Pesticide Residues in Coastal Tropical Ecosystems: Distribution, fate and effects - Chapter 2 ppsx

Most of the pesticides used for agricultural and other purposes are non-specific and can affect both target and non-target organisms if they reach the marine ecosystems of Ghana.. The ma

Pe s t i c i d e s i n t h e

m a r i n e e n v i r o n m e n t o f

G h a n a

S Osafo Acquaah and E Frempong

I N T R O D U C T I O N

The Republic of Ghana – formed from the merger of the British colony of the Gold Coast and the Togoland trust territory in 1957 – was the first country in colonial Africa to gain its independence It is located in western Africa roughly between Lat 5°N and 11°N, Long 1°E and 3°30'W It borders the Gulf of Guinea

in the south, Burkina Faso (Upper Volta) along its north and northwest border, the Republic of Côte d’Ivoire in the west and the Togolese Republic (Togo) in the east Ghana has a total land area of 238,540 km2 divided among 10 administrative regions: Ashanti, Brong-Ahafo, Central, Eastern, Greater Accra, Northern, Upper East, Upper West, Volta, and Western (Figure 2.1)

Ghana’s climate is warm and comparatively dry along the southeast coast but hot and humid in the southwest and hot and dry in the north There are two distinct rainy seasons in the south: April to July and September to November; however, in the north, the rainy seasons tend to merge lasting from April through September Annual rainfall ranges from about 1,100 mm in the north to about 2,100 mm in the southeast The harmattan, a dry, northeasterly desert wind, blows from December to March, lowering the humidity and creating hot days and cool nights in the north In the south the effects of the harmattan are felt primarily in January

A tropical rainforest belt, broken by heavily forested hills along with many streams and rivers, extends northward from the Gulf of Guinea, near the Côte d’Ivoire frontier This area, known as the Ashanti, produces most of the country’s cocoa, minerals, and timber North of the rainforest, Ghana is covered by low bush, park-like savanna, and grassy plains Ghana’s dominant feature is 8,482 km2

Lake Volta, which backs up behind Akosombo Dam on the Volta River, and is one

of the world’s largest artificially created lakes This lake generates electricity, provides inland transportation, and is a potentially valuable resource for irrigation and fish farming in Ghana It also provides an additional 1,125 km of arterial and feeder waterways beyond the 168 km of perennial navigation – for launches and

lighters – on the Volta, Ankobra, and Tano rivers Ghana’s coastline stretches for

539 km along the Gulf of Guinea and is mostly a low, sandy shore backed by plains and scrub It is intersected by several rivers and streams, most of which are navigable only by canoe

The country is well endowed with natural resources, e.g gold, timber, industrial diamonds, bauxite, manganese, fish, rubber, and hydropower, and has twice the per capita output of the poorer countries in West Africa Gold, timber, and cocoa production are its major sources of foreign exchange while the domestic economy continues to revolve around subsistence agriculture Agriculture, including natural resource extraction, accounts for 47 percent of Ghana’s GDP and employs 54.7 percent of the work force, mainly small landholders Ghana’s land use includes 12 percent in arable land, 7 percent in permanent crops, 22 percent in permanent pastures and 35 percent in forests and woodlands with the remaining 24 percent in other uses (1993 est.) There are also 60 km2 of irrigated farmland (1993 est.) The recent drought in the north has severely affected agricultural activities in that region However, throughout the country deforestation, overgrazing, soil erosion, poaching, Figure 2.1 Map of Ghana showing the ten administrative regions and the marine coastline

on the Gulf of Guinea

and habitat destruction threaten wildlife populations Water pollution and inade-quate supplies of potable water also pose serious problems for the approximately 19.5 million inhabitants of Ghana

Ghana is party to a number of international agreements affecting the environ-ment including the Biodiversity, Climate Change, Desertification, Endangered Species, Environmental Modification, Law of the Sea, Nuclear Test Ban, Ozone Layer Protection, Ship Pollution, Tropical Timber 83, Tropical Timber 94, and Wetlands agreements Ghana has also signed but not yet ratified the Marine Life Conservation agreement

