ASSESSMENT OF RISK CONNECTED IN THE MANAGEMENT OF ... · 132 oxydability by determination of permanganate index with KMnO. 4. (NF- EN ISO 8467). 133 . 2.3.2 Bacteriological analyses

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* Corresponding author: AISSI K. Alain, Mobile : 00(229) 95784471, 04 BP 312, Cotonou, Benin [email protected]

*Original Research Paper 1

2

ASSESSMENT OF RISK CONNECTED IN THE 3

MANAGEMENT OF EFFLUENTS FROM 4

ABOMEY-CALAVI AND SO-AVA 5

LABORATORIES 6

Alain K. AISSI*a,b , Patrick A. EDORHb,e , Cyriaque DEGBEYc, Patient 7

GUEDENONb, Julien SEGBOd , Armelle S.Y. HOUNKPATINb ., Michel 8

BOKOb, Frédéric LOKOd 9

10 a Biomedical Laboratory of the Regional Hospital of Abomey-Calavi and Sô-Ava Area, BP 11

1709 Abomey-Calavi, Benin 12

b Laboratory of Toxicology and Environmental Health, Interfaculty Centre of Training and 13

Research in Environment for the Sustainable Development, University of Abomey-Calavi, 03 14

BP 1463, Jericho, Cotonou, Benin 15

c Health Unit at work place and Toxicology of Environment, School of Public health, Campus 16

Erasme, CP-593, Road of Lennik, 800, 1070 Brussels, Belgium. 17

d Research Laboratory in Applied Biology, Department of Human Bioengineering, 18

Polytechnic School of Abomey-Calavi, University of Abomey-Calavi, 01 BP 2009, Cotonou, 19

Benin 20

e Department of Biochemistry and Cellular Biology, University of Abomey-Calavi (UAC), 01 21

BP 526, Cotonou, Benin. 22

23 24

25 26 27 .28

* Corresponding author: AISSI K. Alain, Mobile : 00(229) 95784471, 04 BP 312, Cotonou, Benin [email protected]

29

30

31

32

ABSTRACT 33

A study was conducted in four sanitary training units of Abomey Calavi and Sô-Ava area to assess the risks connected to effluents released by laboratories performing biomedical analyses. The data were obtained based on an observation bar of the sites, by interviewing the participants and by analysing the discharged liquid of laboratories as well as the ground waters (wells, drillings) situated near pits and other places used for discharging biomedical effluents. The results revealed a mismanagement of biomedical effluents. In respect of the physico-chemical characteristics of the effluents, the mean values of pH ranged from 7.17 to 8.83; the values of temperature recorded in the present investigation were lower than 30°C and are in accordance with the standards of discharges. The mean values of conductivity exceeded the acceptable limits in 75 % of the cases (2000 to 4260 µS / cm). The COD of sewage rose from 201 to 3400 mg / L and were in strong correlation with the BOD5 (r

2 = 0.998) whose values ranged between 150 and 1700 mg / L. The contents in

nitrogen (38.4 - 97.5 mg / L) and in phosphates (11.8 to 30 mg / L) exceeded the standard limits which are 30 and 10 mg/L respectively. Besides, important quantities of faecal Coliforms exceeding 100x10

3 CFU / 100mL were recorded in 75 % of the

analyzed effluents. This explains the ineffectiveness of the decontamination carried out by the staff. The examination of well waters and water from the drillings situated near pits serving laboratories showed high turbidity (20 to 91,1 NTU), low rates of dissolved oxygen (< 5mg / L) and indications of bacterial contamination (160 CFU of Escherichia coli / 100mL in water). The results suggest a connection between biomedical activities and groundwater pollution. This issue poses a real problem of public health because of the infectious, toxic and eco-toxic risks for the population and it is important to find a sustainable solution

