Environmental exposure to microplastics: An overview on possible human health effects

The ubiquity of microplastics in aquatic and terrestrial environments and related ecological impacts have gained global attention. Microplastics have been detected in table salt, drinking water, and air, posing inevitable human exposure risk. However, rigorous analytical methods for detection and characterization of microplastics remain scarce. Knowledge about the potential adverse effects on human health via dietary and respiratory exposures is also limited. To address these issues, we reviewed 46 publications concerning abundances, potential sources, and analytical methods of microplastics in table salt, drinking water, and air. We also summarized probable translocation and accumulation pathways of microplastics within human body. Human body burdens of microplastics through table salt, drinking water, and inhalation were estimated to be (0-7.3)×104, (0-4.7)×103, and (0-3.0)×107 items per person per year, respectively. The intake of microplastics via inhalation, especially via indoor air, was much higher than those via other exposure routes. Moreover, microplastics in the air impose threats to both respiratory and digestive systems through breathing and ingestion. Given the lifetime inevitable exposure to microplastics, we urgently call for a better understanding of the potential hazards of microplastics to human health.

https://findresearcher.sdu.dk:8443/ws/files/168676998/A_Review_of_Microplastics_in_Table_salt_Drinking_Water_and_Air.pdf

A Review of Microplastics in Table Salt, Drinking Water, and Air: Direct Human Exposure

Assessment of microplastics in freshwater systems: A review.

Microplastics pollution in different aquatic environments and biota: A review of recent studies

Microplastics in aquatic environments: Occurrence, accumulation, and biological effects.

The distribution of microplastics (MPs) was investigated in the sediments of five sampling sites from the northern Tunisian coast during June 2017. MPs were categorized according to type, colour and size. Representative MPs from the five sites were isolated for polymer identification using Fourier Transformed Infrared Spectroscopy in attenuated total reflectance mode (FTIR-ATR). Results showed that MPs were recovered, from all sediment samples, indicating for the first time, their extensive distribution in Tunisian coast. Concentrations varied from 141.20 ± 25.98 to 461.25 ± 29.74 items kg−1 dry weight. Fibres, fragments, Styrofoam®, pellets and films were the types registered in this study. With the exception of Menzel Bourguiba (MB), fibres significantly outnumbered plastic particles followed by fragments, Styrofoam®, films and pellets. The predominant colours are as follows: black > clear > white > red > blue > green for fibres, blue > white > clear > red > green > yellow > black for fragments, blue > white > black > clear for films while only white pellets and Styrofoam® were found. MPs particles ranged from 0.1 to 5 mm in length. A total of three polymer types were identified, polyethylene (PE), polypropylene (PP) and polystyrene (PS). Except for industrial pellets, the presence of MPs is likely due to the degradation of marine plastic debris accumulating in each site. This work provides original data of the presence of MPs in coastal sediments from Northern Tunisian coast.

Microplastics in sediments from the littoral zone of the north Tunisian coast (Mediterranean Sea)

Microplastics (MPs) in sediments from the complex lagoon-channel of Bizerte were investigated, for the first time, to evaluate the occurrence and abundance of MPs in Tunisia. After density separation in saline solution, MPs were counted by a stereomicroscope. The number of MPs was at the range of 3–18 items/g sediment (3000–18,000 items/kg dry sediment) and the most contaminated site was of Menzel Abderrahmane (MA) followed by Carrier Bay (CB), Menzel Jemil (MJ) and Channel of Bizerte (C). The MPs gathered during the survey varied in size from 0.3 to 5 mm, and appear in a variety of shapes and colours. The dominant shape was fibre (88.88% in MA, 91.00% in CB, 82.35% in C and 21.05% in MJ). The rest of MPs are fragments whilst no micro beads were found. Colours are clear, white, blue, green, red and black. Cities discharges, fishing activity and industrial production sites are the most likely sources of MPs. This first work provides original data on the presence of MPs that determines their bioavailability to organisms as seafood, and then possibly transfers of to human. The high MP concentrations registered in the complex lagoon-channel of Bizerte suggest that this site is a hotspot for MP pollution and there is an urgency to understand their origins and effects on marine life. The results will provide useful background information for further investigations.

The First Evaluation of Microplastics in Sediments from the Complex Lagoon-Channel of Bizerte (Northern Tunisia)

Microplastics in commercial molluscs from the lagoon of Bizerte (Northern Tunisia)

Microplastic (MP) concentrations were determined, for the first time, in surface sediment of seven streams around the lagoon of Bizerte (Northern Tunisia), using a saturated NaCl flotation technique. Microplastics were categorised according to type, colour and size using a stereoscopic microscope. Results showed that all sediment samples contained MPs. The greatest MP abundance was observed at Jedara stream (6920 ± 395.98 items kg−1 dry weight), while the lowest mean value was 2340 ± 227.15 items kg−1 dry weight at Khima stream. The highest numbers of MPs were from streams near populated areas and municipal and industrial effluent discharges. Samples were made up entirely of secondary MPs mainly fibres, followed by fragments and films. The predominant colours were as follows: black > clear > white > red > blue > green > yellow for fibres, white > blue > black > red for fragments and red > white > clear > green > blue = black for films. Microplastic particles in the samples ranged from 0.2 to 5 mm in length. FTIR analysis revealed that the abundant polymers were polypropylene and polyethylene. This work contributes to the growing evidence that MP contamination is widespread even in freshwater ecosystems and provides a baseline for future studies and risk assessments.

Microplastics in freshwater environment: the first evaluation in sediments from seven water streams surrounding the lagoon of Bizerte (Northern Tunisia).

We have assessed for the first time the current status of tributyltin (TBT) contamination in Hexaplex trunculus along Tunisian coastal waters. Two sampling campaigns have been performed in July 2004 and July 2007 at seven different sites. The snails were analyzed for imposex status, i.e. Imposex incidence, Relative Penis Length Index (RPLI) and Vas Deferens Sequence Index (VDSI), followed by the quantification of butyltins in their tissues. Imposex was detected in six populations from the 2004 samples and in five populations from the 2007 samples. The imposex incidence ranged from 0 (no imposex) to 100%, the RPLI from 0 to 56.7 and the VDSI from 0 to 4.4. TBT was also detected in six populations in 2004 and five populations in 2007. The concentrations ranged from 1.5 to 73.7 ng Sn g−1 dw in 2004 samples and from 1.2 to 23.9 ng Sn g−1 dw in 2007 samples. Temporal comparison of the data indicates some evidence of imposex recovery in most affected populations. Improvements in reduced body concentrations of TBT in both sexes were also seen in most stations. These TBT concentrations were only significantly correlated to imposex indices in samples from 2007 (r > 0.8, n = 7, p < 0.05). The present results will serve as a reference for long-term monitoring of butyltin contamination in the Tunisian coast, where TBT restrictions were not yet implemented.

/pdf/first-record-of-butyltin-body-burden-and-imposex-status-in-28ffnuxi10.pdf

Sami Abidli

Papers

Microplastics in sediments from the littoral zone of the north Tunisian coast (Mediterranean Sea)

The First Evaluation of Microplastics in Sediments from the Complex Lagoon-Channel of Bizerte (Northern Tunisia)

Microplastics in commercial molluscs from the lagoon of Bizerte (Northern Tunisia)

Microplastics in freshwater environment: the first evaluation in sediments from seven water streams surrounding the lagoon of Bizerte (Northern Tunisia).

First record of butyltin body burden and imposex status in Hexaplex trunculus (L.) along the Tunisian coast