The effect of pesticides on public health and on the environment including the tropical marine environment of Ghana are of special interest to the nation The marine environment of Ghana is polluted from a variety of sources: industrial waste effluent of several industries, e.g breweries, textile manufacturers, fish proces-sors, paint manufacturers, poultry and livestock feedmills, cement manufacturing companies, and oil refineries, located in the coastal industrial towns of Accra, Tema, Sekondi, Takoradi, and Cape Coast; discharges from the inland Lake Volta and the rivers Densu, Tano, Ankobra, and Pra; domestic sources such as sewage; agricultural activities; mining; quarrying; and others

In the past 15 years, there has been a growing interest and increased investment

in agriculture to boost food production in Ghana This has led to increased use of pesticides for the control or eradication of agricultural pests Most of the pesticides used for agricultural and other purposes are non-specific and can affect both target and non-target organisms if they reach the marine ecosystems of Ghana This chapter presents the status of pesticide pollution in the tropical marine environment

of Ghana Although some of the problems associated with the pollution of Ghana’s marine environment have been recognized, very little research work has been done

to assess the magnitude of the pollution problem and the nature of the pollutants

P E S T I C I D E L E G I S L AT I O N I N G H A N A

For many years, there was no organization or agency responsible for regulating the importation, manufacture, distribution, handling, and use of pesticides in Ghana Early attempts by some government organizations such as the Ministry of Health, Ministry of Agriculture, and the Ghana Standards Board to control the importation and distribution and use of pesticides in the country were not successful due to lack of coordination and logistics The Environmental Protection Council, now referred to as the Environmental Protection Agency (EPA), was established in

1974 as an advisory and research organization to coordinate the activities of other government bodies concerned with issues related to the environment It adopted procedures that required all importers and formulators of pesticides to seek clearance for the importation of pesticides (Environmental Protection Council, 1991) In this regard, chemicals are screened by the agency before they are imported into the country The EPA is assisted and supported by the Ghana Standards Board

(GSB), Ghana Customs, Excise and Preventive Services, Factories Inspectorate Department, and the Plant Quarantine and Regulatory Services This screening provides a form of control over the industrial chemical trade within the country and the importation of chemicals into the country

In 1994, the EPA Act (Act 490) was promulgated and, eventually the Pesticide Control and Management Bill (PCMB) was passed in 1996 The PCMB ensures

an effective monitoring of the importation, distribution, storage, sale, and use of pesticides and other hazardous substances in the country The Ghana Government enacted the PCMB to protect farmers, consumers, and the environment from harmful chemicals by ensuring quality in the manufacture of these chemicals and judicious use of these substances (particularly pesticides) Through this PCMB, the government hopes to ensure that end users are able to buy efficacious pesticides and apply them to best advantage; protect pesticide applicators, handlers, and those in contact with pesticides against the toxic effects of pesticides, especially irreversible effects; protect the general population against hazardous residues in foodstuffs; and protect the environment, especially non-target wildlife, against undesirable effects or hazards from applied pesticides

The legislation is divided into four parts and the essential provisions of each part are as set out below Part I addresses the registration of pesticides and provides for the compulsory registration, by Ghana’s EPA, of all pesticides unless a pesticide

is exempted from registration under Clause 2 Under such circumstances an unregistered pesticide may be imported for experimental or research purposes but not for general distribution, imported in the event of a national emergency, or imported only for purposes of a direct transhipment through Ghana (and it is permitted for entry into the country of destination) Part I also outlines the method for companies to apply for registration of pesticides and the mode and basis of classification of pesticides Pesticides are classified as restricted, suspended, or banned and are subject to the ‘Prior Informed Consent Procedure’, which enables the national pesticide law to be linked with internal regulations at the local district and regional levels in order to meet obligations under international trade protocols for control of pesticides and other chemical substances

Ghana’s EPA may approve and register a pesticide under such conditions as it may determine and may only register a pesticide if it is satisfied that the pesticide

is safe and effective for the use for which it is intended and that the pesticide has been tested for efficacy and safety under local conditions In addition, it has the power to ban or suspend the registration of any pesticide or cancel the registration where it is satisfied that the pesticide is not effective or may cause hazards to people, animals, crops, or the environment (Environmental Protection Council, 1991) There is also a provision for the provisional clearance of some pesticides, valid for

no more than two years, for use before registration under certain circumstances The EPA also has the authority to cancel such provisional clearance status Applicants are informed in writing of refusals to register a pesticide and the grounds for the refusal A pesticide registration remains valid for a period not exceeding two years and is renewable subject to review Ghana’s EPA maintains a registry of

pesticides with the names and particulars of registered and provisionally cleared

