin, as is the 1993 survey of compounds in the milk of case with other organochlorine com- lactating mothers in four remote villages in pounds. Effects include increased liver-bw I After the war, DDT w& commonly used Papua New Guinea, DDT was detected in ratio, hypertrophy, and histopathological as a pesticide on a variety of agriculturd 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 environmental effects of DDT contributed toxic to fish and frogs in laboratory studies. being produced and used for vector con- to the implementation of severe restric- In embryo-Id tests on the Xmpopw hvis A 20 Volume 107. Number I , Jainuary 1999 EnvironmentalHealthPerspemes .Focus Most Unwanted frog, exposure to low concentrations of fied. IARC has classified 2,3,7,8-TCDD as Endrin is highly toxic to fish, with dieldrin resulted in spinal deformities after a a possible human carcinogen. Other diox- most LC50 values-indicating the concen- IO-day exposure. In another study, white- ins are currently deemed not classifiable by tration required to kill 50% of the test tailed deer were fed a diet containing dield- IARC as to their carcinogenicity in organisms-below 1.O pg/L. O n e study rin for up to 3 years. While adult survival humans. exposed two groups of sheepshead minnow was not affected, fawns of treated does were Common ef)kcts of dioxin exposure on embryos to 0.31 and 0.72 pglL for 23 smaller at birth and experienced greater animals include wasting, hepatotoxicity, weeks. All hatched early. Those exposed at postpartum mortaliry and diminished chloracne, epidermal changes, and gastric 0.3 1 pg/L experienced stunted growth, weight gain. lesions. In both male and female rats, diox- and some died, while all those exposed to Food, especially dairy products and ins are associated with adverse effects on 0.72 pg/L died by the ninth day. animal meats, is the primary source of the reproductive systems. Effects in males The main source of human exposure to human exposure to dieldrin. Dieldrin was include altered regulation of luteinizing endrin is fcod, but it is thought that the the second most common pesticide detect- hormone secretion, reduced testicular current intake is usually below the accept- ed in a survey of U.S. pasteurized milk steroidogenesis, reduced plasma androgen able daily intake recommended by the published in 1993. Dieldrin has also been concentrations, reduced testis and accesso- JMPR. Recent monitoring data are not detected in Spanish meat, with residues J-I segrg-weights, abnormal testis mor- available, because most recent food surveys found in the far of 8-15% of pork prod- phology, decreased spermatogenesis, and have not included endrin. The use of endrin ucts and in 28% of poultry sausage. Action reduced fertility. Effects in females include has been banned in several countries and to ban dieldrin has been taken in many countries, and numerous others have restricted its use. Dioxins and firans. Dioxins and furans are two groups of planar tricyclic compounds rhat have similar chemical structures and prop- rerties. There are a hormonal irregularitiesin 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 swimming, 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 severely restricted in many others. H e p t a c h l o r-. I Heptachlor is a nonsystemic stomach and con:act insecticide, used primarily against soil insects and termites, as well as against cotton insects, grasshoppers, some crop pests, and maaria mosquitoes. total of 210 dioxins furans. The release of dioxins and furans Heptachlor is metabolized in animals and furans. Dioxins into the environment can be eliminated to heptachlor epoxide, the toxicity of are released as an incineration by-product through the establishmentof pollution con- which is similar to that of heptachlor. in the production of pesticides and other trols. Such controls have been implemented Heptachlor is insoluble in water, soluble in chlorinated substances, while furans are a in many developed countries, which has organic solvents, and highly volatile. It major contaminant of PCBs. Both have resulted in a significant reduction in the binds readily to aquatic sediments and bio- been detected in emissions from the incin- production of dioxins and furans. concentrates in t h e fat of organisms. eration of hospital waste, municipal waste, Endrin. Endrin is Bioconcentrarion factors of 9,500 and hazardous waste, car emissions, and the a foliar insecticide 14,400have been detected in hthead min- burning of coal, peat, and wood. Dioxins used mainly on field nows for heptachlor and heptachlor epox- and furans are lipophilic, insoluble in crops such as cotton ide, respectively. The half-life of hep- water, and highly persistent in the environ- and grains. It is also tachlor kmil is up to 2 years. ment. Both have been detected in Arctic used as a rodenticide A 1992 study of workers from a plant organisms. to control mice and that produced heptachlor and endrin The only persistent human health voles. found a significant increase in bladder can- effect clearly associated with exposure to Endrin is rapidly cer, but the small number of deaths makes dioxins is chloracne, a skin condition metabolized by ani- interpretation of the findings difficult. resembling acne caused by exposure to mals and does not accumulate in fat to the IARChas classified heptachlor as a possible chlorinated hydrocarbons. Other reported same extent as other compounds with sim- human carcinogen. - health effects include peripheral neuropathies, fatigue, depression, personality ilar structures. It enters &e atmosphere by volatilization, and can contaminate surface Symptoms of heptachlor poisoning in animals include tremors and convulsions. changes, hepatitis, enlarged liver, abnormal water from soil runoff. The half-life of Heptachlor has been strongly implicated in enzyme levels, and porphyria cutanea endrin in soil may be up to 12 years, the population declines of several wild tarda, a disorder characterized by liver dys- dependmg on I d conditions. birds, including Canadian geese and the function and photosensitive cutaneous Endnn i s toxic to humans. Symptoms American kestrel in the Columbia River lesions. However, no c a d relationships of mild intoxication include dizziness, Basin in the United Stam. Canadian geese for dioxins have been established for these weakness of the legs, abdominal discom- at the Umatilla National Wildlife Rduge &ern. In a 1991 study of 1,520 workers fort, and while more severe poison- in Or-n experienced adult mortality and known to have been exposcd to 2,3,7,8- ing results in repeated, violent, epilepti- decreased reproductive