Seawater was poured on pan like plastic batches and sun-dried for 48 hours. Figure 2 depicts the technic.

· A 3.00 m × 1.00 m crystallizer was made, the bottom of which is lined with black tarpaulin of rectangular section with a depth of 0.10 m; the equilibrium of which is maintained with wood.

· Seawater is poured in the crystallizer and allowed to evaporate under the action of the sun and wind, living behind crystallized salt.

A total of 48 crystallizers are set up within an area of 40 m × 30 m fenced with local materials made from branches of oil palm trees.

Daily work, consisting of collecting seawater from the seashore to the salt plant, starts at 6 a.m. and ends by 9 a.m. By 4 p.m., a small amount of salt crystal is formed in the crystallizer.

The favorable period for this activity extends from November to May corresponding to the dry season. On average, 150 kg of salt is produced monthly for a total of 900 kg annually. The nutritive quality of the salt is determined by its iodine content. The chemical analyzes carried out by the Food and Applied Nutrition Department (DANA) revealed that this salt is poor in iodine. Iodization of the harvested salt is one of the challenges faced by this group of women. Another challenge is the transportation of seawater from the seashore to the plant. Women have to carry on their head 50 L-containers filled with seawater for over 3 km on a sandy path. Installation of a pumping system as a solution is envisaged, but the technology is not well mastered because of the violent waves of the sea.

Seawater is a natural source of salt. It has salt at an average of 35 parts per thousand. The earliest method of salt production was the evaporation of seawater by the heat of the sun. This method was particularly suited to hot, arid regions near the ocean or near salty lakes and is still used in those areas. Seawater evaporation technology has been employed over time and generations [21]. The process for extracting salt from seawater is an ancient technology and involves evaporation within shallow ponds. One aspect of this technology is that shallow, water-proof ponds are dug out and connected to the sea by means of canals. A broad area and shallow depth allow a given volume of water to absorb more sunlight [22]. The pond is flooded, and then the canal is closed. The sun evaporates the water. As the water vaporizes, the salt remains behind, creating ever more saline water. Eventually enough of the water evaporates to leave behind a layer of sea salt crystals that can be harvested. Modern sea salt extraction operations typically have a number of these ponds concentrated in one location, separated by levees [21] [22] [23]. Unlike the technology employed at Sèmè Okoun, there is no canal connecting the sea to the ponds, and women have to collect seawater and transport it on their heads to fill up the ponds. Actually, one common challenge to seawater evaporation to harvest salt is rain. An untimely rain can ruin days of evaporation [21]. This is the reason for which at Sèmè Okoun, and elsewhere, salt harvesting from seawater evaporation is limited to the dry season period, or mostly developed in the dry areas. The vacuum pan evaporation is also used to produce salt [24].

For the other five municipalities, table salt production occurs in marshy areas subject to frequent flooding. For this reason, the salt production runs from January to May, corresponding to the dry season on the coast. The production process consists of scraping and collecting salted sand from the ground (Figure 3, Photo 2a) pouring this sand into baskets woven and watering it to drain the salt out, filtering by leachate and recovering salt water (Figure 3) Photo (2b), evaporating the salty water by cooking with wood fire and the crystallization of salt and its collection (Figure 3, Photo 2c).

The activity is carried out exclusively during the dry season, from January to May of each year due to the flooding nature of the activity areas. The production of salt on swampy sites starts from 6 a.m. and ends by 8 p.m. everyday. The daily production of salt is approximately 25 kg.

Women salt producers not only face several health issues such as headaches, muscle and lumbar pain, fevers, cough, etc., but also the hardship of the activity (clearing of marshy sites, scraping and collecting salt sand, filtering), prohibitive prices for bundles of fire wood and low prices of the produced salt.

Brine evaporation by heating to harvest salt has been practiced as traditional way and employing firewood as energy source. Brine from salt wells is boiled to produce salt at Bo Kluea, Nan Province, Thailand, as it is done in Pakistan [25]. This is a very rudimentary technic at familial level of production along with its environmental and health related issues. However, the salt production technic in south Benin Republic consisting of scratching salty soil, leaching the collected salty sand for brine, seems to be unique in the world. Literature reported on seawater evaporation [26], salt extraction from the vast sedimentary deposits, digging salt from ground. However, the technique of scratching thermosiphon salty soil is not reported in the literature, to the best of our knowledge. Women salt producers clearly pointed at the use of firewood to heat brine for salt harvesting being the principal cause of sickness resulting in respiratory discomfort, troubles in sight, coughing, headache, and pulmonary disease.

The women at Sèmè Okoun use direct sun drying technology for table salt production. This requires specific training and initial high investment costs. In 2012, the group, made of about 20 women, benefited three-week training sessions from a European NGO that helped them acquire the technique of salt production on tarpaulins. The financial needs to purchase the tarpaulins, working materials, wood frame, and to settle the plant, were satisfied partially by individual contributions and support from the Mayor of Sèmè-Kpodji through the Funds for the Development of Municipalities, the FADEC.