pesticides and publishes, annually, in the Gazette a list of registered pesticides, their

classification, and amendments made to their classifications

Part II of the legislation sets forth requirements for the licensing of dealers in pesticides, which are defined as importers, exporters-manufacturers, distributors, advertisers, and sellers of pesticides Dealers are required to obtained licenses as a prerequisite for dealing in pesticides and to keep records of their activities, retain them for 10 years, and make them available to the EPA when so required The EPA also sets out safeguards for the use of pesticides and has the power to restrict or prohibit the use of a registered pesticide in designated areas within specified periods The legislation prescribes appropriate containers, packaging, and labels for pesticides; stipulates that certain acts in relation to the adulteration of registered pesticides are prohibited; sets forth certain standards for the chemical component

of registered pesticides; and prohibits the false advertisement of registered or provisionally cleared pesticides Furthermore, it establishes a Pesticides Technical Committee of the GSB to perform pesticide control and management functions under the Bill as directed by the Board

Part III details the enforcement provisions of the PCMB and provides for inspectors and persons authorized by District Assemblies to perform the functions

of properly implementing the provisions of this law It also provides penalties for failing to comply with provisions of the law

The final part of this landmark legislation contains several general provisions that enjoin customs officers to assist in enforcement, provided that the Minister for the Environment in consultation with the Minister responsible for Food and Agriculture makes regulations for the full implementation of the law, and allowed

a 6-month grace period for registration of pesticides and issuance of licenses before sanctions could be imposed (Environmental Protection Council, 1991) Ghana’s EPA is working with other appropriate bodies to establish the necessary machinery for executing provisions of the law

P E S T I C I D E U S E I N G H A N A

For the past several decades, pesticides have been used in Ghana in the public health sector for disease vector control and in agriculture to control and eradicate crop pests However, there has been a rapid rise in the quantity of pesticides used

in agriculture over the past ten years and this growth trend is expected to continue for the next ten or more years Agricultural pesticides are used in the cocoa growing

industry (cacao tree cultivars from the genus Theobroma), for cotton farming, in

vegetable production, and for other mixed-crop farming systems involving maize,

cassava (perennial shrubs of the genus Manihot grown for the edible tubers), cowpeas (the vine-like herb Vigna unguiculata L grown for its edible seeds), sugarcane, rice,

etc The majority of pesticides used in agriculture are employed in the forest region located in the Ashanti, Brong Ahafo, western, and eastern regions of Ghana

Organochlorine pesticides are widely used by farmers because of their cost effective-ness and their broad spectrum activity Lindane is widely used in Ghana on cocoa plantations, on vegetable farms, and for the control of stemborers in maize (Ministry

of Agriculture, 1990) Endosulfan is widely used in cotton growing areas, on vegetable farms, and on coffee plantations Most of the farms in Ghana’s vegetable growing areas are situated along rivers that also serve as the water supply source for farming and for drinking water

Pesticides are also employed to control ectoparasites of farm animals in Ghana

In a study encompassing 30 organized farms and 110 kraals distributed throughout the 10 regions of Ghana, Awumbila and Bokuma (1994) found that 20 different pesticides were in use with the OC lindane being the most widely distributed and used pesticide, accounting for 35 percent of those used on farms and 85 percent

of those used by herdsmen Of the 20 pesticides, 45 percent were OPs, 30 percent were pyrethroids, 15 percent were carbamates, and 10 percent were OCs (Awumbila and Bokuma, 1994) The favorite method of application was by hand dressing and no post application interval was used before slaughter or sale of milk for human consumption (Awumbila, 1996) In this regard, there is the potential for significant risk to human health, both for the applicators and the end-users of

agricultural products Clarke et al (1997) studied the knowledge, attitudes, and

practices of 123 farm workers on three irrigation project areas in the Accra Plains regarding the safe handling and use of pesticides They found moderate levels of knowledge of pesticide absorption routes and of potential symptoms following exposure However, farm workers’ knowledge of personal protective measures was poor to moderate and their use of personal protective equipment was minimal – due primarily to financial constraints They concluded that training of agriculture and health workers in safety precautions, recognition, and management of pesticide poisoning was a matter of urgency

In the public health arena, pesticides, primarily temephos (Osei-Atweneboana

et al., 2001), have been used by the Onchocerciasis Programme in the Volta Basin

for control of black flies (Simulium spp Diptera: Simuliidae), which transmit

Oncho-cerciasis (African river blindness, a disease caused by the pathogenic nematode,

