ISABB Journal of
Health and Environmental Sciences

  • Abbreviation: ISABB J. Health Environ. sci.
  • Language: English
  • ISSN: 1937-3236
  • DOI: 10.5897/ISABB-JHE
  • Start Year: 2011
  • Published Articles: 14

Full Length Research Paper

Environmental and health impact associated with the dissemination of persistent organic pollutants (POPs) in Yaoundé

NANFA Dieudonné*
  • NANFA Dieudonné*
  • Department of Biochemistry, University of Yaounde 1, Cameroon.
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Ndonwi E Ngwa
  • Ndonwi E Ngwa
  • Biotechnology Centre, University of Yaounde 1, Nkolbisson, Cameroon.
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Donfack S Olivier
  • Donfack S Olivier
  • Biotechnology Centre, University of Yaounde 1, Nkolbisson, Cameroon.
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FOPA L. G. Bertrand
  • FOPA L. G. Bertrand
  • Training School for Nurses and Health Technicians, Yaounde, Cameroon.
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ATOGHO T. Barbara
  • ATOGHO T. Barbara
  • Biotechnology Centre, University of Yaounde 1, Nkolbisson, Cameroon.
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  •  Received: 06 January 2015
  •  Accepted: 17 March 2015
  •  Published: 30 March 2015


Cameroon signed in 2001 and ratified in 2005, the Stockholm convention which aimed at restricting and eliminating the production, utilization and discharge of persistent organic pollutants (POPs). Since then, the implementation of this convention in countries is not effective despite the perceptive diffusion of this toxic chemical substance. Few studies on the diffusion of POPs and risks attached to it have been carried out in Yaoundé. Thus, the aim of this study was to search the measures to limit sanitary and environmental impact which might result from the diffusion of these POPs in Yaoundé VII sub-division. This descriptive, transversal and retrospective study was carried out from February to May, 2013. 100 Cameroonians aged 20 years and above took part in the study. A survey comprising globally of the sources of production of POPs and the identification of sanitary and environmental impact was performed. The results obtained were analysed using the STAT 11.0 software. The association between an exposition to a toxic chemical substance and the appearance of symptoms was measured through the estimation of the impact which corresponds to the calculation of the event rate. The proportion of participants aged more than 30 years was significantly higher than the proportion of participants aged 20 to 30 years (p<0.05). The participants did not follow any training for the use of pesticides. 70% of them did not know what is known as a POP pesticide, were ignorant and bought pesticides in the black market. An absence of the individual protection equipment was observed in the market-gardeners. The number of market gardeners having skin irritation and headaches daily after application of the pesticides was significantly higher as compared to the market gardeners not presenting any symptom, with respective risk of 0.9 and 0.8 for occurrence of each symptom after exposition. The number of users having headache, blurred vision and fatigue after manipulating paints was significantly higher as compared to users presenting no symptom, with respective risk of 0.9, 0.8 and 0.8 for occurrence of each symptom after exposition. It is worth noting that 15% of the study population was involved in the non-intentional production of POPs (dioxins and furans) through incineration of garbage. The sources of intentional production of POPs were: the wood transformation factory, the industry for production of plastic plates and cups as well as clandestine pastries. In conclusion, the diffusion of POPs in Yaoundé VII sub-division could be associated with sanitary impact which varies from one individual to another. The assessment of the environmental risk was not exhaustive and therefore requires a more advanced study in which the POPs will be analysed in samples such as water, soil, air and food.
Key words: Health, environment, risk, persistent organic pollutants (POPs), Yaoundé. 


