CT scans associated with increased risk of blood cancers (GS Paper 3, Science and Technology)
Context:
- The benefits of computed tomography (CT) imaging in clinically needed cases are well known. However, its potential for increased cancer risks and relatively high cumulative doses from multiple scans have raised concerns among the medical and scientific community.
- Sensitive sections such as children, adolescents and young adults are vulnerable and technologists must use appropriate protocols for them while they undergo CT scans.
Impact of radiation:
- Radiation doses at moderate (over 100mGy) to high (over 1Gy) values are known to cause haematological malignancies (blood cancers) in both children and adults and other cancers.
- However, there has been uncertainty about risk at low doses(less than 100mGy) that are typically associated with diagnostic CT examinations.
- A recent study suggests that even low doses of radiation have a small probability of causing blood cancer.
Basis of research:
- Researchers from the International Agency for Research on Cancer (IARC) and its partners followed up a multinational cohort of 9,48,174 individuals who underwent CT examinations before age 22 years in 276 hospitals from nine European countries.
- The final study covered about 1.3 million CT scans in nearly 9,00,000 patients. They estimated the radiation doses to the active bone marrow of each subject based on the body part scanned, patient characteristics, time period and inferred CT technical parameters.
- Fifty-one percent of the cases were younger than 20 years at diagnosis, whereas 88.5% were younger than 30 years.
- Researchers followed up the group for at least two years following their first CT scan.
Key observations:
- They identified 790 haematological malignancies including 578 cases of lymphoid malignancies and 203 cases of myeloid malignancies and acute leukaemia (AL). The mean follow-up period was 7.8 years.
- The researchers found a clear association between cumulative dose and risk of all haematological malignancies, with an excess relative risk of 1.96 per 100mGy. Gray (Gy) is a unit of absorbed dose of radiation.
- The energy absorbed in one Gy of radiation is one Joule per kg of tissue. Since Gy is a large unit, milli (one-thousandth) or micro (one-millionth) of a Gy are commonly used.
- Researchers estimated that for every 10,000 children examined today (mean dose 8mGy), one-two persons are expected to develop a haematological malignancy attributable to radiation exposure in the subsequent 12 years.
Way Forward:
- The results showed a clear dose-response between cumulative ABM dose and risk of haematological malignancies, both lymphoid and myeloid, with increased risk at doses as low as 10-15mGy.
- Patients must realise that denying to undergo CT scans needed to diagnose disease is also harmful. The study highlights the need for diligently following the basic principles of radiation protection.
Is the world closer to phasing out fossil fuel?
(GS Paper 3, Environment)
Why in news?
- The 28th edition of the Conference of Parties (COP) concluded in Dubai recently with 198 signatory countries agreeing that the world must “transition” away from fossil fuels in a “just, orderly and equitable manner” to achieve net zero by 2050.
Does the wording of the agreement suggest that the end of fossil fuels is near?
- The Dubai Consensus is significant only because this is the first time since 1995, when the first ever COP was held in Berlin, that there is a formal acknowledgement that emissions from fossil fuels are the main culprit driving global warming. So far, all agreements have only spoken of the need to stem “greenhouse gas emissions.”
- This is despite it being common knowledge that three-fourth of such emissions and 90% of carbon dioxide are the result of burning coal, oil and gas.
- It was only in the 26th edition of the COP, in Glasgow in 2021 that countries agreed to tackle coal by agreeing to “phase down” its use. It’s important to keep in mind here that “phase down” and “phase out” have no meaning on their own because they do not refer to any specific year by which the use of these fuels must terminate.
- Large, developing countries like India and China, have protested against the singling out of coal among fossil fuels, on the grounds that they need them for lifting their masses out of poverty and providing energy security.
- India, while rich in coal reserves, is still an importer of the product and has limited oil and gas reserves. China is rich in both coal and gas.
- The United States, that derives about a fifth of its energy from coal, has usually been supportive of calls to phase out coal but being heavily dependent on oil and gas reserves, has never voiced any call to action to eliminate the latter two.
- However, now that all fossil fuels have been included in the Dubai Consensus, it brings parity among fuels and acknowledgement that they all need to be done away with for the world to have a chance at preventing global, average temperatures from rising 1.5 degree Celsius over pre-industrial levels.
- But because there are no timelines yet, fossil fuels are going to be the mainstay of economies everywhere in the years to come.
Can fossil fuels be immediately replaced?
- Nearly two centuries of industrialisation has meant that there is a well-oiled infrastructure system to extract, process and distribute coal, oil and gas to all kinds of power plants and convert them to electricity and combustible products, ranging from petrol and diesel to plastic.
- Then there is the infrastructure, transmission grids and pipelines to channel these stores of energy to houses and vehicles.
- Unfortunately, power from natural sources of power such as solar and wind are not as easily available, on demand, as fossil fuel: the sun because of its unavailability at night and wind due to the temperamental nature of the ocean and atmosphere.
- The infrastructure to store all of the energy produced this way is grossly inadequate. India’s National Electricity Plan, 2022-27, plans to add nearly 87,000 MW in this period in the form of fresh coal-fired capacity: 27,000 MW via under-construction power plants and 60,000 MW from new plants.
- Oil production in the U.S. hit record levels in 2023. Since 2010, the number of oil barrels per day has tripled and gas production has risen two and half times in the country.
Transition fuels:
- The Dubai Consensus agreement stating that a transition from fossil fuel, while necessary, suggests that “transition fuels” could play a role in “facilitating the energy transition while ensuring energy security.”
- Though there is no definition of what these fuels are, natural gas has been touted as one of the contenders.
- Even though natural gas production leads to methane emissions, estimates by the International Energy Agency proffer that in balance, switching from coal-to-gas reduces emissions by 50% when producing electricity and by 33% when providing heat.
- This of course invites criticism that such a framing of natural gas advantages countries which have natural production and distribution capabilities for this gas.
What does the Dubai Consensus say about methane?
- Methane is a potent greenhouse gas and has several times more heat-trapping capabilities compared to carbon dioxide. It is a key component of natural gas and responsible for about a third of planetary warming just behind carbon dioxide.
- Accelerating and substantially reducing non-carbon-dioxide emissions globally, including in particular methane emissions by 2030 is necessary for humanity to have a shot at keeping average temperatures from rising beyond 1.5 degree Celsius by the end of the century, the agreement notes.
- The Global Methane Pledge to cut methane emissions 30% of 2020 levels by 2030 was signed on by nearly 150 countries at the COP-27 summit in Egypt. China and the U.S. have also agreed to address industrial methane emissions that result from natural gas production.
- India has resisted pressure to cut methane emissions on the grounds that most of its methane results from the agricultural sector. However, it has unveiled plans to make its energy production processes more efficient to reduce its release.
