20. Persistent Organic Pesticides in Costa Rica

by Ms. Luisa Eugenia Castillo

Pesticides were introduced in Central America before 1950 (Murray, 1994; Hilje et al., 1987). By 1970 pesticide imports amounted to 5.8 million kilograms. During this first decades organochlorines were widely in use.

Most organochlorines were restricted in the early 1970s in the developed world. The majority of them are currently banned in Central America (Wesseling & Castillo, 1992), but in general they were banned or restricted one decade later than in the developed countries.

Costa Rica first restricted the traditional organochlorines in 1980 and banned them between 1988 and 1990 (Table 1). No importation of DDT, aldrin, chlordane, dieldrin, endrin, or toxaphene for agricultural use took place after 1983. Organochlorine use diminished from approximately 815 tons during 1977 to 1979 to approximately 52 thousand kg in 1983 to 1985 (Castillo et al. 1997; De la Cruz, 1994; Hidalgo, 1986). However, the Ministry of Health reported the use of 21 thousand kg of DDT for malaria control purposes between 1983 and 1985 (Hidalgo, 1986). Table 2 shows the pattern of importation for major organochlorines during the period. 1977-1991.

Source: Ministry of Health, Costa Rica

Table 2: Major OCS imported to Costa Rica in metric tons, 1977-1991

Use of heptachlor and lindane increased after the importation of other organochlorines decreased. Imports of these two compounds amounted to 155 thousand kg in the period 1986 to 1991 (Table 2). Heptachlor was banned in 1990, lindane was restricted in 1988. The importation of mirex was also increased, especially after 1985, 111 tons were imported between 1985-1988, 164 in the period 1989-1991 and 122 during 1992-1993. No importation of this product has occurred after.

Currently the most imported organochlorine in use is endosulfan, with 45 tons imported in 1992-1993, 55 in 1994-1995 and 64 in only the year 1996 (Database of the Central American Institute for Studies on Toxic Substances, Universidad Nacional, Costa Rica). Endosulfan is used in ornamental plants and vegetables. It is also the pesticide recommended by the Ministry of Agriculture to control the insect pest of the Abroca del cafe whenever it occurs in Costa Rica. Coffee is one of the most important crops of Costa Rica, cultivated in approximately 100 000 ha of the highlands of the country.

Import and use of pesticides in Central America shifted during the 80's to other less persistent but more toxic pesticides. Currently the main group of pesticides used in Costa Rica are organophosphates, carbamates and pyrethroids among the insecticides; the dithiocarbamic fungicides; and phenoxyacids, dipyridyls and more recently triazines as herbicides (Chaverri & Blanco, 1995; Wesseling & Castillo, 1992)

High levels of DDT and metabolites have been demostrated in agricultural areas and malaria control areas. Table 4 show the residues found in human milk and adipose tissue. The values are among the highest found in different parts of the world (Umańa & Constenla, 1984; Barquero & Thiel, 1986 and Barquero & Constenla, 1986).

Table 4: Average concentration and ranges of s DDT (in mg/kg) in human milk and adipose tissue in Costa Rica.

Most studies of organochlorine residues in the environment have been conducted in aquatic ecosystems, they correspond to a period where organochlorine use had already decreased and thus are not representative of the previous decade. A summary of these studies is included in Table 5.

Table 5: Summary of pesticides studies in the aquatic environment in Central America

b OC = organochlorine pesticides; dw = dry weight; fw = fresh weight; cmax= highest concentration found; OC= organochlorine pesticides. xx-xx concentration range; 3X sum of all residues related with one active ingredient mentioned in the reference (i.e. 3DDT=pp=DDD+pp=DDE+pp=DDT+op=DDD+op=DDE+op=DDT).

The frequency of occurrence of organochlorines in fish collected in the banana production area and in Lake Arenal, Costa Rica in 1987 and 1988 (von Düszeln, 1988) was 49% for HCB, 46% for dieldrin, 43% for heptachlor, 38% for DDE and 30% for lindane.

De la Cruz (1994) found lindane, DDT's and chlordane accounting for most of the total organochlorine residues measured at different study sites in the mussel Anadara tuberculosa in the Nicoya Gulf (Pacific Coast) of Costa Rica during 1990 and 1991 (72%-91%). According to a survey conducted by the International Mussel Watch Project (Farrington & Tripp, 1994) Pacific and Caribbean coasts of Central America in 1991, DDT's are the most prevalent organochlorine compounds found in biota. For Costa Rica the highest value found in the Pacific Coast was of 38.8 mg/kg for 3DDTs and 5.9 for 3chlordanes mg/kg dry weight.

De la Cruz (1994) found a maximum concentration of 134 mg/kg dry weight of total DDT's from a total of 137 mussels collected on the Pacific Coast of Costa Rica between 1988 and 1991.

During 1993-1994 a study was conducted in the Basin of La Suerte River, in the Atlantic lowlands of Limon, Costa Rica, an important banana producing area (Castillo et al., 1995). Samples of water, sediments and occasionally aquatic organisms were collected in effluents, creeks and the main river. Samples were analyzed for organochlorine, organophosphates and other pesticides used in banana production. Organochlorines analyzed included HCHs, heptachlors, aldrin, endosulfans and DDTs. Detection limits for all organochlorines in the water samples were in the range of 0.01 to 0.02 ug/L except for p,p=-DDT= (0.04), o,p=-DDT= 0,08 and p,p=-DDT= 0.1. No organochlorine residues were detected in this samples.