The health of individuals as well as the communities in which they live is determined by many factors. These include income, their interaction with the society, the existence of basic services such as electricity and drinking water, the quality of services available, the practice of sanitation, hygiene, individual responsibility and the quality of the environment. Indeed, the health status of the human population is intimately linked to the integrity of the ecosystem. However, our current lifestyle generates unacceptable health and environmental consequences. The United Nations Organization (UNO) and the World Health Organization (WHO) support the implementation of new skills, including the practice of a concerted fight against pollution which will help in the creation of healthy and sustainable communities (Jorgenson, 2001). That is why for over 20 years, the issue of the fight for the protection of the environment has raised considerable and renewed interest. 
At the beginning of the 21st century, many African countries prepared programs that were very optimistic in their forecasts on hygiene and sanitation but whose aims have been difficult to achieve (Franceys et al., 1995). Since then, these countries have initiated the process of decentralization, which takes the consideration of sanitation problems more seriously. In Cameroon, the fight against poverty has led to the development of several strategic plans and programs for the improvement of the quality of the life and health of the population. In Yaoundé, projects to improve hygienic conditions through the sanitation of the environment, the creation of green spaces and better management of solid waste were initiated by the Yaoundé City Council with support from the state. However, it is rather unfortunate that the matter of the fight against air, water and soil pollution, by diffuse chemicals remains of little concern. Yet, the management of chemicals in industries and suburban areas is deplorable. The rate of this phenomenon of diffuse pollution pushed Cameroon in May 2001 to sign and in May 2005 to ratify, the Stockholm Convention on Persistent Organic Pollutants (POPs), which aims at restricting and further eliminating their production, use and disposal. At the end of the 20th century, several non-governmental organizations (NGOs) activated and prepared programs that were very optimistic about the implementation of the Convention in Cameroon (Ngah et al., 2005). 
Very few studies on the diffusion of POPs and their associated impact have been conducted in the city of Yaoundé. The present study thus finds its interest in the search for measures to limit health and environmental impact due to the dissemination of POPs in the district of Yaoundé VII.
General objective
To assess the environmental and health impact associated with the dissemination of POPs in the district of Yaoundé VII.
Specific objectives 
To assess knowledge of the participants of the POPs; to evaluate the practices and behaviors of the participants in the management of POPs; to assess the environmental and health impact associated with the dissemination of POPs.


Study type

This is a descriptive, cross-sectional and retrospective study. It is known that the main objective of descriptive surveys is to measure the frequency of a health problem. This involves the choice of a representative population of sufficient size to be able to show the reality. The cross-sectional survey conducted allowed us to study at particular points, some groups of interest in the population that gave an instant overview of the epidemiological situation related to the management of POPs. This study was conducted from February to May 2013. It involved 100 Cameroonian participants of both sexes recruited randomly from the general population of the Yaoundé VII District based on: Inclusion Criteria (more than 20 years old, be a painter, farmer, mechanic, stone cracker, industrial laborer, or housewife of good character in the Yaoundé VII District) and the exclusion criteria (below 20 years of age; not carrying out one of the following professions: painter, farmer, mechanic, stone-cracker, industrial laborer or housewife in the Yaoundé VII District; not enjoying full mental capacities).


Two types of sampling approaches could be used in determining the size of the study population. These included the probabilistic or random sampling and the empirical or non-probability sampling. The technique of non-probability sampling or simple and accidental sampling was used for the following reasons: the unknown number of workers, the limited financial resources available for the study, and the working time. After identifying of activities generating potential POPs in districts with the help of municipal officials, all the participants, after having been informed about the relevance of the study and after fulfilling the inclusion criteria , were administered the study questionnaire. Thus, 100 participants were surveyed. The sample size was determined based on the financial resources allocated for the study (Perrien et al., 1994).

Ethical considerations

This study was approved by the Divisional Officer of the Yaoundé VII District according to decision No. 004/ACD/J06/07/BAG. Thus, after having been informed on the relevance of the study, participants freely answered questions, with the utmost respect of research ethics by the investigators.

Investigation procedure

In view of the great diversity of the sources of dissemination of POPs, and in order to present a true picture of the polluting activities in the Yaoundé VII District, three questionnaires were administered to the population. A first questionnaire reserved for vegetable growers comprised of the following parts: personal identification, knowledge of POPs pesticides, method of pesticide use, health and environmental risks (20 respondents). A second one was reserved for painters, mechanics and tradesmen hardware store keepers that consisted of the following parts: identification of respondents, knowledge of POPs management, painting practices, health and environmental impact (20 respondents). The third questionnaire had two parts (the first part reserved for households on the management of household waste and the second reserved for stone crackers in quarries). Once more, information was sought: identify-cation of respondents, knowledge of POPs, health and environmental risks related to unintentionally produced POPs (60 respondents). The face-to-face method was the main one used for the administration of the questionnaire because it has the advantage of allowing the investigator to clarify issues possibly misunderstood or not understood at all, to identify the respondent and also to verify the reliability or the accuracy of some responses (Amerien et al., 1996). The health impact was assessed using a questionnaire with open graded questions.

