Introduction to microplastics and health Implications

1. INTRODUCTION TO MICROPLASTICS AND HEALTH
IMPLICATIONS

2. INTRODUCTION
 Provide an overview of microplastics and their interactions with human
health.
 Identify existing research gaps and regulatory challenges related to
microplastics.
 Establish a foundational understanding to guide future work in microplastics
and health.
 Emphasize the complexity and urgency of addressing microplastic pollution.
 Highlight the importance of cross-sectoral collaboration for effective
solutions.
 Set the stage for a series of webinars to deepen knowledge and inform
policy.

3. WHAT ARE MICROPLASTICS?
 Defined as plastic particles smaller than 5 millimeters in length.
 Exhibit diverse shapes: irregular fragments, spheres, fibers, and films.
 Vary in polymer composition and surface characteristics, affecting
behavior and toxicity.
 Include microfibers, which are among the least studied microplastic
types.
 Overlap in size and abundance with natural microparticles, complicating
detection and impact assessment.
 Can extend down to nanoscale sizes, increasing complexity in analysis
and health effects.

4. SOURCES OF MICROPLASTICS
 Originate from primary sources (manufactured small
plastics) and secondary sources (breakdown of larger
plastics).
 Significant contributors include tire wear particles,
synthetic clothing fibers, and macroplastic degradation.
 Estimated that approximately 8 million metric tons of
microplastics enter the environment annually.
 Sources are diverse and widespread, making precise
quantification challenging.
 Atmospheric deposition and ocean currents
contribute to global distribution.
 Microplastics can carry chemical additives and adsorb
environmental pollutants.

5. ENVIRONMENTAL PRESENCE
AND PERSISTENCE
 Microplastics are found ubiquitously in water, soil, air, and
even deep ocean sediments.
 Their resistance to degradation leads to accumulation
and persistence over time.
 Concentrations can vary widely by location, with some
deep-sea areas showing unexpectedly high levels.
 They can act as vectors for invasive species, pathogens,
and hazardous chemicals.
 Environmental aging processes alter microplastic
properties, influencing toxicity and transport.
 Their presence poses risks to biodiversity and ecosystem
health

6. PATHWAYS AND
EXPOSURE ROUTES
 Humans are mainly exposed through inhalation of airborne microplastics and ingestion via food and water.
 Microplastics have been detected in human organs, blood, urine, and stool samples.
 Particle size and shape influence the ability to cross biological barriers and accumulate in tissues.
 Exposure assessment is complicated by the diversity of microplastic types and environmental matrices.
 Other potential exposure routes include dermal contact and medical devices, though less studied.
 Understanding exposure pathways is critical for assessing health risks.

7. HEALTH CONCERNS AND
EFFECTS
 Physical impacts resemble those caused by particulate
matter inhalation, potentially causing inflammation.
 Toxicity may arise from plastic additives, residual
monomers, and adsorbed environmental chemicals.
 Microplastics can disrupt gut microbiota and immune
system responses.
 Potential reproductive and physiological effects observed
in animal studies.
 Smaller particles (nanoplastics) are more likely to
translocate into tissues and cause cellular effects.
 Long-term health effects in humans remain largely
unknown due to limited data.

8. KNOWLEDGE GAPS IN HUMAN HEALTH EFFECTS
 Limited availability of high-quality toxicology
studies that mimic realistic human exposures.
 Need for better characterization and use of
environmentally relevant microplastic particles in
studies.
 Lack of long-term exposure data, especially for
nanoplastics and complex mixtures.
 Insufficient understanding of biodistribution, fate,
and immunotoxicity of microplastics in humans.
 Challenges in linking exposure levels to specific
health outcomes.
 Need for interdisciplinary collaboration to address
complex research questions.

9. ANALYTICAL CHALLENGES
 Detecting and quantifying microplastics in complex
matrices like air, water, food, and biological tissues is
difficult.
 High risk of contamination during sampling, processing,
and analysis.
 Lack of standardized, validated methods hampers
comparability of results across studies.
 Need for development and adoption of reference
materials and quality assurance protocols.
 Analytical limitations restrict ability to measure
nanoplastics and characterize chemical additives.
 Advances in instrumentation and methodology are
critical for progress.

10. REFERENCE MATERIALS AND STANDARDS DEVELOPMENT
 Polymer kits (e.g., from Hawaii Pacific University) have been developed to support method development.
 International organizations like ISO and ASM are working on standardizing test methods.
 Reference materials must be environmentally relevant, including aged and mixed polymer types.
 Production of microplastic particles suitable for toxicology studies is advancing but remains challenging.
 Standardization efforts facilitate data comparability and regulatory acceptance.
 Collaboration among academia, industry, and government is essential for progress.

11. REGULATORY AND
RESEARCH EFFORTS
 WHO assessments (2019, 2022) found low evidence
for adverse human health effects due to data
limitations.
 European and US agencies are funding research and
fostering international collaborations.
 Regulatory frameworks are evolving, with some
regions adopting hazard-based approaches.
 Coordinated, cross-sectoral strategies are needed to
address microplastic risks effectively.
 Research priorities include exposure
characterization, toxicology, and risk assessment.
 Engagement with stakeholders across sectors is
critical for policy development.

12. FINDINGS FROM CALIFORNIA STATEWATER BOARD
 Review of in vivo and in vitro studies revealed some evidence of reproductive and physiological effects in
rodents.
 Particle size is a key factor; smaller particles more readily translocate into tissues.
 Traditional dose-response models may not adequately capture microplastic toxicity mechanisms.
 Biomarkers of inflammation and oxidative stress are commonly observed endpoints.
 Quality of studies varies; many do not meet regulatory guideline standards.
 More robust, standardized studies are needed to inform risk assessments.

13. EXPOSURE DATA AND
GEOGRAPHIC DISTRIBUTION
 Microplastics have been detected in various US
environments, including urban and rural areas.
 Limited data exist on geographic variability in human
exposure levels.
 Measuring body burden and linking exposure to health
outcomes remains challenging.
 Existing databases track some chemicals associated with
microplastics but not microplastics themselves.
 Exposure assessments often lack harmonized
methodologies.
 Improved biomonitoring and population-level studies are
needed

14. COLLABORATIVE AND MULTISECTORAL SOLUTIONS
 Collaboration across government, academia, industry, and health sectors is essential.
 Leveraging existing data and international scientific collaborations accelerates progress.
 Emphasis on prevention strategies such as reducing plastic production and using safer alternatives.
 Simplifying and standardizing recycling programs can reduce microplastic generation.
 Public engagement and education are important for behavioral change.
 Policy development should be informed by robust science and stakeholder input.

15. FUTURE DIRECTIONS
 Improve toxicology studies using
environmentally and human health
relevant microplastic types.
 Develop biomonitoring tools and
conduct population-level exposure
studies.
 Advance analytical methods and establish
standardized protocols.
 Expand interdisciplinary collaborations
involving scientists, engineers,
statisticians, and health professionals.
 Increase funding and support for long-
term research initiatives.
 Foster international cooperation to
harmonize research and regulatory
approaches.

16. SUMMARY AND CLOSING REMARKS
 Microplastics represent a complex and pervasive environmental and health challenge.
 Current evidence on human health impacts is limited but raises concerns.
 Ongoing research, standardization, and collaboration are critical to advance understanding.
 Prevention and mitigation require coordinated efforts across sectors and regions.
 Public awareness and policy engagement are key to driving change.
 The webinar series will continue to address emerging questions and inform future actions.