To investigate atmospheric transport from nearby regions, Standley and Sweeney (1995) analyzed organochlorines in stream mayflies, sediments and terrestrial vegetation of river catchments of primary forest in Costa Rica. Several organochlorine pesticides were found in the mayflies; endosulfans were the dominant compounds. The authors attribute the origin to long- and short-range atmospheric transport. More research will be necessary to have a clearer picture of atmospheric transport and deposition of this compound.

Hidalgo (1986) found organochlorines in eggs of 8 different species of aquatic birds. Between 1983 and 1984 a total of 137 eggs were collected on Pajaros Island, a nesting site located near the Nicoya Gulf (Pacific Coast of Costa Rica). Residues of p,p'DDE were found in 100% of the eggs analyzed; the highest found in wood stork eggs (Mycteria americana) and lowest in white ibis, Eudocimus albus. Heptachlor epoxide, HCB, p,p'DDT and endrin were present in a high percentage of the samples. For all except two species, a strong correlation was found between shell thickness and p,p' DDE residues. The author observed cracks in some of the eggs of M. americana with the highest concentrations of DDE. (Table 6).

Table 6 :

n= number of samples

* = statistically significant p<0.05; ** = p<0.01

Although not many studies have been carried out in Costa Rica regarding non chemical control of mosquito vectors the preliminary results of an ongoing study by Stefan Schafer (IRET, personal communication) have had promising results (Table 7).

Although not many studies have been carried out in Costa Rica regarding non chemical control of mosquito vectors the preliminary results of an ongoing study by Stefan Schafer (IRET, personal communication) have had promising results (Table 7).

Source: Schaper, S. , personal communication

According to the limited number of studies carried out in Costa Rica it is obvious that organochlorine compounds have been widely distributed in the environment and human population. Effects such as the well known egg-shell thinning phenomenon has also been demostrated. A follow-up of these studies would be convenient.

Considering the increasing use of endosulfan, its use, residue levels in the environment, in the human population and its possible effects should be closely monitored.

Research in non-chemical alternatives for mosquito control should be promoted.

Barquero M. & M.A. Constenla. 1986. Residuos de plaguicidas organoclorados en tejido adiposo humano en Costa Rica. Rev. Biol. Trop. 34(1):7-12.

Barquero, M. & R. Thiel. 1986. Residuos de DDT y bifenilos policlorados en leche humana. Rev. Costarricense Cienc. Med. 7(2):133-136.

Castillo, L.E., C. Ruepert, E. Solís and E. Martínez. 1995. Ecological consequences from pesticide use. GTZ PN 90.2136.1-03.103 Final Report, Tropenökologisches Begleitprogramm, Deutsche Gessellschaft für Technische Zusammenarbeit (GTZ), Heredia, Costa Rica.

Chaverri, F. and J. Blanco. 1995. Importación, formulación y uso de plaguicidas en Costa Rica. Período 1992-1993. Final Report to Pan American Health Organization (PAHO), Pesticide Program: Development, Health and Environment, Universidad Nacional, Heredia, Costa Rica.

De la Cruz, E. 1994. Stable pollutants in the bivalve Anadara tuberculosa, from the Nicoya Gulf, Costa Rica. Ph.D. thesis. Vrije Universiteit Brussel, Brussels.

Düszeln von, J. 1988. Analysis of pesticides in Costa Rica with special emphasis on water and fish samples. GTZ PN 85.2039-7, Technical Report, Deutsche Gessellschaft für Technishe Zusammenarbeit (GTZ), Bremen.

Farrigton, J.W. and B.W. Tripp. 1994. International mussel watch project, initial implementation phase. Final Report. International Mussel Watch, Coastal Chemical Contaminant Monitoring Using Bivalves, Woods Hole, Massachusetts.

Hidalgo, C. 1986. Determinación de residuos de plaguicidas organoclorados en huevos de ocho especies de aves acuáticas, colectados durante 1983-1984 en la Isla Pájaros, Guanacaste, Costa Rica. M.Sc. thesis. Universidad de Costa Rica, San Pedro, Costa Rica. 89 p.

Hilje L., L.E. Castillo, L. Thrupp, and C. Wesseling. 1987. El Uso de los Plaguicidas en Costa Rica. Ed. Heliconia /UNED, San José, Costa Rica.

Matus, F.M. and I.Beck, eds. 1991. Uso, Manejo y Riesgos Asociados a Plaguicidas en Nicaragua. Programa Regional de Plaguicidas, CSUCA/UNI/UNA/UNAN, Nicaragua.

Murray, D. 1994. Cultivating Crisis, the human cost of pesticides in Latin America. University of Texas Press, Austin, Texas.

Standley, L.J. and B.W.Sweeney. 1995. Organochlorine pesticides in stream mayflies and terrestrial vegetation of undistrubed tropical catchments exposed to long-range atmospheric transport. J. N. Am. Benthol. Soc. 14:38-49.

Umańa, V. & M. Constenla. 1984. Determinación de plaguicidas organoclorados en leche materna en Costa Rica. Rev. Biol. Trop. 32(2):233-239.

Wesseling, C. and L. E. Castillo. 1992. Plaguicidas en América Central: algunas consideraciones sobre las condiciones de uso. Primera Conferencia Centroamericana sobre Ecología y Salud (ECOSAL I), San Salvador, El Salvador, 1-3 September, 1992, pp. 83-112.

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