Statistical analysis

The results were encoded in the Epi Data 3.0 software and then extracted to the STATA11.0 for analysis. The Shapiro-Wilk test was used to evaluate the normality of the results. Statistical techniques based on the calculation of frequencies or percentages in function of the total number were used (Excel 2010). The association between exposure to toxic chemicals and the occurrence of symptoms was measured using impact estimation that corresponds to the calculation of the events rate. 


The objective of this study was to evaluate the environmental and health impact associated with the dissemination of persistent organic pollutants (POPs) in the environment of the Yaoundé VII District. The 100 participants included in the study were divided into three groups: 20 practicing vegetable agriculture, 20 involved in the manipulation of paint and 60 involved in activities that could result to the generation of POPs. The proportion of participants aged over 30 years was significantly higher than that of participants between 20-30 years. People aged over 30 years were more exposed to POPs in this district. The proportion of men was significantly higher than women. This can be explained by the fact that most of the targeted activities of the study are performed by men. Persons carrying out such activities included farmers, merchants, carpenters, mechanics, painters, housewives, students, etc. A huge part of this study population was involved in waste incineration shown to be one of the processes of unintentional production of POPs.

Of the 20 vegetable growers surveyed, nearly half (43%) had at least secondary education, a minority (24%) had higher education and 33% primary education. All the participants had not undergone any training on the use of pesticides and proceeded most often by reading the directions on the packages (16 users) or by routine (4 users). However, the labels on pesticides rarely indicate the risks involved in their use. They are simply known as chemical substances intended for preventing, destroying or controlling pests, weeds and disease vectors. The study showed that most of the gardeners (60%) had used the pesticides for over 12 years, knowing what they are. Unfortunately, the majority (70%) of these users did not know what a POP pesticide is, though exposed daily to these toxic substances that are capable of causing several deleterious effects on humans.

The use of POPs pesticides was banned in Cameroon by the Stockholm Convention and Chapter II, Article 4, paragraph 4 of Decree No. 2011/2582/PM of August 23rd 2011, on the modalities of the protection of the atmosphere in Cameroon declared by the Prime Minister, Head of Government. In spite of that, it was noted, that pesticides (fungicides: Hexa-chlorobenzene, Insecticides: Drinox, Altox, Xylogil (Aldrin + Lindane) the Aspon: Chlordane, the Citox: DDT and Quintox: Dieldrin) are still used by the gardeners. This is explained by the fact that 70% of them were ignorant of the ban and bought pesticides in the black market which respects no regulations.

Contrary to what is usually believed, one does not necessarily have to breathe pesticides to be significantly exposed. However, the exposure may be through dermal, respiratory and/or oral pathways (Damalas and Eleftherohorinos, 2011). The lack of personal protective equipment was observed in the vegetable cultivators. This could be the main cause of the acute symptoms experienced after pesticide application. Thus, showing the health impact linked to their use, in fact such exposure can cause acute effects such as respiratory difficulties, skin irritation, headaches, blurred vision, fatigue (Zuskin et al., 2008), etc., and chronic effects such as endocrine disruption (reproduction) (Hirakawa et al., 2000; Gore, 2002), congenital malformation (teratogennicity), induction of tumors and cancers (carcinogenesis) (Purdue et al., 2007; Bonner et al., 2005), gene mutation (mutagenesis), neuro-toxicity (central and peripheral nervous system) and immunosuppression (Lori et al., 2012). In this study, the association between pesticide exposure and the onset of symptoms showed that all the symptoms described by the gardeners and regularly observed were acute.

The number of participants who had skin irritation and headaches after pesticide application was significantly higher than those without symptoms, with event rate of 0.9 and 0.8 of the occurrence of symptoms after exposure (Table 1).The gardeners said that these symptoms disappeared after rest and recovery by the consumption of milk. However, they ignored the phenomenon of bioaccumulation of the POPs contained in the pesticides. The endocrine disruption activity of some POPs was observed after long term exposure as a result of their bioaccumulation potential (Harald  et al., 2000). This phenomenon of bioaccumulation leading to chronic toxicity can result to death. However, it was reported that no death due to pesticide intoxication was recorded in the work area.

