Pesticide Residues in Coastal Tropical Ecosystems: Distribution, fate and effects - Chapter 6 ppsx

Subsequently the Pesticide Rules, 1985, was enacted and published in the Bangladesh Gazette-Extraordinary on 16 November 1985, in exercise of powers conferred under section 29 of the Pes

>3,400 km2 and a coastline of 710 km (Matin, 1995).

Bangladesh’s economy is agriculture-based with 10 M ha under cultivation.Arable land per capita (<0.13 ha) is the world’s lowest with a cropping intensity of

159 percent (i.e land produces 1.59 crops per year), equivalent to >15 M hacultivated Agriculture contributes 35 percent to GDP and is growing at an annualrate of 1.9 percent Obviously fallow land that can be brought under cultivation isminimal in Bangladesh (less than 2 percent), and that small amount is in jeopardydue to pressure from population growth

Rice Oryza sativa L (Gramineae) is the principal food crop in Bangladesh as it is

in other South and Southeast Asian countries (Abdullah et al., 1997) Rice accounts

for about 75 percent of the total cropped area, with about 4 M ha of HYV andabout 6.7 M ha of local varieties The country is almost self-sufficient in production

of cereals but has a shortfall in many other food crops Priority at the state level isgiven to enhancing food production, especially of cereals and pulses (seed-bearingleguminous crops, e.g beans, peas, lentils), by utilizing all available means includingHYV of rice and intensive fanning practices like irrigation, improved seed, chemicalfertilizer, and pesticide application These agricultural practices have had a positiveimpact on farm productivity Bangladesh’s food grain production rose to 19.5 M

T in 1993 compared with 9.7 M T in 1967 (Rahman et al., 1995) The country is

striving for further boosts in agricultural production based on improved ment of the entire agricultural sector

manage-With respect to environmental management and agrochemical control practicesand policies in Bangladesh, the current status is disappointing with inadequateand ineffective legislation and enforcement mechanisms There is a lack ofcoordination among the various agencies involved in the protection of theenvironment; however, several national and international agencies have conductedevaluations and put forward recommendations to the government for improvement

(Coastal Environment Management, 1985; Environmental profile: Bangladesh,1989; Environment Strategy Review, 1991; National Environment ManagementPlan, 1991).

P E S T I C I D E R E G U L AT I O N

H i s t o r y o f e a r l y p e s t i c i d e l e g i s l a t i o n

Synthetic pesticides, which play an essential role as crop protection agents in modernagricultural systems, began to be used in Bangladesh (then, East Pakistan) in theearly 1950s Marketing of commercial pesticides, mainly OC and OP insecticides,was administered through government agencies and departments Under the

‘Pesticide Management Rules of Pakistan’ crop protection chemicals were uted free of cost (fully subsidized), with spraying services and equipment, duringthe years 1950 through 1971 The Pesticide Control System in Pakistan chargedthe Agriculture Extension Department with responsibility for pesticide registrationand issuing licences Guidelines for registration and the requisite enforcementmechanisms were not well developed

distrib-C u r r e n t p e s t i c i d e r e g u l a t i o n s

Bangladesh was founded in 1971 when East Pakistan split away from Pakistan.The Pesticide Ordinance, 1971, of Bangladesh was its first law regulating uses ofpesticides (Government of the People’s Republic of Bangladesh, Ministry of Lawand Justice, 1984) In its original form the ordinance is a virtual copy of the oldPakistan Pesticide Rules The Pesticide Ordinance was modified at various timesthrough 1984 to accommodate new pesticides Subsequently the Pesticide Rules,

1985, was enacted and published in the Bangladesh Gazette-Extraordinary on 16

November 1985, in exercise of powers conferred under section 29 of the Pesticide

Ordinance, 1971 (Bangladesh Gazette, 1985) These laws form the legal framework

for regulating pesticide uses and associated affairs in Bangladesh

Under the provisions of the Pesticide Ordinance, 1971 and the Pesticide Rules,

1985, a technical advisory committee advises the government on technical mattersarising out of the administration of these laws and performs any other functionsassigned to it by law The committee consists of a chairman and a number ofmembers including government officers and representatives of the pesticideindustry The Pesticide Rules Director, in the Plant Protection wing of theDepartment of Agriculture Extension, or any person authorized by him in writing,constitutes the Pesticide Registration Authority, and also functions as the PesticideLicensing Authority An analytical laboratory, still poorly organized and staffed, isalso located in the Plant Protection wing of the Department of AgricultureExtension and provides technical services for testing commercial formulations andtechnical pesticide products Field tests and efficiency trials may be required incertain cases

Government subsidization, provided during the East Pakistan period, continuedduring the early years of the Bangladesh government Changing circumstancesand economic considerations led the Bangladesh government to withdraw subsidiesbeginning in 1974, and ending them in 1979 At that time pesticide marketing wasturned over to the private sector As a consequence of the subsidy withdrawal,there was a sharp decline in consumption of pesticides However, pesticide usescontinued to be controlled by the government Then in the early 1980s, agriculturaluse of pesticides gradually increased.

