About me

I am an Associate Professor in Toxicology and research group leader at IMM. The research in my group is mainly about understanding the the toxicity of nanoparticles and underlying mechanisms. Another focus is the development of new cell-based assays to enable replacement of animal experiments (3R). I teach in the Master's Programme in Toxicology and have for many years worked with issues related to the environment and sustainable development at KI.

Research description

The main focus of my research group is to study toxic effects of various small particles following exposure of cultured lung cells, and to find out why the particles are harmful. Another focus is to develop and test new cell models such as co-culture of different cell types, use of reporter cells and exposure of cells to airborne particles (air-liquid interface exposure). Ongoing studies deal with nanoparticles from different types of transport modes, micro- and nanoplastics and effects of particles related to 3D printing. Another project focuses on skin allergy and cell models to understand risks with different chemicals or medical devices.

Harmful effects of nanoparticles from different types of transport. In the EU project "nPETs", we study nanoparticles that are formed by different modes of transport (road traffic, subway, air, etc.). More info here: https://www.npets-project.eu/. The project includes comparing toxic effects from nanoparticles from different sources using different cell methods such as exposure of cells in the "air-liquid interface". We have recently compiled knowledge about how nanoparticles (also called ultrafine particles) are formed and what harmful effects are known today.

Read more on health effects and toxicity of particles here : Air & Environment (naturvardsverket.se) or in the review articles:

Toxicity and health effects of ultrafine particles: Towards an understanding of the relative impacts of different transport modes - ScienceDirect

Transport-related airborne nanoparticles: Sources, different aerosol modes, and their toxicity - ScienceDirect

Harmful effects of micro- and nanoplastics. In society today, there is a lot of focus on so-called micro and nanoplastics – small plastic fragments that are found in air, water and in the food we eat. The main source of microplastics in the air has been reported to come from textiles indoors and wear from tires is estimated to be an important source outdoors. In an ongoing project, we are studying whether micro- and nanoplastics can cause harmful effects on cultured cells. The first results show low toxicity in short-term studies.

Toxic effects of welding particles and particles from 3D printing. In projects that are mainly financed by VINNOVA, performed in collaboration with KTH and several industrial partners, we study the toxic effects of welding particles and of powders used in so-called "3D printing". Among other things, we have shown that nanoparticles from different welding methods differ significantly in toxicity. New welding wires have been developed by industry partners, and we have shown that particles formed during welding with these release significantly less hexavalent chromium and they are also not as toxic as particles generated from welding with the traditional wires (see e.g McCarrick et al., 2021). See Swedish summary below! In studies on powders used in 3D printing, or particles formed in the process, we have so far seen limited toxicity (see e.g. Vallabani et al., 2022).

Mechanistic studies and in vivo-in vitro dose comparisons. In several projects, we try to understand more about what happens to small particles in the body or in cells and how different cells are affected. Among other things, we have used reporter cells (ToxTracker) which can effectively show whether nanoparticles are genotoxic (see e.g. McCarrick et al., 2020). We have studied gold nanoparticles considered insoluble in cells and shown that they can dissolve in macrophages, especially if they are very small (5 nm, see McCarrick et al., 2021). An interesting question is how to be able to compare the dose that a person is exposed to via inhalation, with the dose used in cell studies. We have studied this and used so-called MPPD modelling. Read more in McCarrick et al., 2022 here: Modelled lung deposition and retention of welding fume particles in occupational scenarios: a comparison to doses used in vitro | SpringerLink

Cell-based test for determining the allergenic potency of chemicals. Anyone who has skin contact with allergenic substances can develop contact allergy (sensitisation) and those who have become allergic develop eczema after subsequent contact with the substance. In a project, chemicals and medical devices are studied using different cell models. In a first article, we show that co-culture of skin cells and immune cells could be successful (Karri et al., 2021).


2016: Associate Professor in Toxicology at the Institute of Environmental Medicine (IMM)

2006: Dr.Med.Sci., Karolinska Institutet. Scientific field: Medicine/ Environmental medicine. Thesis title: Particularly Harmful Particles? - A study of airborne particles with a focus on genotoxicity and oxidative stress. 

2001: M.Sci. Chemistry from Karlstad University. Main subjects: Chemistry (Karlstad University), Environmental Sciences (Karlstad University), Human Biosciences/Biology (University of Newcastle, Australia) Toxicology (Karolinska Institutet)


Academic honours, awards and prizes

Reciever of KI’s Sustainability Award 2023

Receiver of stipend from ”Konung Carl XVI Gustafs 50-årsfond för vetenskap, teknik och miljö”, 2012

Main funding

EU Horizon 2020. nPETs: Nanoparticle emmissions from the transport sector (2021-2023). https://www.npets-project.eu/

KID-funding. Health effects of nano- and microplastic particles - studies using advanced cell models (2021-2023)

Naturvårdsverket. MixIT: Towards quantifying impacts of microplastics on environmental and human health (2019-2023)

VINNOVA. Health risks related to additiv manufacturing (3D-printing), HÄMAT (2018-2024)

VINNOVA. Project title "Minimized risk for release of harmful substances from welding fume in FCW stainless steels" (2018-2020)

FORMAS. Project title: "Nanoparticles in the lung – how can bio-solubility be measured and used in modelling?" (2018-2020)

VR. Project title: "Development of a novel cell-based assay for determination of skin sensitizing potency of chemicals" (2018-2020)

VR. Project title: “Nano-Cell interactions: DNA damage of well characterized metal and metal oxide nanoparticles investigated by using high-throughput comet assay and reporter cell lines” (2015-2018)