|Year : 2014 | Volume
| Issue : 2 | Page : 105-106
Fish smoking and COPD: A fishy affair
Sundeep Salvi, Bill Brashier
Chest Research Foundation, Pune, Maharashtra, India
|Date of Web Publication||1-Apr-2014|
Chest Research Foundation, Pune, Maharashtra
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Salvi S, Brashier B. Fish smoking and COPD: A fishy affair. Lung India 2014;31:105-6
An estimated 115 million tons of fish are harvested as human food from the seas, oceans, lakes, and rivers every year globally;  making it the largest extractive use of wildlife by humans on this planet. About 94% of all freshwater fisheries occur in developing countries  where they provide food and a livelihood for millions of people and also contribute to the overall economic well-being by means of export commodity trade, tourism, and recreation. Because fish cannot be preserved for a long time, unless they are refrigerated, humans have developed innovative methods of fish processing to increase their shelf-life. Wind drying was the most ancient and basic way of preserving fish. After the discovery of fire, early humans found that fish hung up over a fire dried more quickly, and that, if the fire was smoky, fish would acquire a different flavor and keep better. Fish smoking has subsequently become a very popular method for preserving fish and is now practiced in all regions of the world.  In India, fish smoking is widely practiced in Orissa, West Bengal, Assam, Arunachal Pradesh, Manipur, Madhya Pradesh, some pockets on the west coast, and the Godavari and Krishna deltas in Andhra Pradesh.
Fish smoking combines the effects of drying, heating, and smoking; coupled sometimes with salting. The pretreatment involves gutting, splitting, kench salting, brining, and/or drying depending on the smoking method. A combined heating/drying/smoking process entails application of smoke using suitable firewood, passing it over fish in a closed chamber at temperatures of about 30-35°C for a cold smoked product or 70-80°C for a hot smoked product. Fish smoking is traditionally performed in a thatched hut, in which a raised platform with bamboo mats are spread across, called Jithaga. The fish for smoking are placed on these mats for a period of 18-24 h. In the pits beneath the platform, firewood, generally mangrove wood or any other combustible material available in the village is placed and burnt. Smoke then envelopes the hut, and temperature rises up to 50°C. The smoked fish are then packed and sent to the market for selling.[Figure 1]
|Figure 1: Fish smoking is an important occupation associated with chronic obstructive pulmonary disease (COPD)|
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Smoke from the burning of biomass fuels has been shown to be a major risk factor for several respiratory ailments, such as asthma, chronic obstructive pulmonary disease (COPD), respiratory tract infections especially in children and the elderly, and lung cancer.  An estimated 50% of the world's population (i.e. around 3 billion people) use biomass fuel for cooking and heating purposes. Burning of biomass fuel produces more than 200 different chemical compounds, over 90% of which are in the inhalable size range. These include gaseous air pollutants such as carbon monoxide, sulfur dioxide, nitrogen dioxide, and particulate matter air pollutants such as those less than 2.5 microns (PM2.5) and those less than 10 microns (PM10) in aerodynamic diameter, polyaromatic hydrocarbons, chlorinated dioxins, arsenic, lead, fluorine, and vanadium; all of which are toxic to the human body. 
In this issue of the Journal, Umoh and colleagues  report the adverse effects of exposure to biomass smoke in the smoking fish industry on lung function decrements and increase in respiratory symptoms observed in the rural fishing community of Obaka in Nigeria. Compared to women who did not work in the smoking fish industry, women who worked in the smoking fish industry had an almost 1.5-fold decrement in peak expiratory flow rates (PEFRs), forced expiratory volume in 1 second (FEV 1 ), and forced vital capacity (FVC) values. Moreover, the prevalence of symptoms of chronic bronchitis was 68% among women who worked in the smoking fish industry, compared to 8% among those who did not work in the smoking fish industry. The mean FEV 1 /FVC ratio in these women was 68%, indicating that a sufficiently large proportion of women in the smoking fish industry had significant airways obstruction. Interestingly, both the women groups used biomass fuel for cooking, indicating that additional exposure to biomass smoke in the fish smoking industry has a further worsening effect on lung health. This is likely because exposure to biomass smoke during cooking lasts for 2-4 h every day, while exposures to biomass smoke at fish smoking industries will be continuous for 24 h.
This is perhaps one of the first studies that have identified fish smoking as an important occupation associated with the risk of developing COPD in developing countries where biomass fuels are widely used in this occupation. There are several other factors that may have contributed or further confounded the observations made in this study, such as poor socioeconomic status, poor nutrition, exposure to other sources of indoor air pollutants such as mosquito coils and kerosene lamps. But nonetheless, this study highlights the fact that fish smoking is an important industry that is associated with a risk of developing obstructive airways disease, likely to be COPD.
Although people working in the smoking fish industry have a significantly increased risk of worsening of lung health and the risk of developing COPD, it is important to realize that smoking fish may be the only source of livelihood for these people living in the coastal region or along river beds, and it may therefore be difficult to give up this occupation for economic reasons. Smoking fish industry is a small industry and does not come under the jurisdiction of regional occupational norms or even get notified. Fuelled with poor access to healthcare facilities, health hazards related to indoor air pollution are likely to remain unnoticed in this population until later stages.
This problem remains to be tackled on various fronts. Firstly, more population-based epidemiological studies are required to investigate the true burden of COPD in the fish smoking industry. It may be possible that these people may also have an increased risk of pulmonary tuberculosis, interstitial lung disease, and lung infections. Secondly, the government and health authorities need to establish some disease notification systems for chronic respiratory diseases among people working in these occupations. This is important because COPD is emerging as primary killer disease in most developing countries, and identification of this disease during the early stages may help prevent the further lung damage. Thirdly, we need to educate the people working in this trade as well as public health officials and medical care providers about the harmful effects of exposure to the smoke at this workplace. And finally, to preserve the age-old tradition of smoking fish and retain the flavors that they are popular for, innovative interventions need to be developed to ensure that the exposure levels to people are reduced to as low level as possible. [Table 1] lists the various occupations associated with the risk of developing COPD. Fish smoking will now need to be added as another occupation associated with the risk of COPD.
|Table 1: Occupations associated with the risk of developing chronic obstructive pulmonary disease|
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| References|| |
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|4.||Kodgule R, Salvi S. Exposure to biomass smoke as a cause for airway disease in women and children. Curr Opin Allergy Clin Immunol 2012;12:82-90. |
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