Before sitting down to dinner with the family, wash your hands - and please turn off all pagers, cell phones, and other forms of communication with the outside world. The average household exchanges roughly 115 messages a week, according to the new Household Messaging Study by Pitney Bowes, and one out of five handles as many as 240 messages weekly. These high-volume households often have high education levels, above-average discretionary incomes, family members who telecommute, and teenagers who introduce new technologies to their parents. They also receive almost three times as many messages as they send, an indication that businesses are courting them with products and services. And thank your job for helping to keep those lines of communication clogged: 18 percent of all messages sent and received by the average home each week are work-related.