34

Keywords: Laboratories, Effluents, Risk, Environment, Health. 35 36

1. INTRODUCTION 37

The management of biomedical effluents constitutes one of the challenges for the 38 Sustainable Development. In Benin, the comparative analysis of the effluents at the inlet and 39 outlet of the Purge Station of the biggest national hospital showed the inefficiency of the 40 chemical and biological treatment (Makoutodé, 2002). According to Gartiser et al (1996) and 41 Kummerer et al (1999), certain compounds such as organo-halogenated and medicinal 42 residues are often released directly from purge systems without pretreatment. Indeed, if 43 done without precaution, the discharges of products stemming from maintenance activities, 44 from radiology or biomedical analyses pollute ground, ground water and nearby surface 45 water. This pollution poses toxicological and infectious risks for human health. Approximately 46 2 in 9 % of seroconversions in hepatitis B, C and in HIV could be connected to contact with 47 blood residues or soiled trash cans (Coulibaly et al, 2010). Infections with Mycobacterium 48 tuberculosis (Johnson et al, 2000), enterovirus, and Legionella pneumophila, with prion 49

(Gregersen et al, 1999), with Salmonella or endotoxins (Thorn, 2001) were found in 50 employees or animals that were in direct contact with the waste. As a rule, according to the 51 Regulations referring to rational management of biomedical waste “any hospital effluent 52 must be pre-processed before being released in the environment or poured in the public 53 network of purification (DHAB, 2002). Regrettably, following the example of most of the 54 sanitary structures in West Africa (Sanogo et al, 2007), these Regulations are not respected 55 in Abomey-Calavi and Sô-Ava area in the South of Benin Republic. Therefore Thie present 56 study aims at assessing the risks connected in the management of the biomedical effluents 57 from laboratories of Abomey-Calavi and SO-AVA. 58

2. MATERIAL AND METHODS 59

2.1 STUDY AREA 60

This study was led in the Sanitary Area (operational decentralized entity of health system) of 61 Abomey-Calavi and Sô-Ava from March 2

nd to August 31

st, 2010 for a period of 6 months. 62

The health system of Benin is organised as a pyramid scheme on three levels. The central 63 level or the apex of the scheme belongs to the Health Ministry with hospital complexes of 64 National Reference. The side levels include health departmental offices (six in number at the 65 rate of one office for two departments) whereas the base of the scheme consists in 34 66 sanitary areas gathering into 2 or 3 districts of the country. The sanitary area is the 67 operational decentralized entity of health system. It coordinates the most accessible sanitary 68 units (health centres, clinics, maternity hospitals, isolated community clinic, village health 69 units) depending on a top reference health centre or on a regional hospital. 70 Thus, Abomey-Calavi and Sô-ava (two districts) form a Sanitary Area situated in the South 71 of Benin (Figure 1). Its area measures 868 km

2 with a cosmopolitan population of 513160 72

inhabitants. It accounts 18 public sanitary points and more than 200 private ones (Statistical 73 Service, 2008). The relief is little bumped in Calavi and the climate of subequatorial type. 74 Grounds are ferruginous, sandy or hydromorphic by place. 82 % of Sô-Ava territory is 75 lakeside. Recent studies in its main lake (Nokoué) report a strong contamination by heavy 76 metals (lead, Cadmium) whose sources were yet to be identified (Edorh et al., 2010; Kaki et 77 al.2011). In Calavi, the majority of the domestic well-water is polluted (Degbey et al, 2008). 78 79 80 81

82

83

Figure 1: Location Map of the84

85 86 2.2 SAMPLING AND DATA COLLECTION87

Four laboratories were reasoned88 frequentation and registration of the 89 techniques used were direct observation through90 through questionnaires of 26 personnel chosen accordi91 and management of effluents. They are labor92 nurses, maintenance agents involved in laboratory activities, technicians in charge 93 hygiene, unit head doctors, human and material resources managers, inhabitant delegates 94 having a well located at less than95 effluents. 96

Geographical coordinates were taken with the help of GPS Garmin at several levels. 97

