DEAR DR. ROACH: I have had cancer twice, and I try to do everything in my power to prevent a recurrence or a new cancer — exercising daily and following a strictly healthy diet that includes lots of vegetables and fruits, and buying organic produce whenever possible. Since most of our fresh foods, i.e. vegetables and fruits, are placed in plastic bags when shopping and our poultry/meat, potatoes, cheeses, breads, frozen vegetables and fruits, as well as packaged nuts and seeds, come in plastic wrap or bags, I’m beginning to question if, since plastic has been proven as a carcinogen and apparently our foods absorb the dangers of the plastic, are we doing ourselves more harm than good? — Anon.

ANSWER: Trying to eat well is very important, especially after a diagnosis of cancer, because some foods help reduce cancer risk, especially fresh (or frozen) vegetables and fruits; others, such as processed meats or meats that have been charred, increase cancer risk slightly.

There are many different forms of plastics, but the plastics that are allowed to be used with food have not been proven to increase cancer risk. Foods stored in plastics at room temperature and below, including freezing, generally do not absorb dangerous chemicals from plastic. One possible exception to this is a chemical called bisphenol A, abbreviated BPA. This chemical has been shown to be an “endocrine disrupter,” acting like an estrogen. The amount of BPA considered safe remains controversial, with most authorities stating that the low level found in food is not enough to worry about. People who wish to avoid BPA should avoid plastics marked with recycling codes 3 and 7, and cans lined with plastic. Heating plastics can release potentially toxic chemicals, so it’s best to avoid doing so. If the plastic melts, discard the food and the plastic.

People who work in the industry making plastics need protective equipment, since the chemicals used to make finished plastic consumer goods can be toxic.

DEAR DR. ROACH: My partner develops a tingling hand in bed at night. It keeps him awake. What type of doctor should we see? — N.C.

ANSWER: The most likely cause of tingling hand at nighttime is carpal tunnel syndrome. If that were the case, he should notice the numbness in the thumb, index and middle finger, and the half of the ring finger closest to the middle finger. That is the area where sensation is supplied through the median nerve, which runs through the carpal tunnel (a ring of bones and connective tissue). If the pressure inside that ring is too high, the median nerve can be compressed and cause tingling.

With progressive damage, weakness and atrophy of the muscles can occur. Any primary care provider should be able to make the diagnosis most of the time; occasionally, an expert, such as a neurologist, orthopedic surgeon or rheumatologist, is necessary. An EMG test uses needles to measure the nerve impulses, and this can confirm the diagnosis. A definitive EMG test is recommended prior to surgical treatment, which is necessary if conservative treatments fail.

The cubital tunnel, up in the elbow, also can compress a nerve to the hand, but in this case it’s the ulnar nerve, which provides sensation to the little finger and the half of the ring finger next to it. It’s a much less common cause of tingling but is also diagnosed clinically, and confirmed with an EMG test if necessary.

Dr. Roach regrets that he is unable to answer individual letters, but will incorporate them in the column whenever possible. Readers may email questions to ToYourGoodHealth@med.cornell.edu or request an order form of available health newsletters at 628 Virginia Dr., Orlando, FL 32803. Health newsletters may be ordered from www.rbmamall.com.