The distance from the seawater collection at the seashore to the salt production site, about three kilometers, represents a major difficulty. To fully develop this activity, the group of women needs to secure land along the seashore. This requires heavy investment. With the current technology deployed at Sèmè Okoun, salt production is not a year-round business. It lasts just four months after which women become jobless. This precarity deteriorates their financial situation.

The table salt production within the other groups is very rudimentary. The women use firewood to evaporate saltwater to crystalize salt. The challenges that women face are several folds: precarity of the utensils, health issues, distance to carry sand. The sand scraping hoe cuff is so short that women have to be bent for hours. This causes them to experience musculature pains. Making a wood fire to evaporate saltwater exposes them to the combustion generated particles, resulting in headaches, fever, coughing, even some pulmonary complications. Women, most of the time, have to travel long distance, four to five kilometers carrying a heavy load of salty sand on their heads. This resulted in muscle and lumbar pain. Additionally, the prohibitive prices for bundles of wood and the low prices of salt do not help the economic situation of salt producers. Moreover, the utensils are frequently damaged by corrosion (Figure 4(a)) and cannot survive a producing season.

Overall, traditional salt production can face sanitary issues, from scraping the salty soil, to filtering the salt water, distilling it, and storing the obtained salt. A total lake of hygiene was observed within the five municipalities where the traditional salt harvesting method is in use. Figure 4(b) depicts a bundle of crystalized salt, stored in poor hygienic conditions.

The table salt production technic that massively contributes to the mangrove destruction in the coastal zone of Benin Republic is the one using fire wood as source of energy to evaporate the brine. From Table 1, 82.20% of table salt producers employ wood from the cutting down of mangrove for several purposes. The leaching baskets used to obtain the brine are made out of mangrove (Figure 3(a) for empty baskets, and Figure 3(b) for loaded basket). Figure 5 depicts the type of mangrove used to make leaching baskets Figure 5(a), the basket Figure 5(b). Mangrove wood is also used to construct the shelters (Figure 5(c), Figure 5(d)) and to evaporate brine (Figure 5(e)). A substantial reduction in mangrove

surface area was attributed to table salt production on the coastal zone of Benin Republic. Paradis and Adjanohoun reported on the impacts of salt production on the vegetative mangrove in Low-Dahomey [27]. In 2006, Bamisso M. reported a degradation rate of the Benin Republic coastal mangrove of 2.4 ha per year induced in part by the dynamics of water courses and bodies, the erosion of the banks as well as various forms of exploitation such as salt farming, fuelwood, market gardening carried out by the local populations [28].

According to Orekan et al., the reduction of the mangrove surface area from 6930 ha in 2005 to 5871 ha in 2015, representing respectively 16.31% o and 13.82% of the Beninese littoral surface area is due to, among others, table salt traditional production [13].

Various causes lead to substantial mangrove reduction. In a study recently conducted by Gordon et al., a 2.8% reduction in mangrove surface area over 50 years is predicted [29], due to human settlement, and infrastructure. Aquaculture, basically shrimp production will take-up this reduction to an additional annual 0.75% of the mangrove surface area, resulting in a 54% net reduction over 100 years, after regrowth of abandoned aquaculture areas [29].

However, mangroves hold important functions in the ecosystem that is very beneficial both to human and the environment. Mangroves are home to significant biodiversity [30] [31] and play the essential role of nursery for many fish species [32] [33]. Mangrove can limit erosion and have a purification effect by filtering macro-waste [34]. They contribute to the water and nutrient cycle [35] [36]. In urban areas, they act as a sponge by absorbing excess water that could cause flooding [37]. Mangroves also act as coastal barriers or defenses against storms [19] [38] and sea level rise under certain conditions [39]. Mangroves typically provide some protection from extreme coastal events, such as tsunamis and cyclones. It was estimated an 8% reduction in the severity of impacts of the 2004 tsunami in coastal areas with mangroves [19]. Mangroves capacity to sequester carbon is key contributor to greenhouse gases reduction, the combat against climate change [29] [40].

The health issues faced by the women salt producers are dependent on the type of technology deployed. As previously highlighted, two major technics are at use for table salt production in southern Benin Republic.

For the one that uses solar radiation and wind to evaporate seawater on tarpaulins, the health complaints by almost 100% of association members are basically related to muscular and joint pains, headache, and fatigue. This is understandable since women salt producers have no mechanical means for bringing seawater from the sea to the salt production site distant of about 3 km. Those ladies have to carry heavy load of seawater on their heads, and walk on the seashore sand to the production site.

As far as the evaporation of brine by using fire wood technic, in addition to muscular and joint pains reported by 100% of the workers, some of them experience other sicknesses such as respiratory discomfort, troubles in sight, coughing, headache, and pulmonary disease.