Chemical Pollution of Drinking Water in Haiti: An Important Threat to Public Health

*Alexandra Emmanuel and Evens Emmanuel*

### **Abstract**

The geophysical environment of the Republic of Haiti is characterized by hydrological and biogeographical climatic phenomena, and a relief marked by its rugged appearance. Most of the territory is occupied by mountains formed of limestone. The differences in level are very marked. Fragmentation is another feature of the relief. These environmental imperfections juxtaposed with difficult socioeconomic conditions and anthropogenic actions raise questions about possible chemical metal pollution of the country's water resources. Indeed, the predominance of limestone in the Haitian geology generate water hardness, and in the case where the magnesium concentration is less than 7 mg/l, this water may be the source of cardiovascular diseases. Studies carried out on several water points show a total hardness greater than 200 mg/l. In Port-au-Prince, concentrations of lead ranging from 40 μg/L to 90 μg/L and high Cr (III) risks were measured and estimated in groundwater and drinking water. Concentration of fluorine ranging from 0 to 2 mg/l were obtained from water resources. Concentration above 1.5 mg/l have been found from alluvial aquifers. Chronic public health risks, such as cardiovascular diseases, deterioration of the psychological development of children, irreversible functional and morphological renal changes, and dental fluorosis, strain Haiti's water resources. Chemicals' exposures seem to pose a threat to public health in Haiti, which need to be studied. The aim of this study is: (i) to analyze the contribution of geology and anthropogenic actions in the alteration of water quality, (ii) to review the toxicology of chemicals detected in water distributed in Port-au-Prince.

**Keywords:** chemical pollutions, drinking water, environmental health, medical geology, One Health, Haiti

#### **1. Introduction**

Water is essential for sustaining life, yet it is also the source of many diseases for living things [1]. With the increase in population and the development of industrial activities, surface water resources and groundwater have become increasingly polluted. Thus, humans are exposed to many chemicals found in drinking water.

Several chemicals (organic and inorganic) have been identified in drinking water, and the sources of pollution of the drinking water system are multiple [2]. Among these pollutants, the literature reports particularly chlorine disinfection byproducts [3–5], fluorine [6–8], lead [9, 10] chromium [11–13], cadmium [14, 15], nitrates [16, 17], pesticides [18, 19], hardness [20, 21], arsenic [22, 23], etc. The presence of chemical substances in the municipal drinking water is a major health concern. Indeed, some substances detected in drinking water have been the subject of epidemiological studies [1]. The health effects reported in the literature are different cases of cancer, reproductive problems (malformations) cardiovascular and neurological diseases. Drinking water is therefore an important route of exposure to chemicals.

Pollutants, particularly heavy metals are released into the environment from a wide spectrum of natural and anthropogenic sources [24]. Heavy metals are omnipresent in the environment, occurring in varying concentrations in air, bedrock, soil, water, and all biological matter [25, 26]. The principal anthropogenic sources are industrial and urban effluents, runoff water, drinking water production and distribution equipment and drinking water treatment processes [1]. The presence of heavy metals in the environment constitutes a potential source of both soil and groundwater pollution.

In Haiti, the work carried out in the field of the physicochemical quality of water intended for pollutants such as: lead, chromium [27], fluorine [28]. Excessive concentrations of hardness have also been observed in water resources [29]. These concentrations of natural origin are added to those generated by anthropogenic actions, such as poor management of solid waste, the absence of urban sanitation networks and water treatment plants only increase the rate of human exposures to these pollutants. These exposures to chemical substances continue to put Haitians at risk, and several examples shed light on the realities of risk management with respect to toxic chemicals in developing Countries [30]. The fact that the hydrographic basin of Port-au-Prince consists mainly of karst aquifers [31], rainwater, polluted by atmospheric particles of substances originating from industrial activities, and urban wastewater feeds, through the dominant geology, groundwater, thus leading to suppose that the water resources of this region are subject to significant chemical pollution.

The impact on human health of natural materials such as water, rocks and minerals has been known for thousands of years, but there have been few systematic and multidisciplinary studies on the relationship between geologic materials and processes and human health (the field of study commonly referred to as medical geology) [32]. In order to achieve a better understanding in urban and rural areas of Haiti of the different routes of exposure and the causes of a number of environmental health problems generated by exposure to high concentrations of essential and nonessential chemicals for the organism that are detected in drinking water, it seems relevant that geoscientists, environmental and health science researchers; as well as public health specialists combine their skills to approach the problem of pollution of water intended for human consumption by taking into account the two main sources of the qualitative degradation of water: "geological contributions and anthropogenic actions". The aim of this study is: (i) to analyze the contribution of geology and anthropogenic actions in the alteration of water quality, (ii) to review the toxicology of chemicals detected in water distributed in Port-au-Prince.

## **2. Medical geology and environmental health in the geographical context of Port-au-Prince**

#### **2.1 Environmental health and assessment of health risks associated with chemical mixtures in drinking water**

During the 1950s, forms of anxiety gradually manifested themselves regarding the state of environmental degradation and its harmful consequences for the

#### *Chemical Pollution of Drinking Water in Haiti: An Important Threat to Public Health DOI: http://dx.doi.org/10.5772/intechopen.97766*

survival of ecosystems and for development [33]. Indeed, since the said decade, the environment-human health relationship has become a major concern in the field of public health. The questions of contaminated soil, emanations from landfills, destruction of the ozone layer, global warming, food contamination, radiation emitted by household appliances, new biological hazards … are among the subjects of intervention by government authorities [34].

