SEEDS Internship : Exploring the bioaccessibility of toxic additive chemicals in consumer products

Microplastics (MPs) have been widely shown to be present in the freshwater and marine environment with concentrations up to 102000 particles m–3 in seawater and are also reportedly present in sediment, fish, soil, dust, air, food, and drink.  Such ubiquitous distribution of MPs in the environment and consumer products inevitably leads to human exposure to these particles, which has been confirmed by the recent detection of MPs in human blood, lungs, and stool.  However, animal studies have indicated MP exposure to elicit reproductive toxicity in oysters, reduced feeding in daphnia, and hepatotoxicity in zebrafish, as well as tissue accumulation and disturbance of lipid metabolism in mice.  Meanwhile, the toxicological impacts of human exposure to MPs are not well understood, which among others may be attributed to ethical constraints, strict biosecurity measures to handle human samples, and limited analysis techniques. While exposure to particles may lead to bioaccumulation, inflammatory lesions, and oxidative stress, there is also concern over the potential release of toxic chemical additives/adsorbed contaminants from MPs to human body fluids due to their small size and corresponding larger surface area.  A wide range of chemical additives such as plasticizers, pigments, flame retardants and fillers are often incorporated in plastics during manufacture to impart specific properties. Most of these additives, particularly in the plasticizers group, e.g. phthalate esters, have been found to cause adverse health effects including endocrine disruption, reproductive toxicity, neurotoxicity, hepatotoxicity, and cancer.   A recent study reported the leaching of toxic brominated flame retardants (BFRs) from polyethylene, polypropylene and polystyrene plastics to the in vitro human sweat, rendering them available for absorption, i.e. bioaccessible.  Bioacessibility is defined as the total amount of a chemical that is released from a solid matrix (e.g., human synthetic hair, dust, soil, MPs) into human or animal body fluids (e.g., saliva, gastric fluid, sweat) and thereby becoming available for absorption to the systemic circulation.  Consequently, this internship aims to study for the first time, the bioaccessibility of phthalate esters incorporated in microplastics arising from consumer products (e.g., human synthetic hair, adult novelties etc.,) upon contact with human synthetic body fluids. 

Work plan: Full-time

The following objectives is planned for the intern during the internship period: 
(a). Laboratory induction, health and safety, and familiarisation with project objectives (Week 1)
(b). Training on the preparation of human synthetic body fluids (Week 2).
(c). Training on microplastic production and characterisation of chemical additives from consumer products following standardised extraction and GC-MS protocol (Week 3 – 4). 
(d). Determination of bioaccessibility of toxic additives in consumer products (Week 4 – 6).
(e). Preparation of Report (Week 6 – 7). 
 

Work plan: Part-time

The following objectives is planned for the intern during the internship period:  (a). Laboratory induction, health and safety, and familiarisation with project objectives (Week 1) (b). Training on the preparation of human synthetic body fluids (Week 2). (c). Training on microplastic production and characterisation of chemical additives from consumer products following standardised extraction and GC-MS protocol (Week 3 – 4).  (d). Determination of bioaccessibility of toxic additives in consumer products (Week 4 – 6). (e). Preparation of Report (Week 6 – 7).