Regulatory provisions describe pesticide registration licensing formalities,although how closely the regulatory mandate is adhered to is a matter of debate.Regulatory provisions are clearly inadequate and need amendment in the areas ofuse, labeling, and residues The system of regulation places emphasis on controlmechanisms, which are regrettably very poorly enforced Ideally to ensure safeand effective use of pesticides, use application and application instructions should

be evaluated by an independent scientific panel They should consider data collected

by the manufactures’ own research laboratories and other available data concerningtoxicity, persistence behavior, and the sensitivity of analytical techniques with respect

to formulated products and residues Bangladesh’s regulatory mechanisms areinadequate in this area Additionally some control must be exercised over residuelevels permitted on foodstuffs Because it is impossible to test all farm produce, thisapproach requires establishment of regulations setting residue limits If exceeded

in marketed foods, legal action can be taken against the offending farmer and thecondemned produce destroyed Such regulations are meaningless unless thegovernment employs trustworthy inspectors and analysts with an adequatelaboratory infrastructure Neither the present regulatory framework nor the enforce-ment mechanisms are currently exercised This situation must improve to ensuresafe use of crop protection chemicals

Under the regulatory provisions, the registration of a pesticide remains validfor a period of three years (until 30 June of the third year following the year ofregistration) However, the government may cancel the registration following ahearing if it believes the registration was secured fraudulently; the pesticide isineffective; or the pesticide is hazardous to vegetation (other than weeds), humans,

or animal life A license may be issued by the licensing authority to any person orbusiness intending to import, manufacture, formulate, repack, sell, offer for sale,hold in stock for sale, engage in a pest control operation on a commercial basis, oradvertise any brand of registered pesticide A license, unless suspended or canceled,remains valid for a period of two years from the date of issue and, on payment ofsuch fees as may be prescribed, may be renewed for a like period Regulationsregarding adulteration of pesticides are provided in the legal mandate Any pesticidefound to be adulterated; incorrectly or misleadingly tagged, labeled, or named; orits sale contravenes any provision of the Rules or Ordinance may be prohibitedfrom further importation by publication of a notice to that effect in the official

Gazette (Bangladesh Gazette, 1985).

PA S T A N D C U R R E N T P E S T I C I D E U S A G E

PAT T E R N S

Until recently, rice accounted for more than 80 percent of the quantity of pesticidesconsumed in Bangladesh Tea, sugarcane, and potato were next in importance,but with limited use The use of pesticides has now been extended to vegetables,oilseeds, fruits, tobacco, and other crops

Synthetic pesticides were distributed free of cost along with spraying servicesand equipment by the Agriculture Department during the l950s and 1960s Figure6.1 shows pesticide consumption for granular and conventional products since

1972 and 1973 With the lifting of subsidies beginning in 1974 and ending in

1979, there was a sharp decline in the consumption of pesticides Subsequentlyuse of pesticides increased gradually During subsidies the consumption of liquidand other conventional products were three times greater than granular products.Withdrawal of the subsidy resulted in reduced consumption of liquid productsand higher usage of granular formulations High consumption of liquid pesticideformulations in the early years of plant protection activities was primarily becausethere was free distribution of products, lending of spray equipment, and sharing

of responsibility for application by the Plant Protection wing of the Department

of Agriculture Extension During epidemics of specific pests, e.g the rice

ear-cutting caterpillar Mythimna separata Walk (Lepidoptera: Noctuidae) or rice hispa Dicladispa armigera Olivier (Coleoptera: Chrysomelidae), government applicators

conducted aerial spraying With the introduction of HYV, use of pesticides increased

Figure 6.1 Pesticide consumption in Bangladesh from 1973–95

beginning in the early 1980s The ‘Grow More Food’ campaign, beginning in theearly 1980s, also promoted increased consumption of pesticides.

