If clinical laboratory science (medical technology) appeals to you more than environmental science and you feel you can do well in the "hard sciences" needed for this career if you apply yourself, then I would choose medical technology. When you evaluate two seemingly equal options when making a life altering decision you have to go with your instinct. In the end, you have to love what you do.

Medical technologists/Clinical laboratory scientists must have a strong background in the biomedical/biological sciences (a BS degree in either medical technology, biological science, microbiology, biochemistry or a related field). In addition you must complete a clinical internship (including coursework and clinical rotations through hematology, chemistry, microbiology, immunology, and immunohematology). The clinical internships (aka med tech programs or MT training programs) are usually around a year in length and are fairly rigorous. Because these hospital based internships are closing down at a rapid rate due to budget cuts and lack of education about the field, they are becoming more competitive. So, if you choose the MT route you will want to go beyond just meeting the minimum standard (using either GPA, involvement, or experience to stand out to program directors).

Also, I believe you have the salary information switched. Medical technologists don't generally make what most consider to be "big bucks" whereas environmental scientists may (depending on education). MTs make between $40K and $70K annually (average around $55K) whereas environmental scientists make between $33K and $105K (average around $69K). Although, salaries for MTs are expected to rise over the next 5-15 years as a result of a growing shortage of laboratory professionals. There aren't near enough MTs entering the field to replace the retiring baby boomer generation and the average MT is over 50 years old.

Never settle study what you need to study so you can earn a degree in what you really want to do. Push yourself to a limit though you have to be happy with what you are studying.