Abenhaim [35] argues "Environmental health issues are among the most complex for scientists to study and the most difficult for policy makers to resolve. First, because it is rare that the exhibitions are pure, thus leaving room for many confounding factors. Then, because the contaminations are generally in relatively small quantity, at the limits of the observable effects. Finally, because the consequences of exposure often occur over the long term" [35]. Exposure to chemical mixtures is a reality that would seem to dictate the need to pay much attention to hazard identification, exposure assessment and risk characterization [36], of mixtures in water intended for human consumption. Contrary to this environmental reality, the toxicological reality is that until recently most of the research carried out in this field has been devoted to studies on the effects of substances acting independently, without considering the interactions or combined effects between pollutants at the inside the human organism [37].

In Haiti, all the work carried out on the health risk linked to the pollution of drinking water by chemical substances, the risk characterization was made based on the independent effects of the pollutants studied. This approach provides information on the level of exposure of the population to a substance but does not make it possible to assess the interactions of the various pollutants detected in the distributed water. It is now widely recognized that studying the combined effects of chemical mixtures in drinking water is an integral part of public health [37]. Characterizing the combined actions of chemical mixtures involves the challenge of how to define the antagonistic, additive, or synergistic effect. It is therefore important to understand the terminology that describes the combined effect of the agents in terms of the mechanism of action. Seventy years ago, three basic concepts of common action or the interaction of the combination of chemicals were defined by biomathematicians [38–40] and they are still valid today.

Indeed, Bliss [38] identified three modes of action of constituents within a mixture vis-à-vis living organisms:


All three basic principles of common action of pollutants are theoretical. However, these concepts will most likely need to be addressed at the same time, especially when the mixtures consist of more than two compounds and when the targets (individuals rather than cells) are more complex.

Fox et al. [41] considers the risk assessment of chemical mixtures or the cumulative risk assessment (CRA) as the most recent step in the evolution of assessment. USEPA [42, 43] defines this approach as an analysis, characterization, and possible quantification of the combined risks to human health or the environment due to multiple substances or stressors. This definition suggests that additivity is the initially accepted mode of action for the implementation of ERC.

U.S. EPA [44] developed for the implementation of cumulative risk assessment, the Hazard Index (HI) method. This approach first assesses the effects of a substance acting independently of the others. HI is calculated by dividing the measured or estimated exposure concentration by the reference concentration (RfC):

HI ¼ Measured or estimated exposure concentration*=*RfC

For HI < 1, the exposure concentration is below the cutoff value, so no health effect can be expected. On the other hand, for HI ≥ 1, the exposure concentration exceeds the threshold value, further research on the health effects of the pollutant is recommended, by calculating the Hazard metric HM.

HM ¼ Measured or estimated exposure concentration*=*NOAEL or adjusted LOAEL

Based on the additive action of pollutants, the application of the HI or HM model to assess the concentration of exposure due to chemical mixtures can be also expressed:

$$LCE = \frac{C\_1}{M\_1} + \frac{C\_2}{M\_2} + \frac{C\_n}{M\_n} \le 1\tag{1}$$

LCE: Limit of exposure concentration

C1, C2 and Cn: observed concentrations.

M: Maximum acceptable concentration (threshold value)

In the distribution units where chlorination is applied to raw water rich in organic matter, a quite common situation or process in Haiti, the populations served are exposed to a certain number of chemical substances (by example Disinfection by-products (DBPs)), very known for their adverse effects on human health, especially the occurrence of cancers [45, 46]. In the absence of national standards for the quality of drinking water, Haiti applies the guidelines of the World Health Organization. The application of the HI or HM model in the evaluation of the combined effects of by-products could be, in a simplified manner, carried out from:

$$\text{CHMs} = \frac{\text{EcCHBr}\_3}{\text{TS}\_{\text{WHO}}\text{CHBr}\_3} + \frac{\text{EcCHBr}\_2\text{Cl}}{\text{TS}\_{\text{WHO}}\text{CHBr}\_2\text{Cl}} + \frac{\text{EcCHBrCl}\_2}{\text{TS}\_{\text{WHO}}\text{CHBrCl}\_2} + \frac{\text{EcCHCl}\_3}{\text{TS}\_{\text{WHO}}\text{CHCl}\_3} < 1 \tag{2}$$

THMs: Trihalomethanes EC: Exposure concentration CHBr3: Bromoform CHBr2Cl: Chlodibromomethane CHBrCl2: Bromodichlomethane CHCl3: Chloroform

TSWHO: WHO threshold value Different types of complex mixtures require different approaches, and the usefulness of a certain approach depends on the context in which one is confronted with a mixture, and on the amount, type and quality of the available data on the chemistry and the toxicity of the mixture [47]. Scientific literature reports the occurrence of several detected in drinking water in Haiti [26–29]. Moreover, MSPP and WHO [48] note "the quality of water intended for human consumption is not subject to any control. In such a context, the study of *Chemical Pollution of Drinking Water in Haiti: An Important Threat to Public Health DOI: http://dx.doi.org/10.5772/intechopen.97766*

the combined effects of several chemical substances in drinking water and the assessment of the risks generated for human health constitute an important topic of transdisciplinary public health research.