A pre-inspection allowed us to 98 particularly the evacuative circuit from labo99 released in the sinks (picture 1) go through an underground100 behind the building (picture 2) to end in a rounded shaped catch basin (picture 3) 101 close to rectangular shaped 102 sink cross no purge system 103 made of concrete, these are the true samples of laboratory 104

105

the Sanitary Area of Abomey-Calavi and Sô-Ava

AND DATA COLLECTION

Four laboratories were reasoned-way selected on the basis of important criteria such and registration of the centers on the list of the Statistical Service. The

e direct observation through regular visits of the sites and interviews through questionnaires of 26 personnel chosen according to their implications in production

management of effluents. They are laboratory staff, laboratory technicians, auxiliary nurses, maintenance agents involved in laboratory activities, technicians in charge hygiene, unit head doctors, human and material resources managers, inhabitant delegates having a well located at less than 75 m from the pits and discharged channels of laboratory

Geographical coordinates were taken with the help of GPS Garmin at several levels.

inspection allowed us to assess precisely the drainage network in each sanitary unit, circuit from laboratories. This inspection proved that the

(picture 1) go through an underground pipe and crossbehind the building (picture 2) to end in a rounded shaped catch basin (picture 3)

rectangular shaped septic tanks. Considering the fact that liquids draining from the before infiltrating into the ground through the catch basins not

made of concrete, these are the true samples of laboratory effluent.

on the basis of important criteria such as the Statistical Service. The

sites and interviews ng to their implications in production

atory staff, laboratory technicians, auxiliary nurses, maintenance agents involved in laboratory activities, technicians in charge of hygiene, unit head doctors, human and material resources managers, inhabitant delegates

75 m from the pits and discharged channels of laboratory

Geographical coordinates were taken with the help of GPS Garmin at several levels.

precisely the drainage network in each sanitary unit, ratories. This inspection proved that the effluents

a manhole behind the building (picture 2) to end in a rounded shaped catch basin (picture 3) located

septic tanks. Considering the fact that liquids draining from the before infiltrating into the ground through the catch basins not

Picture 1: Sinks through which

effluents are drained in the laboratory of the hospital of

Abomey-Calavi 106

Since these effluents stored in the 107 are permanent and hermetically 108 sinks were blocked from 8 a.m in order to gradua109 chemical treatment carried out 110 collected samples of the composite liquid using a plastic jar of 1.5 L (picture 4,5).111

112

Picture 4: Discharge of soaking liquids from washing materials in

that was blocked before

113

Besides, well-waters from nearby114 were collected. Sampled waters115 transported to the national hygiene and 116

117

118

re 1: Sinks through which effluents are drained in the laboratory of the hospital of

Picture 2: Fix manhole under which the sink pipe passes to end in the catch basin

Picture 3: Catch basin a receptacle of

stored in the catch basins are inaccessible because the catch basins are permanent and hermetically closed, we proceeded in the following manners: At first, sinks were blocked from 8 a.m in order to gradually collect the drained liquids after a

carried out by the laboratory personnel. Later, every 2 hourssamples of the composite liquid using a plastic jar of 1.5 L (picture 4,5).

Discharge of soaking liquids from washing materials into the sink

that was blocked before

Picture 6: collection of laboratory effluents

samples from the sink with a plastic jar

waters from nearby pits and from other places of biomedical waste dcollected. Sampled waters were carefully labeled, preserved in iceboxes and

ygiene and basic purification Laboratory (NHBP).

Picture 3: Catch basin serving as

a receptacle of laboratory effluents

are inaccessible because the catch basins closed, we proceeded in the following manners: At first,

lly collect the drained liquids after a by the laboratory personnel. Later, every 2 hours, we

samples of the composite liquid using a plastic jar of 1.5 L (picture 4,5).

