Tag: non infectious diseases

The International Agency for Research on Cancer (IARC) part of the World Health Organisation announced that it had reclassified diesel exhaust as a 'definite carcinogen in highest category (Category 1). When diesel burns inside an engine it releases two potentially cancer-causing things: microscopic soot particles, and chemicals called polycyclic aromatic hydrocarbons or PAHs. There are three possible ways these can cause cancer. The microscopic particles making up diesel exhaust particulate matter are less than one-fifth the thickness of a human hair. They are small enough to penetrate deep into the lungs, causing respiratory disease. Inhaled PAHs could directly damage the DNA in the cells of our lungs leading to cancer. Secondly, the soot particles can get lodged deep inside the lungs, causing long-term inflammation, and thirdly this can increase the rate at which cells divide. So if any nearby lung cells pick up random mutations, this inflammation could make them more likely to grow and spread. 

So, the correct  is 'a-iv, b-i, c-ii, d-iii'.

Ulceration of the gastrointestinal mucosa is caused by disruption of the mucus layer on the gastric epithelial cells. It is wrong to believe that eating acidic foods may lead to development of peptic ulcers. Ulcer may be viewed as an extension of the cell damage found in acute gastritis. The most common sites for ulcers are the stomach and the first few centimetres of the duodenum. The main factors behind ulcer are:
(1) Reduced blood supply (Reduced blood flow and ischaemia may be caused by excessive cigarette smoking and stress, either physical or mental).
(2) Reduce mucus secretion (The composition and the amount of mucus may be altered, e.g., by regular and prolonged use of aspirin and other anti-inflammatory drugs by the reflux of bile acids and salts in chronic gastritis) and
(3) Raised levels of steroid hormones, e.g., in response to stress or when they are used as drugs in chronic gastritis by irradiation and the use of cytotoxic drugs).

Aflatoxins are naturally occurring mycotoxins that are produced by Aspergillus flavus and Aspergillus parasiticus, species of fungi. Aflatoxins are toxic and among the most carcinogenic substances known. After entering the body, aflatoxins may be metabolized by the liver or hydroxylated to become the less harmful aflatoxin M1. Grains such as corn, wheat, and rice, as well as nuts and legumes, are often contaminated with molds, often as a result of poor growing conditions, substandard or extended storage. Molds called aflatoxins can easily grow and produce a very potent carcinogen.