Exposure to arsenic in drinking water has been associated with the onset of many diseases - HSC - SSCE Biology - Question 27 - 2020 - Paper 1
Question 27
Exposure to arsenic in drinking water has been associated with the onset of many diseases. The World Health Organization recommends arsenic levels in drinking water ... show full transcript
Worked Solution & Example Answer:Exposure to arsenic in drinking water has been associated with the onset of many diseases - HSC - SSCE Biology - Question 27 - 2020 - Paper 1
Step 1
Identify TWO features that contribute to the validity of the study
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Answer
Large Sample Size: The study involved 58,406 young adults, which provides sufficient data for meaningful conclusions and enhances the reliability of the results.
Consideration of Confounding Variables: The study took into account factors like age, sex, education, and socioeconomic status, which helps to isolate the effect of arsenic exposure on survival rates.
Step 2
Identify ONE feature that contributes to the validity of this study
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Age and Sex Consideration: By factoring in age and sex, the study can account for variations in survival that may be influenced by these demographics, leading to more accurate results.
Step 3
Discuss points for and/or against the hypothesis
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Survival rates are highest in those exposed to less than 90 µg L⁻¹ arsenic in both males and females, indicating a potential threshold effect below which arsenic may not significantly impact survival. Conversely, those exposed to higher arsenic levels showed a decrease in survival rates, suggesting that exposure increases mortality risk.
Step 4
Relate points made to the data
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The data supports these findings as it displays a decline in survival rates corresponding with increased arsenic exposure levels. The group with < 90 µg L⁻¹ exposure exhibits consistently higher survival percentages throughout the study duration.
Step 5
Describe trends
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Throughout the 11-year study, a progressive decline in survival rates is noted particularly in groups exposed to arsenic levels exceeding the WHO recommended threshold. This suggests a compounding effect of long-term arsenic exposure on health outcomes.
Step 6
Provide some relevant information
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Despite the decline in survival for higher exposure groups, those in the < 90 µg L⁻¹ category maintained a survival rate reduction of only 0.1% or less over the entire study duration, implying a relatively stable health status compared to their higher-exposed counterparts.