Picture 6: collection of laboratory effluents samples from the sink

a plastic jar

places of biomedical waste disposals preserved in iceboxes and

2.3 METHODS OF ANALYSIS 119

120

2.3.1 Physico-chemical analyses 121

The French Standards (NF) published by the French Association of Standardization (1997) 122 served as reference for the analyses of water and effluents. pH, temperature and dissolved 123 oxygen were measured with the help of a multimeter WTW pH / oxi 340i. The references are 124 NF T 90 - 008) for pH and NF EN 25814 for dissolved oxygen. The conductivity was 125 measured by means of a conductimeter WTW Cond 340i (NF EN 27888). The values of 126 turbidity were recorded by means of a turbidimeter HACH 2100 P using the NF - EN 27027) 127 guidelines. The COD, Kjeldahl nitrogen, total phosphor, nitrate (NO

3-), nitrite (NO

2-), 128

ammonium (NH4+), orthophosphate (PO4

3-), were measured after mineralization by 129

Molecular Absorption Spectrophotometer (HACH DR 2800) according to the AFNOR 130 standards. The BOD5 was measured by respirometric method (NF T 90 - 10

3) and the 131

oxydability by determination of permanganate index with KMnO4. (NF- EN ISO 8467). 132

2.3.2 Bacteriological analyses 133

The enumeration of micro organisms was carried out by counting the colonies obtained in 24 134 hours after culture at 44°C on Rapid E. Coli (NF V - 08 - 05) agar. This agar is selective and 135 allows the distinction of Escherichia Coli among all the faecal coliforms. Its preparation was 136 carried out in accordance with the manufacturer guidelines and maintained melted at 47°C 137 until the moment of its use. The culture was realized by mixing 5 ml of each sample (not 138 diluted) followed by successive dilutions of these samples into different Petri dishes carefully 139 labeled. It is important to state that all this was performed close to the flame of Bunsen 140 gaslamp to avoid all kind of contamination. 20 minutes later, 15 - 20 ml of prepared agar was 141 spilled on the innocula and carefully mixed. The mixture was left on the laboratory bench top 142 until solidification. Finally, the dishes were placed in an oven at 44°C. After 24 hours, the 143 pink (Escherichia Coli) and blue (other Coliform) colonies were counted. The results were 144 expressed in CFU/100 mL. 145

2.4 DATA PROCESSING 146

Statistical analyses were carried out using SPSS version 16.0. The comparisons of the 147 different means with standards were performed with the help of students test. The difference 148 is significant if p < 0. 05. The maps were drawn using Arc-Gis software. 149

150

3. RESULTS AND DISCUSSION 151

152

3.1 RESULTS 153

3.1.1 Typology of the chemical and biological products observed in laboratories 154 during our inspection 155

Blood, urines and human stools were the most biological analyzed. The examination of pits 156 was carried out only in Calavi health centre and in the Hospital of Sô-Thanhoué. The bleach 157 was the most used disinfectant. 158

The colouring agents of Gram and Giemsa existed everywhere whereas Zielh A and B were 159 used only in Calavi health centre and in the Hospital of Sô-Thanhoue. According to their 160 indications on the specification sheet, the kits of reagent contained a variety of chemical 161 substances such as: conservatives (azide of sodium), enzymes (oxidases, peroxidases, 162 phosphatase), amino or phosphated elements (nitrite, diethylamine, 4-amino-antipyrine, 163 phosphates tampon), acids, base and others (cyanomethemoglobin, cyanide, 164 dimethylsulfoxide, etc.). All these items were observed in the laboratories during our 165 inspectoral investigation. We specify that no specific analyse was done in this study to look 166 for these chemical substances in the samples. 167