Onchocerca volvulus) to humans and for control of domestic pests, e.g cockroaches,

various flies, mosquitoes, ectoparasites including ticks, and other insects Blindness caused by Onchocerciasis is a serious and ongoing problem in this region of Africa such that the systematic treatment of most rivers across West Africa is likely to

continue for the foreseeable future However, Osei-Atweneboana et al (2001) have

found evidence for mild resistance development (slight to five-fold) to temephos in black fly populations from two sites in south-west Ghana – Sutri Rapids on the Tano River and Sekyere-Heman on the Pra River – where the larvicide had not been applied They speculate that the likely cause of resistance could have been local selection of black flies exposed to agrochemical runoff from cocoa, coffee, and palm oil plantations flanking the rivers

No detailed records have been kept on the volume and types of pesticides used

in the country, except for a few chemicals However, analysis of pesticide trade

flow patterns, recorded by Ghana’s Statistical Service, between Ghana and other countries for the period January to December 1992 and January to June 1993 indicate a total of 2,589,254 kg and 1,264,872 kg of pesticides respectively, were imported during this period (Boateng, 1993a; 1993b) Analysis of external trade statistics compiled from custom bills of entry completed by importers and exporters

or their agents show that pesticides are mostly imported rather than exported in Ghana

Analysis of the data available for the period January to December 1992 showed the following distribution of the various types of pesticides: insecticides (60.8 percent), herbicides (24.2 percent), fungicides (8.9 percent), rodenticides (1.5 percent), and other pesticide types (4.6 percent) (Boateng, 1993a) A survey conducted between 1992 and 1994 found that the following pesticides are most commonly used by farmers (in percentage of farmers using a pesticide): copper (II) hydroxide (kocide) 29.0 percent, mancozeb (dithane) 11.0 percent, fenitrothion (sumithion) 6.0 percent, dimethoate (perfekthion) 11.0 percent, pirimiphos methyl (actellic) 11.0 percent, λ-cyhalothrin (karate) 22.0 percent, and endosulfan (thiodan) 10.0 percent Lindane is widely distributed by the Ministry of Agriculture and was not included in the survey The study also indicated that insecticides constitute about 67 percent of pesticides used by farmers while fungicides made up about 30 percent and herbicides and other pesticide types were about 3 percent of total use (Osafa Acquaah and Frempong, 1995) Table 2.1 lists some of the pesticides used

in agriculture in Ghana based on a survey conducted from 1992 to 1994 in the Ashanti, Brong Ahafo, eastern, and western regions of Ghana

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 N O N

B I O T I C M AT R I C E S I N T H E I N L A N D , C O A S TA L ,

A N D M A R I N E E C O S Y S T E M S O F G H A N A

O C r e s i d u e s i n t h e i n t e r i o r o f G h a n a

Osafo Acquaah (1997) measured lindane and endosulfan in river water and fish tissues collected from rivers passing through regions of intense cocoa production and other farming activities in the Ashanti Region between 1993 and 1995 Water and fish samples from 1995 contained both lindane and endosulfan – these were the only two pesticides being investigated but chromatogram peaks corresponding

to the DDTs and other OCs were observed – with much lower levels of both pesticides present in water samples For the Oda, Kowire, and Atwetwe rivers, mean concentrations found in water samples for lindane and endosulfan were 19.4, 12.4, 16.4 and 17.9, 20.5, and 21.4 ng L–1, respectively (Osafo Acquaah, 1997) Concentrations in all the fish varied by species and month of sampling but were generally higher for lindane and much higher for endosulfan

Ntow (2001) measured OC pesticide residues in water; sediment; the tomato crop, which constitutes more than 90 percent of the major vegetables grown in the

Table 2.1 Trade names of agrochemicals, classified by use, used by farmers from the Ashanti, Brong Ahafo, eastern, and western regions of Ghana

methyl)a (atrazine) (propoxur) (foliar 20-30-10 NPK

+ micronutrients)

(cypermethrin) + cyanazine) (copper (II) oxide) (ampicillin trihydrate

–antibacterial) Desis (deltamethrin) Garlon (triclopyr, Champion (copper

a pyridine (II) hydroxide) herbicide)

(paraquat) oxychloride)

