- Correspondence to Dr A K Hedström, Institute of Environmental Medicine, Karolinska Institutet, Nobels väg 13, Stockholm 17177, Sweden;
- Received 2 September 2015
- Revised 6 January 2016
- Accepted 11 January 2016
- Published in print 1 May 2016.
- Published online 14 April 2016.
- Published first 3 March 2016.
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