Explain why a life cycle assessment (LCA) is not a purely objective process.

AQA GCSE Chemistry (8462) — 4.10.3 Using materials (Chem only) · Explain · 4 marks · View as Markdown

Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).

Model answer (4 marks)

1. Assigning numerical values to the effects of pollutants is not straightforward, as the impacts vary widely and are difficult to quantify.
2. Value judgements are inevitably required when interpreting and weighting these pollutant effects.
3. LCAs can be abbreviated or selective, with some life‑cycle stages omitted, which introduces bias.
4. The method can be misused to support marketing claims, further compromising objectivity.

Examiner tips

  • Use the exact phrases from the mark scheme (e.g., "allocating numerical values", "value judgements", "selective or abbreviated LCAs", "misused to support advertising claims").
  • Show the four points clearly, each addressing one of the scheme markers.
  • Keep the answer concise – 1–2 sentences per point.

Common mistakes

  • Confusing LCA with life‑cycle costing, or treating it as purely quantitative. Failing to mention that stages can be omitted or that the method can be misused for advertising. Using vague language such as "subjective" without linking to the specific reasons in the scheme.

Mark scheme (4 marks)

  1. Allocating numerical values to pollutant effects is not straightforward
  2. Value judgements are required (when assessing pollutant effects)
  3. Selective or abbreviated LCAs can be used / some stages can be left out
  4. LCAs can be misused, e.g. to support advertising claims

Key terms in this question

life cycle assessment (LCA)

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