Which of the following factors has NOT been identified as contributing to higher disability rates among ethnic minorities?

The factor that has not been identified as contributing to higher disability rates among ethnic minorities is underrepresentation in lower social strata. This suggests that simply being less represented in a lower social class does not directly lead to higher disability rates. In fact, many ethnic minorities may be overrepresented in lower socioeconomic positions, which often correlates more significantly with increased rates of disability.

On the other hand, the other factors listed, such as access to healthcare, socioeconomic status, and environmental factors, have been established as influential in contributing to disparities in health outcomes. Limited access to healthcare services can hinder timely diagnosis and treatment, leading to worse health outcomes. Socioeconomic status is also critical because individuals from lower socioeconomic backgrounds often face greater stressors and challenges that can contribute to poor health conditions, including disabilities. Environmental factors, such as living conditions and exposure to pollutants, can also disproportionately affect ethnic minorities, further contributing to higher disability rates.