Dear Doctor: Ever since the news about lead in the drinking water in Flint, Michigan, I've wondered about the water in my own home. I live in Oklahoma, and our house was built in 1988. Should I be worried?

Dear Reader: You've asked a timely question that, unfortunately, has a complex answer. Let's start with why the presence of lead in our environment -- whether in the water, air or soil, or in the products we use or come into contact with -- is of grave concern.

Lead is a highly toxic metal that has a detrimental effect on virtually every system in the human body. Children, with their developing brains and nervous systems, are particularly vulnerable to the effects of lead. The amount of lead that an adult can tolerate with minimum ill effect can cause significant damage to a child. The challenge is that until it becomes acute, lead poisoning virtually has no symptoms.

Lead causes anemia, hypertension and damages the kidneys and the reproductive system. Even low blood levels of lead affect the development of the brain and nervous system. In children it can result in lower IQ, hearing problems and behavioral changes like reduced attention span. The neurological damage caused by lead is believed to be irreversible.

Exposure to lead is bio-accumulative. That means the lead you ingest stays in the body and, as exposure continues, blood levels increase. And although the health crisis in Flint has put the spotlight on lead in water, the presence of lead-based paint in older homes poses the most common risk. It's a topic we've addressed in a previous column.

As for your situation, there is some good news. In 1986, two years before your home was built, the Safe Drinking Water Act significantly reduced the amount of lead permitted for use in plumbing fixtures, including pipes and solder. However, it wasn't until 2014 that the most stringent regulations regarding the use of lead in water delivery systems went into effect.

You will also want to find out whether your water supplier is in compliance with federal lead contamination regulations. Federal law requires regular testing for contaminants. The results are published in a document called the Consumer Confidence Report. Ask for a copy. Should you wish to test your own water, the Environmental Protection Agency has a list of certified labs on its website. Most home improvement stores also sell water-testing kits.

If you believe your water supply is contaminated with lead, the EPA suggests the following:

-- Flush your pipes for 30 seconds to two minutes before using water for drinking or cooking.

-- Use only cold water for drinking or cooking. Hot water may contain higher levels of lead.

-- According to the EPA, it is safe to bathe or shower in water that contains lead, as it is not absorbed through the skin.

-- Consider installing a water filtration device that is certified to remove lead.

We recommend a visit to www.epa.gov, where you'll find a wealth of information and resources.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o Media Relations, UCLA Health, 924 Westwood Blvd., Suite 350, Los Angeles, CA, 90095. Owing to the volume of mail, personal replies cannot be provided.)

Dear Doctor: I love swimming and doing water exercises in the pool. The problem is that I tend to get painful cramps in my legs and feet. Is there anything I can do to avoid them? Does my age (I'm 69) have anything to do with this?

Dear Reader: Muscle cramps in the legs -- the calf and thigh, as well as the feet -- are a fact of life for some of us who exercise. And while there are many theories as to why they occur (many of them presented quite forcefully as fact), the truth is, we don't really know the cause. It does appear that cramps, or muscle spasms, can become more common as we age. That's particularly true of leg cramps that occur at night, during sleep. For others, as you have discovered, they can intrude into the activities of daily life.

What's happening is that, due to a nerve malfunction, the muscle fibers suddenly contract and don't release. Unless you've ever lived through a muscle spasm (sometimes it's called a charley horse), you can't understand just how helpless you feel and how painful it is. And while the spasm itself typically ends relatively quickly, that area of the muscle may feel tender for a day or so.

If you decide to check in with your family doctor regarding the onset of these muscle spasms, he or she will most likely begin with a physical examination of the area involved. Your doctor will also collect the information needed to rule out any underlying disease or condition that could be the cause of the spasms. This includes diabetes, kidney disease, heavy drinking or alcoholism, and peripheral artery disease. The latter, which Dr. Ashley covered in a recent column, is a condition in which certain arteries, including those in the legs, become narrow. Pregnant women are also prone to muscle cramps, particularly in the final months before delivery.