Currently there is increased use of granular insecticides The reasons includeensured efficacy, a longer protection period, the scarcity of workable spray equip-ment, and ‘ready to use’ formulations About 6,000 T of granular products wereused in 1994 compared with 1,220 T liquid (EC or emulsifiable concentrate)formulations and less than 100 T soluble (SP) or wettable powder (WP) formulations

A review of the consumption of insecticides, herbicides, and fungicides finds thatBangladesh is predominantly an insecticide market (Figure 6.2) However, fungicidesand herbicides are steadily gaining market share By 1994, 500 T of fungicidesand herbicides were used annually in Bangladesh Fungicides are primarily usedfor cash crops such as potato, but fungicide use has also expanded in rice production.During 1990 to 1995, the average increase in consumption of 1 percent, 22 percentand 3 percent for insecticides, fungicides, and herbicides, respectively, was mostlydue to increased awareness of losses from diseases in field crops From Figure 6.2,

it is evident that OP and carbamate pesticides constitute about 90 percent of themarket, while OCs and other types of crop protection chemicals make up theremainder

Pesticides are used on <10 percent of cropped land with approximately 100 gma.i being applied per ha Pesticides are considered crucial for improving agriculturalproductivity and to prevent crop loss both pre- and post-harvest The annualconsumption of formulated pesticides for agriculture in Bangladesh is gradually

increasing (Matin, 1995; Rahman et al., 1995) Consumption has risen from 2,510

T in 1982 to 1983 and 5,150 T in 1988 to 1989 (Rahman et al., 1995) to 7,800 T in

1993 and just over 8,000 T in 1995 (Matin, 1995) The value of these agrochemicalswas 1 billion taka (40 taka = US$1) or US$25 M in 1993

Carbamates

OPs OCs

Figure 6.2 Distribution of pesticides classified by function and insecticides by chemical

group

Crop protection chemicals have had a positive impact on the increased

production of rice (Rahman et al., 1995) However, consumption of pesticides is

still low compared to other countries in the region The real problem with pesticideuse may be weak control mechanisms, which may result in widespread misuse andexcess application Thus, there is considerable concern about the misuse ofpesticides in Bangladesh Rice paddies, especially those planted with HYV, requirestrict pest management through the application of pesticides HYV rice is vulnerable

to various insect pests (Table 6.1) including rice hispa, stem borers Scirpophaga sp and Chilo sp (Lepidoptera: Pyralidae), plant hoppers Pyrilla perilla perpusilla Wlk.

(Homoptera: Fulgoridae) and leafhoppers (Hemiptera: Cicadellidae), the rice

ear-cutting caterpillar, rice case worm Nymphula depuunctalis Guen (Lepidoptera: Pyralidae), and the rice army worm Spodoptera mauritia Boisd (Lepidoptera:

Noctuidae) among others Consequently with such a broad array of potential insectpests to attack the HYV rice, pesticides are required for adequate control (Howladerand Matin, 1988) Per hectare consumption of crop protectants (as formulatedproducts) has gradually increased from 0.35 kg ha–1 in 1984 to 0.60 kg ha–1 in

1989 and an estimated 0.8 kg ha–1 in 1995 Generally insecticide is applied onceduring the growing season (primarily during the winter season from December toMarch), but repeated applications may be required to control pest outbreaks and

to increase the growing season of the crop

The population of Bangladesh is estimated to reach 223 million by 2030 withlittle additional land available to boost food production Presently over 10 M ha ofagricultural land are used for rice cultivation, mostly by small farmers Riceproduction, which was 9.7 M T in 1967, increased to about 20 M T in 1994through intensive farming techniques and the use of HYV rice (Matin, 1995)

Table 6.2 lists the active ingredients of pesticides registered for use in Bangladesh

Of 39 listed insecticides, 24 are labeled for rice Table 6.3 sets forth the pesticidesthat are used for rice cultivation in Bangladesh and their application rates It isapparent from the table that most rice pesticides, none of which are OCs, areinsecticides with only a few being fungicides While not registered, some persistentOCs are illegally applied because of weak regulatory controls and inadequatesurveillance programs Heptachlor, however, is registered in Bangladesh for otheragricultural purposes (sugarcane cultivation) OPs constitute the greater part ofinsecticides (60 percent); carbamates (28 percent); and pyrethroids, OCs, and others(12 percent) Of the commonly used rice insecticides, diazinon, carbofuran,malathion, chlorpyrifos, fenthion, fenitrothion, carbaryl, dimethoate, dichlorvos,and fenvelarate find wider application in rice field ecosystems Herbicides are notgenerally used for the rice paddy field although they are used for other crops such

as tea Of the 21 fungicides and 10 herbicides registered for use in Bangladeshonly three fungicides find application in the rice paddy field

Geographically Bangladesh is divided into five regions, Dhaka, Chittagong,Rajshahi, Khulna, and Barisal Pesticide consumption for each region from fourtime periods is shown in Table 6.4 For the country, per ha consumption of pesticidesgradually increased from 0.35 kg ha–1 in 1984 to 0.60 kg ha–1 in 1989 and wasestimated as 0.80 kg ha–1 in 1995 Annual consumption (kg ha–1 yr–1) of pesticides

was highest in Chittagong (having a higher population density and more extensivefarming practices) and lowest in Dhaka (land much more devoted to industrialenterprises) Because there is little additional land to boost food production for anexpanding population, multiple cropping or intensive farming practices, involvingHYV use, are necessary, thus increasing pesticide consumption from multipleapplications of crop protection chemicals.