3.1.2 Opinion poll about the Management of the effluents from laboratories 168

Eleven staff out of 17 i.e. 64.7 % were used to throwing back the blood products in sinks. 169 88.2 % acted the same way to eliminate liquids stemming from chemical reactions. At the 170 Regional Hospital and at Calavi health centre, the final destination of the blood products was 171 a pit lost in the far end of a corner in the courtyard (Table 1). The incompletely used, expired 172 or spoilt reagents were incinerated, buried, or simply poured on the garbage dumps of 173 general waste. Till now, no laboratory has set written procedures on biomedical wastes 174 management. The directives of sorting and separation of the wastes at the source were not 175 actually respected. The dilutions of the bleach were made by guesswork and the period of 176 contact needed for ensuring a complete decontamination was not standardized. Six agents 177 out of 25 questioned, i.e. 24 % stated they were dissatisfied with the management of the 178 liquid waste in their institution. 179

180

181

182

Table 1: Final destination of the liquid discharges by laboratory 183

Types of waste Regional

Hospital of Calavi

Health centre of

Calavi

Hospital of Sô-

Tchanhoué

Health centre of Sô-Ava

Blood products - bottomless pit

- pit via sink - bottomless pit

- pit via sink pit via sink pit via sink

Saddles, spit, rest of reagent that are damaged or made obsolete

incinerator or garbage dump

Bottomless pit incinerator or garbage dump

Bottomless pit

Urines, the other biological liquids, residual liquids of the reactive processes, coloring, detergent, etc.,

pit via sink

pit via sink

pit via sink

pit via sink

Source: Ground investigation. 184 185 186

3.1.3 Exposure and prevention measures of the risks in the laboratories 187

The agents were aware of infectious (17/17), toxic (15/17), ecotoxic and carcinogenic 188 (14/17) risks that the laboratory effluents posed. The most frequent modalities of exposure 189 were: the spatter and the inhalation during the carrying out of the laboratory analyses or 190 during the discharge of soiled liquids (9/17). The vaccination of the staff exposed to hospital-191 borne infections (viral B hepatitis in particular) and the trainings on the management of risks 192

connected to the wastes didn’t follow the guidelines set by World Health Organization 193 (WHO). 194

3.1.4 Physico-chemical and bacteriological characteristics of the effluents 195

3.1.4.1 Results of the parameters measured in situ 196

The results are presented in table 2. The average pH of the effluents measured in 197 laboratories ranged from 7.17 to 8.83. The average temperatures ranged between 28.0 and 198 29.7°C. The average conductivities at the Regional Hospital (3700 µS / cm) and in Calavi 199 health centre of (4260 µS/cm) exceeded the acceptable standards. The average contents of 200 dissolved oxygen were lower than 5 mg/L in all locations. 201

202

Table 2: Comparison of the parameters measured in situ with the acceptable 203 standards for effluents samples obtained from sink 204

Parameters Regional Hospital of

Calavi

Health centre of Calavi

Hospital of Sô-

Tchanhoué

Health centre of Sô-Ava

Acceptable Standard

Hydrogene Potential (pH)

pH 1 9,12 9,17 8,00 7,87

6 à 9

pH 2 10,55 6,09 7,18 9,21 pH 3 7,48 9,54 10,09 7,66 pH 4 8,17 9,32 3,41 8,74 Mean pH 8,83 8,53 7,17 8,00 Std deviation 1,329 1,634 2,790 0,730

Temperature (T°) in °C

T° 1 28,0 28,7 28,0 28,0

< 30

T° 2 28,9 28,9 30,0 27,0

T° 3 30,0 28,0 28,7 28,0

T° 4 29,9 33,2 25,3 29,8 Mean T° 29,2 29,7 28,0 28,2 StD 0,942 2,365 1,982 1,166

Conductivity (Cond) in µS/cm

Cond 1 3100 3300 500 1960

< 2000

Cond 2 3760 4100 400 1380

Cond 3 3880 4900 102 3480 Cond 4 4060 4740 586 3100

Mean Cond 3700 4260 397 2480 StD 210,84 977,20 418,56 727,36

Dissolved oxygen (O2) in mg/L

O2 1 4,77 3,07 2,43 4,30

> 5

O2 3 5,00 4,10 4,51 3,73

O2 3 3,93 4,43 2,00 4,03 O2 4 4,02 5,00 3,46 4,74 Mean O2 4,43 4,15 3,1 4,2 StD 0,534 0,810 1,121 0,428