SUC~CSSas a result of tetrachlorodibenm-pdiorin (TCDD) for form convulsions lasting several minutes, exposure to heptachlor. American kestrels at least 1 year and with a hamyof at least followed by scrniconsciousness or coma. have also a p e r i e n d raduced reproductive 20 yars between exposure?addiagnosisof Limited midemx suggats that endrin may sucws. Rcscuchers daaminad that hep- disease, a slight but signif%.nntly elevated depress the immune rapoarsc. LhRC deter- tachlor-treated seeds were the route of mortality from safi tissue ssmoma and can- mined that endrin is not classifiable in aposure for the gecse. Rcsiducs of hep- cers of the respiratory system was identi- tams of its c a n i q p i c i t y in humans. tachlor epoxidewere dcorxttd in the brains I b I i d of dead kestrels as well as in the eggs of mealybugs in Hawaii. Mirex has dso k Symptoms of exposure include some nests, indicating that heptachlor is used i d u s t d y as a fire reurdant in pbs- enlargement and hypersecretion of the transferred through the food chain, tics, rubber, paint, paper, and electrid Meibomian glands of the eya, sw&ng of becausekestrels are not seed-caters. 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 o w - ed in the blood of US.and AUS& at- 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 shrimp and 51,400 in fathead minnows follicular enlargement and acneform e r u p scverely restricted in ochers. have been reported. Mirex is one of the 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 inrroduced 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 rye. HCB is also a experimental animals. in seven years to mothers exposed in by-prbduct 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 decreased body weight, hepatomegaly, ine growth delay, poorer cognitive devel- pentachlorobenzene. I t is also a known induction of mixed-function oxidases, opment up to age seven, and behavioral impurity in several pesticide formulations. and morphological changes in liver cells. problems. These children appeared to T h e best documented episode of Feeding rats 5 pprn 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,OOO 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 mirex. While the results are unclear, high consumption of Lake Michigan game women who ingested the grain passed uptake, accumulation, and translocation of fish containing PCBs and other POPS. H C B t o 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- mirex in humans is food, especially meat, tive and irnmunotoxic effects in wildlife. neous lesions) and many had fevers, diar- fish, and wild game, but intake is generally PCBs have been phased out in many rhea, vomiting, weakness, convulsions, below established residue tolerances. Mirex countries. enlarged livers, and progressive wasting. has been banned in manv countries. Toxaphene. I At least 95% of these children died within 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 HCB as a possible human carcinogen. PCBs. PCBs are mixtures of chlorinated hydrocarbons that have been used extensively since 1930 for a variety of industrial Toxaphene is a nonsystemic contact insecticide that was introduced in 1949, rnd-4-ecmdte-most widely used insecti- HCB is banned in many countries, and uses, including as cide in the United 1 its use has been severely restricted or vol- dielectrics in trans- untarily withdrawn in several others. formers and large States by 1975. I t has been used primarily on cotton, cereal Mirex.Mirex is a stomach insecticide capacitors, as heat exchange fluids, as paint grains, fruits, nuts, and vegetables, as well with little contact additives, in carbonless copy paper, and in as to control ticks and mites in livestock. activity that has been plastics. There are 209 possible PCBs. 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 ments, and biological tissues, or with dis- resulting in a tendency for it to biocon- United States. It has solved organic carbon in aquatic systems. centrate. Bioconcentration factors of also been used to The properties of PCBs-including low 4,247 in mosquito fish and 76,000 in .control leaf cutters in water solubility, high stability, and serni- brook trout have been detected. South America, har- volatiliry-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 moderate 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 monitoring data are unavailable. POPS Alternatives Alternatives are available for most of the 10 POPs that are used commercially. Most of these alternatives are other chemicals 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 W H O . 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 malaria. These alternatives include pesticideimpregnated bed nets (reducing the need for interior spraying), odor-baited cloth targets to attract and destroy diseax~arrying insects, lower-risk pesticides used in rotation to avoid the development of resistance, widespread elimination of mosquito breeding grounds, and introduction of natural predators and sterile insects. There are many challenges to surmount in addressing the issue of alternatives to POPS.One of the largest problems for developing countries is costmany of the alternatives are more a p e n sive than the POPs they replace. In addition, the health effects of the alternative chemicals are still unclear; some are thought to be more acutely toxic and pcrhaps more hazardous to the user than some of the POPs. Furrhermorr, d u c a t - ing and training individuals a r d the world on the hazards of POPS and the uses of alternatives will be a massive undertaking. In order to develop plans to implement 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 chemicals, 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 inclu_d_e_da_ta _from other FAO, WHO, and UNEP projects, s k k a d a t a on stockpiles of pesticides and other chemicals. The data will be used as a basis for a "clickable" world map on the POPShome page located at http://irptc.unep.ch/pops/default.html. Fatoumata Keita-Ouane, Scientific Affairs Oficer 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 emissions, chlordane imports, etc.)." Ouane says the report and the map should be finalized by February 1999. Brandy E.Fisher So you'd better know who you can hutt.Environmental Health Peprprccives draws on more than 25 years of scientific publishing, bacLeA by the authority of the National Institutesof Health-National lnstitute of Environmental Health SCkW?s, to provide you with the most cunwtand and tho environment. &I montk we deive into the ,air, ;ad Mil poilu urban sprawl populationand world h toxic pesticides environmental~roductsand xrvkes t t