(oxadiazon) (mancozeb) Dursban (chlorpyrifos) Roundup Kocide

(glyphosate) (copper (II)

hydroxide)

(propanil) (aluminum

phosphide) Fenitrothion Basta 20 SL

(glufosinate) Fenom C (profenophos Sturnmate

+ cypermethrin) (thiobencarb)

Primigram (metolachlor

+ atrazine) Bladex (cyanazine)

Nogos (dichlorvos) Bladex (cyanazine)

Ofunack

(pyridiphenthion)

Perfekthion

(dimethoate)

Phostoxin (aluminium

phosphide)

Ripcord (cypermethrin)

Secto (lindane +

synergized pyrethroids)

Sumithion (fenitrothion)

Thiodan (endosulfan)

Trebon (etofenprox)

Gammalin 20 (lindane)

Callifan 50CE

(endosulfan)

Furadan (carbofuran)

Unden (propoxur)

Karate ( λ-cyhalothrin)

Note:

a Common names for a.i.(s) of commercial products are given in parenthesis where known.

district; and human fluids – blood samples and mothers’ breast milk – for 208 samples collected from the environs of Akumadan, a vegetable farming community located 95 km northwest of Kumasi in the Ashanti Region Aldrin, dieldrin, endrin,

2,3,5-TCB, p,p´-DDD, and p,p´-DDT were not detected in any of the samples.

However, endosulfan sulfate, α-endosulfan, β-endosulfan, and lindane were detected

in water samples taken from four area streams and a community standpipe at mean levels (frequency of detection in parentheses) of 30.8 ng L–1 (78 percent), 62.3 ng L–1 (60 percent), 31.4 ng L–1 (60 percent), and 9.5 ng L–1 (76 percent), respectively (Table 2.2) Sediment samples from the four streams contained all seven OCs, each appearing in 88 percent or more of the samples analyzed Lindane was detected at the highest level (3.2 µg kg–1) followed by HCB (0.9 µg kg–1), heptachlor epoxide (0.63 µg kg–1), and p,p´-DDE (0.46 µg kg–1) HCB and

p,p´-DDE were the only OCs detected in blood and milk and both were at lower levels

in milk than those reported in industrialized countries Ntow (2001) estimated the daily intake of DDE and HCB by nursing infants and found that consumption of both pesticides were below WHO/UNEP acceptable daily intakes

T h e G h a n a i a n c o a s t l i n e

The Ghanaian coastal zone is a part of the coastal area of the Gulf of Guinea and

is subject to some level of erosion The degree of erosion depends on the location and geology of the area of concern The coastal zone, especially around the ports

of Accra, Tema, and Takoradi, has been the major area of industrial development

in Ghana Almost 60 percent of all industries in the country are located in the Accra-Tema metropolis, which covers less than 1 percent of the total area of Ghana Along the entire coastline of Ghana, discharges into the environment are, to a large extent, untreated and unregulated, thus increasing the risk of pollution and modification to the marine environment especially in areas of high population density (Calamari, 1985; Calamari and Naeve, 1994)

T h e m a r i n e a r e a o f G h a n a

The marine area of Ghana covers about 203,720 km2 based on the 550 km stretch

of Ghana’s coastline and encompasses the area between the landward low-water mark of the coastal zone and the seaward boundary of the 200 nautical mile Exclusive Economic Zone, which is 370.4 km from shore This area is equivalent

to 85 percent of the total land area of the country

I m p a c t o f i n l a n d d r a i n a g e a n d l a n d - b a s e d

p o l l u t i o n s o u r c e s o n c o a s t a l l a n d s a n d w a t e r s

The Volta River system which, apart from its large tributaries, includes Volta Lake and the Kpong Headpond is the dominant inland drainage system in Ghana Some other major rivers, including the Tano, Ankobra, Pra, and Densu, also drain into the sea through coastal lagoons and estuaries These rivers may carry pollutants

Pesticides in the marine environment of Ghana

Ashanti Region of Ghana

Source: Adapted from Ntow, 2001.

Notes:

a dw indicates dry weight.

b fw indicates fresh weight.

c BD indicates compound detected but below detection limit of 100 ng L –1

d (<) indicates compound detected but below detection limits.

e ND indicates compound not detected.

© 2003 Milton D Taylor, Stephen J Klaine, Fernando P Carvalho, Damia Barcelo and Jan Everaarts