StD = Standard deviation 205 Source: ground investigation 206

207 208

209

3.1.4.2 Results of the parameters measured in laboratory 210

The mean concentrations of the BOD5 ranged from 150 to 1700 mg/L and were all higher 211 than the standards fixed to 50 mg/L. The average COD ranged between 201 to 3400 mg/L. 212 The average content of nitrogen (34.5 mg/L) and of total phosphor (97.5 mg/L) exceeded the 213 limits fixed which are respectively 11.88 mg/L and 30 mg/L (Table 3). The pool of effluents 214 analyzed in Calavi health centre did not contain faecal coliforms. At the Hospital of Sô-215 Tchanhoue, the effluents were strongly contaminated with Escherichia coli (688 X 10

3 216

CFU/100mL) whereas at the Regional hospital and at the health centre of Sô-Ava, colonies 217 of the other types of coliforms faecal were 128 X 10

3 and 102 X 10

3 CFU/100mL 218

respectively). 219

220

Table 3: Comparison of the means of the parameters not measured in situ with the 221 standards 222

Parameters Unit Regional Hospital of

Calavi

Health centre of Calavi

Hospital of Sô-

Tchanhoué

Health centre of Sô-Ava

Acceptable Standard

BOD5 mg/L 1700 330 150 430 < 50

COD mg/L 3400 764 201 876 < 200

Nitrogen NTK mg/L 97,5 78,7 38,4 34,5 < 30

Total Phosphor mg/L 30 11,8 30 20 < 10

Faecal Coliforms CFU /100mL 128.103 0 688.10

3 102.10

3 < 2.10

3

Faecal Coliforms CFU /100mL 0 0 688.103 0 < 1

Source: ground investigation 223 224

225

3.1.5 Physico-chemical and bacteriological Characteristics of the surrounding 226 groundwater nearby the inspected laboratories 227

228 The turbidity of waters from the well (20 NTU) and from drilling (91.1 NTU) was highly above 229 the standards of potability (5 NTU). The content of dissolved oxygen was low in samples. 230 The concentrations in nitrite, nitrate, ammonium and orthophosphate were in accordance 231 with the WHO limits. The water of the drilling had a higher oxydability (8 mg/l of 02) than the 232 standard but was exempt from faecal coliforms contrary to the water of the well which 233 contained 3.92.10

3 CFU/100mL among which 0.160. 10

3 Escherichia coli (Table 4). 234

235

236

237

238

239

Table 4: Comparison of the averages of the physico-chemical and bacteriological 240 parameters of waters from the well and from drilling with the standards of drinkability 241