The water point nearest to the gardens served for gardening and for rearing animals. The distance (20 m) between this water point and the garden was such that one could believe that there is no risk to the animals that drink from it. However, 35% of the gardeners declared that they throw pesticide containers in the river, which would probably pollute the water with POPs residues. Another proportion of the participants (40%) burned the containers outdoors. This could constitute another unintentional source of production of POPs (dioxins and furans). An analysis of the knowledge of 20 participants who manipulate paint in the district showed that half of them did not know what POPs are. This could be explained by the fact that after the ratification in May 2005 of the Stockholm Convention on POPs by the Cameroonian government, only some populations in some parts of the country were sensitized on the dangers of these toxic substances to humans and to the environment. This level of ignorance is preoccupying because the users are at high health risk due to the handling of paint without personal protective equipment (PPE). The contact of paint with the skin and eyes, and inhalation of its vapor could be responsible for acute symptoms experienced. As in the case of pesticide exposure, these include breathing difficulties, skin irritation, headaches, blurred vision and fatigue. The event rate of headaches, blurred vision and fatigue after handling paint was observed to be high  with  respective  values  of  0.9;  0.8  and 0.8 for the onset of these symptoms after each exposure (Table 2).

The presence of residential houses near the paint booths could constitute a health risk to third parties as a result of continuous exposure to paint residues rich in POPs due to their characteristic phenomenon of long-distance transport and persistence in the environment. The environmental risks associated with the use of paints can be resumed to air pollution because their manipula-tion is carried out in open air. This is a serious case of ignorance because in addition to polluting the production site, the pollutants travel a long distance and pollute other places. Of the 60 participants recruited during the search for other sources of production of POPs in the Yaoundé VII District, it appeared that nine of them through their waste incineration activities could have unintentionally produced POPs (dioxins and furans), while being ignorant of the risks associated with dioxin poisoning.

Other sources of unintentional production of POPs could be a wood processing plant that uses a range of chemicals products rich in POPs such as Xylogil containing Aldrin and Gamma 20 which contains lindane. These pesticides are widely used for the protection of wood against termites. Industries manufacturing plastic dishes and spoons through the combustion of plastics; industries manufacturing toilet tissues drain waste oils rich in hydrocarbons into rivers; clandestine bakeries operating without devices for smoke filtration before its release into the environment via the chimney are also various sources of the environment hazards.


A knowledge of the effects of a chemical substance leads to a  responsible  approach  towards its management and use. At the beginning of the 21st century, the threats posed by POPs on human health and the environment are a real challenge for Cameroon as well as most countries in the world. In view of the dangerous nature of these products, everyone is called upon and required to participate in the fight against them by sensitizing their environment and the community in general. It is in this light that the level of knowledge of POPs was tested and the practices and behavior on their management assessed in order to evaluate the environmental and health risks associated with their use in the Yaoundé VII District. The results showed that 70% of vegetable pesticide users did not know what a POP pesticide is; 50% of people in daily contact with paint did not know what a POP is; other sources of POPs are the waste incineration, incineration of wood and old car wheels in stone quarries, and other industrial discharges. A global ignorance regarding POPs was observed in this district accounting for no reduction therefore in the production of these dangerous substances. Persons handling pesticides without PPE were 0.9 times more likely to have a skin irritation and, 0.8 times more likely to develop headaches. Persons handling paint without PPE were 0.9 times more likely to develop headaches and 0.8 times more likely to experience blurred vision and fatigue. Therefore, the dissemination of POPs in the district could be associated with various health risks from one individual to the other.

The assessment of environmental risk was more difficult because of limited resources to perform the sampling and assay of POPs in water, soil, air and food. Nevertheless, some discharges were identified which may have an impact on the environment, such as through waste incineration. It was also shown this study that, there was a low level of awareness of the population on issues relating to persistent organic pollutants. With this in mind, an exhaustive analysis of POPs in Yaoundé can only succeed through a prior intensification of awareness of not only the people but also the private sector, including industry, for the effective involvement of all stakeholders in the fight against these dangerous products. From all that proceeds, it can be said that the population and immediate environment of this district are abusively contaminated by POPs and it is therefore of importance to undertake urgent and necessary remedial actions. Hence, it is most necessary to undertake further studies by sampling biotic and abiotic compartments to assess the degree of contamination and then take appropriate action.


The authors did not declare any conflict of interest.


The authors thank the teachers of EITMS-GS YDE, the members of M3 Laboratory of the BTC UYI, the Head of the Health-Environment Department of the Yaoundé VII District, and all study participants.


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