Irene Conlan knew it was time for a career change when she began to act just a bit oddly.

"I had a laser printer and I could not bring myself to throw out the printer cartridges when I was done with them," Conlan said. "Instead, I put them in a box and hid them in my closet."

That was two years ago. Now Conlan, a former state health official in Arizona, is chairman of Cartridge Technology Network Inc., a family-run company in Herndon that has caught on to the fast-growing business of reconditioning laser cartridges. Conlan and her husband, former U.S. Rep. John Conlan (R-Ariz.), maintain residences in Reston and Scottsdale, Ariz.

Conlan's career change to entrepreneur from assistant director at the Arizona Department of Health Services involved more than the cartridges she hid in her closet. She said she became interested in cartridge recycling when she noticed that her agency tossed away hundreds each year. Some of the discarded cartridges looked like new and she thought there must be some further use for them.

She discovered there was a way to recycle cartridges. After hearing about a couple in California who had a small business recycling laser cartridges, Conlan visited them to learn the process. The couple told her that more offices were buying laser printers, increasing the number of cartridges that would be thrown away or recycled.

Conlan made up her mind then.

"I stood and did cartridges until I knew how, then I came back and taught my son," Conlan said. Kevin was then 16. "He said, 'OK mom, I'll be the technician. I'm better than you. And you run everything else."

Next, Conlan's older son Christopher and her husband, John Conlan, joined the rest of the family. John Conlan, who served in Congress from 1972 to 1976, is president of the company after giving up his law practice. Christopher Conlan, 20, took off time from college to help with the company. Other investors in the company are a group of Irene Conlan's friends, whom she declined to name.

For about half the retail cost of a new cartridge, companies such as Cartridge Technology take apart and clean used cartridges, replace old parts and refill the toner bin. In the Washington area, federal agencies and businesses have begun recycling laser cartridges, although recycled cartridges make up a small part of the market, which has sales of about $1.5 billion.

The company receives empty cartridges from clients and returns them within 48 hours after recycling.

Last week, Conlan and her family celebrated the opening of a new recycling lab at their Herndon corporate offices. The Conlans also have an office in Scottsdale, Ariz., and have affiliated businesses in 20 cities nationwide. The company employs about 20 people locally.

"I really feel we're at the right place at the right time with this business," she said. "It's got to grow, as people become more environmentally aware and ... try to save more money."

The Conlans would not reveal revenue figures for the last two years and they would not say how much the company spends to recycle a cartridge. John Conlan said the company recycled 500,000 cartridges in 1990 and 250,000 in 1989.

Each recycled cartridge costs the customer $35 to $49, depending on the number ordered. New cartridges retail for $90 to $180.

John Conlan said the company's research shows the United States used 11.17 million new laser cartridges (93 percent of the market) and 830,000 recycled laser cartridges (7 percent) in 1989. In 1992, Conlan projects the use of 24.85 million new cartridges (90 percent) and 2.75 million recycled cartridges (10 percent).

"They {new cartridges} weigh four pounds and cost around $100," John Conlan said. "Throwing them out is like throwing out your gold pen rather than putting in a refill."

Rebecca Hockman, assistant recycling coordinator for the Environmental Protection Agency, said the federal government has one contract with Cartridge Technology.

"There are a lot of these businesses popping up all over," Hockman said. "The demand seems to be there."