Parameters Unit Well in Health Centre of

Calavi

Drilling in Hospital of Sô-

Tchanhoué

Acceptable Standard

pH - 4,7 6,53 7- 8,5

Temperature °C 26 25 < 30

Conductivity µS/cm 202 218 < 2000

Turbidity NTU 20 91,1 < 5

Salinity ‰ 0 0 0

Dissolved oxygen mg/L 3,28 3,82 ≥ 5

Robust dissolved totals mg/L 203 209 < 1000

Oxydability mg/l de 02 0,54 8 < 5

Nitrite NO2- mg/L 0,052 0,072 < 3

Nitrate NO3- mg/L 30,48 13 < 50

Ammonium NH4+ mg/L 0,13 0,15 < 0,2

Orthophosphate PO43-

mg/L 0,26 0,37 < 5

Faecal Coliforms CFU /100mL 3,92.103 0 < 2

Escherichia coli CFU /100mL 0,160.103 0 0

Source: ground investigation 242 243

244

3.2 DISCUSSION 245

3.2.1 Management of the liquids effluents in laboratories 246

The directives of sorting and separation of the effluents at the source were not properly 247 respected in the laboratories of the Sanitary Area of Abomey-Calavi and Sô-Ava contrary to 248 the laboratories of Abidjan (Coulibaly et al, 2010). One of the causes of this negligence was 249 lack of harmonization in the practices of wastes management which should comply with 250 18189 ISO guidelines. Most laboratories have the habit to throw the effluents in pits via sinks 251 or directly in holes dug in a corner which triggers the risk of transfer of biomedical pollutants 252 in aquifers (Canivet and Fruget, 2002). The outdoor incineration of the biomedical wastes is 253 also a bad process (N'Diaye et al. 2003; Billau, 2008). If the bactericidal and virucidal 254 potential of bleach is worldly renowned (Mansotte et al. 2000), its efficiency in the 255 decontamination of effluents depends on several factor such as: rate of dilution, the duration 256 of conservation of the diluted liquid and the period of contact with the material to be 257 disinfected (Billau, 2008; WHO, 2010). It was observed in most of the laboratories that the 258 staff made random dilutions and rarely observed suitable wait-time for the disinfection to be 259 efficient resulting in triggering potential risks of infection. 260

261

3.2.2 Risk management in the inspected laboratories 262

Though most of the workers were aware of the threat posed by the biomedical effluents, they 263 didn’t comply with safety instructions. Those who did not regularly wear gloves justified their 264 behavior either by lack of subsidies in terms of protection, lack of ideal behavior from their 265 immediate superiors who also didn’t comply with safety instructions, or discomfort caused by 266 the wearing of gloves. These reports showed the social influence of the individual 267 psychological perceptions and of the social background on the attitude of the individuals 268 facing the daily professional danger. That is why Coppieters et al. (2004) suggest the 269 integration of a psycho-sociological approach in the assessment of risks. The viral hepatitis 270 B and C are classified among the first five professional diseases in a hospital environment 271 (SGERN, 2000) and the vaccination recommended for the staff at risk (WHO, 2010) was not 272 organized in spite of the high rates of accident of exposure to blood (29 % found in the 273 visited laboratories) following the example of prevalence (39 %) reported by Zannou et al. 274 (2006). 275

3.2.3 Quality of the biomedical effluents stemming from laboratories 276

The temperature of the effluents (lower than 30°C) showed that there was no thermal 277 pollution. The high values of conductivity (> 2000 µS / cm) in 75 % of the effluents proved 278 the abundance of mineral elements as reported by Emmanuel (2003) and Belokda (2007). In 279 the National University Hospital Centre (NUHC) of Cotonou, Makoutodé et al (2002) had 280 also found high conductivities ranging from 3200 to 5320 µS/cm with average pH of 7 and 281 temperatures lower than 30°C in effluents. In respect of the oxidizing materials, 75 % of the 282 COD exceeded the limit of 200 mg / L fixed in Senegal (NSI, 2001) and in Morocco 283 (Belokda, 2007). The recorded COD values exceeded the American standard (150 - 800 284 mg/L) fixed by the Environmental Protection Agency (Emmanuel, 2003). High values (450 285 mg/L, 1095 mg/L, 510 mg / L and 1940 mg / L) were respectively found in the NUHC of 286 Cotonou (Makoutodé, 2002), in the Regional University Hospital Centre of Limoges (Darsy et 287 al, 2002), at the hospital of Port-au-Prince (Emmanuel, 2003) and at Mohamed V’s hospital 288 of Safi (Belokda, 2007). The high values above ISN standards (NSI, 2001) - in terms of 289 nitrogen and phosphor - could be a threat especially to the lakeside villages (Sô-Ava and Sô-290 Tchanhoué). In fact nitrites are dangerous poisons for the aquatic organisms, even in low 291 concentrations (Tarmoul, 2007). By degrading haemoglobin, which becomes inapt of 292 transporting the oxygen they can cause the death of fish by asphyxia (Tarmoul, 2007). 293 Sometimes, nitrites are transformed into nitrates which contribute to the eutrophication 294 (Emmanuel, 2003; Tarmoul, 2007). The proliferation of faecal coliforms during the bacteria 295 culture in 75 % of the effluents put to doubt the quality of the decontamination carried out in 296 laboratories. This ineffectiveness of treatment by chlorination was also noticed by 297 Makoutode et al (2002) in the NUHC who observed more than 103 CFU colonies of faecal 298 coliforms in 100 ml of effluent after treatment. 299

