Review Reports

Reviewer Feedback

Revisions

What would be an appropriate and important extension of the study would be a follow-up several months to a year later to see if the educational value of having participated in the current study, with the self-descriptions of perceptions both of breast cancer risk and of potential harms from use of hair products, are associated with changes in behavior. In other words, did participating in the study educate the participants in ways that might have effects on subsequent behavior?  Information of this sort would greatly strengthen (or negate) the authors’ conclusions of a gap between intentions and behavior. 

This is a valid point, and we thank the reviewer for raising it. Unfortunately, given the cross-sectional study design used in the current study, we are unable to follow up with the participants. Nonetheless, we recognize that being part of an epidemiologic study such as this could be sufficient for behavioral change in this context, which might improve personal care product use behaviors. We have considered “cohort as intervention” bias as a possibility but did not discuss it as the current work did not engage with participants long term, so this form of bias may be a little less salient here.

We also noted: “Future studies should employ longitudinal designs, larger and more diverse samples, and include men and sexual and gender minority populations to examine prospective associations between BC risk perceptions, product use, and long-term health outcomes” (Lines 584-587, Page 15).

There is substantial material in the discussion about the social and cultural context of product use in Kenya, but less so about information on potential health risks. Do the authors have data on the source(s) of information that have led some women to have concerns about links between product use and negative health effects?

We did not explicitly ask participants why they may have concerns about links between product use and negative health effects as we wanted to know whether they did in fact have concerns.

One question included in the PCP Use Questionnaire asked was “When buying HAIR products to use at home, how often do you use smart phone apps and other resources that you can use to help you learn about potentially toxic chemicals in products before buying them?” And we were surprised to find that while most participants (66.3%) reported that they never/rarely/sometimes use apps or other tools to check for toxic chemicals before buying their hair products, almost a third (33.7%) reported that they usually or always did. These are the only data we collected regarding information sources that may have led some women to have concern about links between product use and negative health effects.

Authors state that differences in age at menarche differ especially between the no/low and very high and very high perceived BC risk groups.  Looking at Table 1, my reading indicates that those two groups have identical mean menarche ages, while the corresponding age for the high perceived risk group is higher.  Please clarify. (Results; Line 397-399) 

We thank the reviewer for noting this error, which has been corrected. Lines 234-237 on Page 5 has been revised to correctly summarize the difference observed:

“The mean age at menarche in the overall sample was 14.3±1.7 years and differed by latent classes, with participants in the high perceived BC risk class reporting a later age at menarche (14.6±1.8 years) than those in the no/low perceived BC risk class (14.1±1.6 years) and the very high perceived BC risk class (14.1±1.7 years) (P=<0.001).”

Additionally, we revised the discussion section that mentions these findings to improve clarity (Lines 469-471 on Page 13).

The discussion effectively points out the strengths and limitations of the study.

We thank the review for this feedback.

Reviewer Feedback

Revisions

The description of the instrument used to assess the perceived breast cancer risk associated with cosmetic hair products does not present its psychometric properties, nor does it indicate whether the tool was validated and/or adapted for the African population, specifically in Embu and Nakuru Counties, Kenya.

This point is well taken. We have now undertaken an analysis of the psychometric properties of the adapted BHBS subscale used in the current study and revised the methods (Measures section: Lines 123-159 on Pages 3-4; Statistical analysis section: Lines 204-236 on page 5) and added Supplementary Table 1 to show the item wording used in the original BHBS risk perception subscale and the wording in the questionnaire adapted to the Kenyan context. We also added a paragraph to the Results (Lines 317-325, Page 7) to highlight that internal consistency was acceptable.

The discussion does not compare the findings with those previously obtained in California using the same instrument; such a comparison would lend greater weight to the authors' assertions.

We thank the reviewer for this suggestion. We have added a comparison with the California validation study [Teteh 2019] and its replication among US Black breast cancer survivors [Teteh-Brooks 2025] to the Discussion (Lines 479-488, Page 13). The factor structure, the weakest loading items, and the most strongly endorsed item were consistent across settings, although internal consistency was lower in our Kenyan sample.

Both the introduction and the discussion could include data regarding the extent to which this factor contributes to the development of breast cancer.

We thank the reviewer for this comment. The Introduction (Lines 80-102 on Pages 2-3) provides a summary of existing epidemiologic evidence that may connect chemical exposures from personal care product use with breast cancer risk. As the focus of the current study is to evaluate associations between breast cancer risk perceptions and personal care product use, it does not seem appropriate to dive deeper into the connections between chemical exposures from these products and the development of breast cancer as that is beyond the scope of the current analyses.