The phrase "are substantial because" is correct and usable in written English.
It can be used to explain the reasons or justifications for something being significant or considerable.
Example: "The findings of the study are substantial because they provide new insights into the effects of climate change on biodiversity."
Alternatives: "are significant due to" or "are considerable as a result of".
The benefits are substantial because much less raw material, liquid steel, and energy are needed to make the same tonnage of cast product.
The stakes for consumers are substantial because federal law requires most Americans to have chosen insurance by March 31 or risk a fine.
The losses to society and the individuals are substantial because life expectancy is increasing, the retirement age is rising in many countries, and people are generally in good health (Axelrad et al. 2013; Vodopivec and Dolenc 2008).
The potential public health implications of these findings are substantial, because exposure to low levels of cadmium is widespread.
The public health implications are substantial, because COPD is projected to be the fourth leading cause of death worldwide by the year 2020 (Mannino 2005).
Most foodborne illness occurs as gastroenteritis, but the effect of nongastrointestinal illnesses and sequelae are substantial because they can result in hospitalization and, occasionally, death.
The jeopardy to privacy is substantial because DNA data in vast repositories could potentially become public.
But the effort for Microsoft is substantial because ARM and Intel chips have different "architectures" - in effect, speak different languages.
This is substantial because they are obviously meant to stand alone, that is, as a complete representation of the concept explored in the chapter.
Civilian deaths in the campaign have nonetheless been substantial because "military objects" have been targeted on the basis of extremely low-confidence intelligence.
One police supervisor said that the overtime earnings could be substantial because officers had been asked to work 12-hour shifts every day and were often working one weekend shift as well.