3.2.4 Analyses of the impact of the biomedical effluents on groundwater 300

According to the model of rise in the ground (Figure 2), the shallow depth of groundwater at 301 the level of Sô-Ava (4 m) and Sô-Tchanhoué (5 m) makes them more vulnerable to 302 biomedical pollutants compared to Calavi (13 m of depth at the level of the health centre and 303 about 19 m in the local hospital). The pollution of the groundwater in Calavi was in 304 agreement with the findings of Degbey et al (2008) who stated that 100 % of wells in this 305 locality contain germs (Escherichia coli, faecal Streptococci, Salmonellas, Shigellae, 306 Clostridium perfringens, Staphylococci) as well as nitrites, iron and manganese. Among the 307 potential sources of this pollution and in spite of the complexity of the mechanisms of 308 circulation of pollutants in aquifers (Emmanuel, 2003), the strong contribution of biomedical 309 activities could be suspected. 310

311

312

Figure 2: Model of rise in the ground of the study area313

HZ = Regional Hospital ; 314 315 316 317

318

4. CONCLUSION 319

The results obtained prove that effluents stemming from biomedical laboratories of Abomey320 Calavi/Sô-ava Sanitary Zone present infectious, toxic, eco321 management could be better ensured particularly by an eco322 health. This risk assessment could be deepened by epidemiological inquiries (calculation of 323 risk index within the staff and the exposed populati324 The mechanisms of transfer of persistent pollutants (heavy metals, residues of AOX, etc.) 325 should be analyzed and preventive actions such as public means of raising awareness 326 should be carried out. 327

328

329 330 331 332

Model of rise in the ground of the study area

HZ = Regional Hospital ; CS = Health Center

Source: ground investigation

The results obtained prove that effluents stemming from biomedical laboratories of Abomeyava Sanitary Zone present infectious, toxic, eco-toxic risks. Consequently, their

management could be better ensured particularly by an eco-systemic approach to human health. This risk assessment could be deepened by epidemiological inquiries (calculation of risk index within the staff and the exposed populations) and specific toxicity tests as well. The mechanisms of transfer of persistent pollutants (heavy metals, residues of AOX, etc.) should be analyzed and preventive actions such as public means of raising awareness

The results obtained prove that effluents stemming from biomedical laboratories of Abomey-risks. Consequently, their

systemic approach to human health. This risk assessment could be deepened by epidemiological inquiries (calculation of

ons) and specific toxicity tests as well. The mechanisms of transfer of persistent pollutants (heavy metals, residues of AOX, etc.) should be analyzed and preventive actions such as public means of raising awareness

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DEFINITIONS, ACRONYMS, ABBREVIATIONS 404

AFNOR French Association of Standardization 405

AOX : Organo-halogenated compound absorbable on charcoal 406

BOD5 : Biochemical Oxygen Demand for five days 407

CFU : Colony Forming Unit 408

COD : Chemical Oxygen Demand 409

DHBP : Direction of Hygiene and Basic Purification 410

GPS : Geographic Position System 411

ISO : International Standardization Organisation 412

HIV : Human immunodeficiency Virus 413

NSI : Normalization Senegalese Institute 414

NTK : Kjedahl Nitrogen 415

NTU : Nephelometric Turbidity Unit 416

NUHC : National Universitary Hospital Centre 417

pH : Hydrogen Potential 418

WHO : World Health Organization 419

°C : Celsius degree 420

SGERN: Study Group on the Exposure Risks of Nurses 421

WTW : Wissenschaftlich Technische Werkstutten. 422

423 424

425

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