This is a very comprehensive report about Effective dose and clarification of its use.
Line 491, para 14.Concerning DDREF, ICRP 131 (pages 14, 80+) included a description of mechanisms for the DDREF components DEF and DREF being different in concept and value for various tissues. It seems appropriate to allude to these separate components, with reference to that publication.
Somewhere, perhaps in Section 4.3 (line 1579), it would be useful to reference the recent UNSCEAR 2017 report Annex B. This described epidemiological studies of some low-dose-exposed populations living in high-background radiation areas, as well as other low-dose-exposed groups. These models for chronic exposures were discussed extensively in terms of their value and caveats.
In terms of style, many sentences in the text are lengthy; consider keeping sentences shorter by splitting some to make easier reading and understanding. Also, the list of 22 Main Points is very useful albeit long. It may be clearer to group them using a few subheadings, and/or put the bolded Points for the new changes first.
Line 809. Six years ago is hardly recent.
Line 822. Adjustments plural.
Line 879. Co-60 and megavoltage x-rays are becoming the more-conventional reference radiations.
Line 2145. Correct Shrimpton spelling.