Table 6.1 Principal pests of important crops in Bangladesh

Name of the crop Common name of the pest Scientific name

Gold-fringed borer Chilo auricilius Dudgeon White rice borer Tryporyza innotata Walker

Yellow stem borer Scirpophaga incertulas Walker Pale headed stripped rice borer Chilo suppresalis Walker Rice case worm Nymphula depuunctalis Guenée Rice ear-cutting caterpillar Mythimna separata Walker Rice army worm Spodoptera mauritia Boisduval

Wheat aphid Rhopalosiphumn rufiabdominali

Sasaki

Shoot-hole borer Xyleborus sp.

Trank borer Heterobostrychus aequalis

Waterhouse Tea mosquito bug Helopeltis sp.

Jute Jute hairy caterpillar Diacrsia obliqua Walker

Jute semi-looper Anomis sabulifera Guenée Jute stem weevil Apion corchori Marshall Sugar cane Top shoot borer Scirpophaga monostigmata

Zeller Stem borer Scirpophaga exerptralis Walker Sugar cane top shoot borer Scirpophaga auriflua Zeller Sugar cane stem borer Chilo tumidicostalis Hampson Leafhopper Pyrilla perilla perpusilla Walker

Leaf caterpillar Chaetochema cohcicpennis

Bally Gram weevil Alcides colloris P.

Azuki bean weevil Callosobruchus chinensis L.

Fabricius Stored grains Rice weevil Sitophilus oryzae L.

(rice and wheat) Angoumois grain moth Sitotroga cerealella Olivier

Red flour beetle Tribolium castaneum Herbst Grain weevil Sitophilus granarius L.

Depressed flour beetle Palorus subdepressus Wollaston

P E S T I C I D E R E S I D U E S I N B I O TA A N D A B I O T I C

M AT R I C E S

Pesticide residues originate from application of the formulated a.i.(s) to crop fieldsand may be transported offsite through spray drift and runoff aided by rain, floods,tidal surge etc (Hassall, 1990) Consequently contamination of canals, ponds,

Table 6.2 List of registered pesticides (a.i.) in Bangladesh

Copper oxychloride Aluminum phosphide

rivers, and other waterways with residues of the parent compounds or their tion products is possible (Rahman, 1995) Furthermore, food harvested from theapplication sites and elsewhere may be contaminated with residues (Rahman, 1995).Fish cultured or living in the fields or nearby and fish in downstream waterways

degrada-can be affected by toxic residues (Abdullah et al., 1997) Fish are the major

non-target species adversely affected by application of hazardous pesticides (Abdullah

et al., 1997) Populations of both flora and fauna have been reported to be

Table 6.3 Pesticides recommended (registered) for rice fields in Bangladesh with

experiencing significant declines due to application of pesticides in Bangladeshand elsewhere (Hassall, 1990) Many other undesirable side-effects may appear inthe aftermath of repeated pesticide application (Hassall, 1990; Rahman, 1995).Organochlorine and pyrethroid insecticides, in general, may cause damage to fishand other non target species (Hassall, 1990).

In Bangladesh a complete risk assessment of the use of pesticides, especially inthe rice paddy ecosystem, has yet to be made Scattered published reports coupledwith some preliminary findings (since 1992) by the Institute of Food and RadiationBiology of the Bangladesh Atomic Energy Commission suggest misuses of cropprotection chemicals in Bangladesh This is due to a lack of or inadequateenforcement of regulatory measures Unregistered compounds find application in

agriculture due to poor enforcement of the relevant law by authorities (Matin et al., 1995) Unlawful use of DDT to treat pest infestations in dried fish has been detected and residue levels were found to be high (IAEA, 1995; Matin et al., 1995).

In subsequent studies using dried fish treated with 14C- DDT, Matin et al (1996)

found that, luckily for consumers, most of the applied DDT remains on the surface

of the sun-dried fish and also that most of the residue could be eliminated duringpre-cooking processing using traditional household preparation techniques (Figure6.3)

Table 6.4 shows the range of pesticide residues (including toxic metabolites)measured in food and environmental samples from Bangladesh Although OCinsecticides are not registered, residues are found in different components of the

Pesticides in Bangladesh