Other factors in persistent leg cramps can include a pinched nerve, flat feet, muscle fatigue from overuse and an imbalance of essential minerals such as calcium and magnesium. Muscle cramps can also be a side effect of certain medications, such as diuretics and statins.

We see two potential factors associated with muscle spasms in your situation. One is muscle overuse, and the other is cold temperature. Do the cramps occur in the later stages of your workouts? If so, try taking a break before you reach that danger zone. Hop out of the pool, get something to drink, warm up your legs with a quick walk. Do some stretches and massage the muscles before getting back into the pool.

Another area of agreement around muscle spasms is the importance of potassium, calcium and magnesium in neural health. Dark leafy greens are a good source of magnesium. Potassium-rich foods include sweet potatoes, bananas, broccoli, halibut, cantaloupe and orange juice.

When a cramp does occur, gently massage the affected area and gradually stretch the muscle. It's possible for a cramp to last up to a minute or more, so be patient. And if the cramps are severe enough to interfere with daily life, please do get in touch with your doctor.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o Media Relations, UCLA Health, 924 Westwood Blvd., Suite 350, Los Angeles, CA, 90095. Owing to the volume of mail, personal replies cannot be provided.)

Dear Doctor: My family tries to limit dairy products; it just doesn't make sense to me that, marketing aside, humans should need milk from another species. But now I read that non-cow milk may be linked to shorter kids. Why would that be?

Dear Reader: Your question is a logical one. The milk from breastfeeding is necessary for infant growth across all mammalian species, and humans are the only species of mammal that not only raises their young using the milk of another animal, but also consumes this milk in later life. So while it doesn't make biological sense to drink cow milk, eat cheese, or have creams and yogurt well beyond the time of breastfeeding, does it have a positive or negative effect on our bodies? And, if cow milk has an effect, what are the effects of cow milk substitutes like soy milk, almond milk and goat milk?

A 2017 article in the American Journal of Clinical Nutrition, which received widespread news coverage, attempted to answer these questions. The authors asked 5,034 Canadian parents of children ages 2 to 6 about their children's daily consumption of cow milk and non-cow milk products. Based on the parents' answers, 4,632 children were identified as cow milk drinkers, and 643 were identified as non-cow milk drinkers. (Note that some non-cow milk drinkers also drank cow milk.) There were no appreciable differences between the two groups of children, except for height.

Each daily cup of non-cow milk was linked to a height difference of 0.4 centimeter. That is, children who drank three cups of non-cow milk a day were 1.2 centimeters (approximately 1/2 inch) shorter than children who drank no non-cow milk. Similarly, children who drank three cups of cow milk a day were 1.5 centimeters taller than those who drank 3 cups of non-cow milk.

Here's a possible explanation: The cow milk proteins, casein and whey, have been linked to an increase in size. Also, cow milk contains insulin-like growth factor-1 (IGF-1), which leads to the formation of more bone and cartilage and thus greater height. IGF-1 is also found in goat milk. Note that this study lumped goat milk with soy, almond and other non-mammalian milk, so goat milk may not actually have the height correlation seen with these non-animal milks.

Another possible explanation is that plant-based milks do not contain as much protein and fat as mammalian milk. Thus, children who drink these types of milks don't get the calories or protein needed for greater growth.

Lastly, children who have food allergies are less likely to drink cow milk. Because food allergies have been associated with decreased height and weight, the allergies themselves may be a factor.

In summary, there could be myriad reasons why children who drink cow milk are taller than those who drink plant-based milks, but the fact remains that this seems to be the case. If you're worried that avoiding dairy products will interfere with your child's height, but you're opposed to dairy products for personal or health reasons, I'd recommend you ensure that your child consumes plenty of protein in other ways -- and that your pediatrician keeps a close eye on your child's development.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o Media Relations, UCLA Health, 924 Westwood Blvd., Suite 350, Los Angeles, CA, 90095. Owing to the volume of mail, personal replies cannot be provided.)