Reference Handout for Science Club Members

1. Autism Research

What is Autism Spectrum Disorder (ASD)?

  • Definition: ASD is a neurodevelopmental condition characterized by challenges in social interaction, communication, and restricted/repetitive behaviors.
  • Prevalence: Estimated at 1 in 36 children in the U.S. (CDC, 2023).
  • Diagnosis: Typically identified in early childhood; diagnosis based on behavioral assessments.

Causes and Risk Factors

Factor Description
Genetics Over 100 genes linked to ASD; heritability estimated at 50–80%.
Environmental Prenatal exposure to air pollution, certain medications, and infections.
Brain Development Differences in neural connectivity and synaptic function.
Epigenetic Changes DNA methylation and histone modification may influence gene expression.

Recent Advances in Research

  • Genomics: Whole-genome sequencing has identified rare and common variants associated with ASD.
  • Neuroimaging: MRI studies show atypical connectivity in regions controlling social behavior.
  • Early Intervention: Evidence supports improved outcomes with therapies initiated before age 3.

Neural Connectivity in ASD

Figure: Example of altered neural connectivity in ASD (for illustration purposes).

Surprising Facts

  1. Autistic traits are present in the general population: Research shows that traits associated with ASD exist on a continuum in all people (Robinson et al., 2021).
  2. Females with ASD are often underdiagnosed: Girls may mask symptoms, leading to later or missed diagnoses.
  3. Some individuals with ASD have exceptional abilities: Known as “savant skills,” these can include remarkable memory, calculation, or artistic talent.

Global Impact

  • Prevalence: Rising rates reported worldwide; increased awareness and better diagnostic tools contribute.
  • Social Inclusion: Many countries lack adequate support systems for autistic individuals.
  • Economic Costs: Estimated lifetime cost per individual can exceed $2 million (Buescher et al., 2014).

Data Table: ASD Prevalence by Region (2023 Estimates)

Region Prevalence (per 1,000) Notable Trends
North America 27 Increased awareness, early diagnosis
Europe 15 Variation in diagnostic criteria
Asia 8 Underreporting, stigma
Africa 2 Limited data, low awareness

2. Plastic Pollution in the Deep Ocean

Discovery & Extent

  • Recent Findings: Microplastics and macroplastics have been found in the Mariana Trench and other deep-sea environments (Peng et al., 2020).
  • Sources: Land-based runoff, fishing gear, and shipping contribute to oceanic plastic debris.

Plastic Debris in Deep Ocean

Figure: Example of plastic debris found in deep ocean environments.

Mechanisms of Transport

  • Ocean Currents: Carry plastics from surface to deep-sea.
  • Biological Transport: Marine organisms ingest plastics, which are then deposited in sediments.
  • Sinking: Plastics become heavier due to biofouling and sink.

Environmental Implications

Impact Area Description
Marine Life Ingestion causes physical harm, starvation, and death.
Food Web Disruption Microplastics accumulate in organisms, affecting higher trophic levels.
Chemical Pollution Plastics leach toxic additives (e.g., phthalates, BPA) into water.
Habitat Alteration Plastics change sediment structure and reduce oxygen levels.

Microplastics in Deep-Sea Sediments

Figure: Microplastics observed in deep-sea sediments.

Surprising Facts

  1. Plastic pollution has reached the world’s deepest point: Microplastics were found at 10,900 meters in the Mariana Trench (Peng et al., 2020).
  2. Deep-sea organisms ingest plastics: Even amphipods living at extreme depths have been found with plastic particles in their guts.
  3. Plastic debris can persist for centuries: Low temperatures and lack of sunlight slow degradation rates in the deep ocean.

Data Table: Plastic Pollution in Deep-Sea Trenches (Peng et al., 2020)

Trench Depth (m) Microplastic Concentration (particles/kg sediment) Notable Finding
Mariana Trench 10,900 13,000 Highest recorded
Atacama Trench 8,000 7,200 Multiple polymer types
Kermadec Trench 10,000 4,500 Ingestion by amphipods

Global Impact

  • Ecosystem Health: Threatens biodiversity and disrupts nutrient cycling.
  • Human Health: Microplastics enter seafood, posing potential risks.
  • Economic Costs: Impacts fisheries, tourism, and marine industries.
  • International Response: UN and national policies aim to reduce plastic waste; effectiveness varies.

Environmental Implications

  • Long-Term Effects: Plastics act as vectors for invasive species and toxic chemicals.
  • Irreversible Damage: Deep-sea habitats are slow to recover due to low energy and slow biological processes.
  • Research Needs: Improved monitoring, biodegradable alternatives, and global cooperation.

3. References

  • Peng, X., et al. (2020). “Microplastics contaminate the deepest part of the world’s ocean.” Geochemical Perspectives Letters, 14, 1-5. Link
  • CDC (2023). “Autism Spectrum Disorder (ASD) Data & Statistics.”
  • Robinson, E.B., et al. (2021). “Autistic traits across the population: A spectrum.” Nature Reviews Neuroscience.

End of Handout