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Table 1 Operational definitions used in the study

From: Novel risk factors for primary prevention of oesophageal carcinoma: a case-control study from Sri Lanka

Term Definition used in the study
‘High risk’ drinker A person who has consumed more than three standard drinks on any day or more than seven standard drinks per week for women, and more than four drinks on any day or more than 14 per week for men [62].
Standard drink: Quantity of any type of drink, containing 10 grams of pure alcohol [62, 63].
The volume of alcoholic beverage consumed per session was based on standard volume measures for different types of alcoholic beverages consumed (e.g. glass, shots, bottles) and the total volume of ethanol consumed per session per week was calculated using the standard ethanol amount in the drinks [64].
‘Sub-optimal’ consumption of fibre and antioxidants Inadequate consumption of food containing dietary fibre and anti-oxidants [37].
‘Sub optimal’ consumption of deep fried food Overconsumption of deep fried food [37].
Consumption of beverages at extreme temperatures Daily consumption of hot beverages (tea/coffee) within at least 2 minutes of preparation
Consumption of excessive chilli Daily consumption of meals prepared with excessive additional chilli
Food/beverages with excessive colour Any coloured food/beverage that would stain the fingers, lips and tongue upon its consumption
‘Low’ and ‘high’ total lifetime physical activity levels Lifetime total physical activity (average MET-hours per week per year) in relation to occupation, household and sports and exercise activities [37, 65].
‘Low’ level of physical activity = the score that corresponded with the 25th percentile and ‘high’ level of the physical activity = the score that corresponded with the 75th percentile of the distribution of total scores of all participants
Ever smoker A person who had smoked 100 or more cigarettes/sticks of bidi in his/her lifetime [66].
Exposure to passive smoking A person who has/had been exposed to second hand smoking in confined areas (at home or work) for at least once a week for three consecutive months during the past one year
Ever betel chewer A person who has/had the habit of betel quid chewing (with or without additives) at least three times per week, continuously for six months or more in the lifetime
Exposure to agrochemicals Direct and/or indirect exposure to agrochemicals
Where;
‘Direct exposure’ to agrochemicals = Persons who have been farmers/cultivators for at least six months during which they have been involved in spraying/handling agrochemicals
And
‘Indirect exposure’ to agrochemicals = Persons who have been living at least for six months in close proximity (within 100m) and/or working in close proximity (10m) to an environment consistently exposed to agrochemicals
Exposure to home/industry based chemicals Direct and/or indirect exposure to home/industry based chemicals
Where;
Direct exposure = persons who have been working at least six months during which they were directly exposed to home/industry based chemicals for at least three days per week
And
Indirect exposure = Workers who have not been directly handling chemicals, but have been working for at least six months in close proximity (10m radius) to an environment consistently using home/industry based chemicals
Major source of drinking water The source of drinking water from which he/she consumed water consistently at least once a day, during the last one year.
If there were more than one source (eg: pipe borne water consumption at the work place and consumption of well water at home), most frequently used source of drinking water was considered
Exposure to indoor air pollution Use of fire wood as the main source of fuel in the household and having the kitchen built attached to the house
Exposure to outdoor air pollution Person who has been living at least for six months in a place adjacent (within 20m) to a main road and/or living at least for six months in close proximity (within 100m radius) to a factory with smoke emission
Prolonged medication for co-morbid conditions A person who had been on a drug regime (oral medications) for at least six consecutive months, during the last 10 years
Vitamin supplementation A person who had been on vitamin supplementation for at least one month consecutively during the last 10 years
Exposure to ionizing radiation A person who has been exposed to any type of ionizing radiation (eg: X-ray, CT, Gamma rays) within the past 10 years irrespective of the indication