A pair of grim and, for television, largely uncompromised movies compete on the networks tonight. One is a kind of "China Syndrome" and the other something like "Ordinary People," but there are things about each that are superior to the big bow-wow theatrical movies that may have helped inspire them.

NBC's "Bitter Harvest," at 9 on Channel 4, is a gripping and conscientious film based on a toxic-chemical scandal that ravaged Michigan (the state is not identified in the film) in the middle and late '70s. A foul-up at a chemical plant resulted in large quantities of PBB (polybrominated biphenyl) being introduced into the food chain through cattle feed.

The ensuing scandal dragged on for years in the courts and was the subject of an excellent PBS (no relation to PBB) documentary. But a dramatization like NBC's is really more effective as alarmist literature because it personalizes the devastating toll taken by this classic technocratic outrage.

ABC, meanwhile, has a softer social message, but a fairly timeless one, in "Freedom," at 9 on Channel 7, a film about a 16-year-old girl's troubled relationship with her mother. The Sensitivity Rhetoric in the script is a bit hard to swallow, but some of the performances, especially Mare Winningham's as the daughter, do much to compensate and help the story through some torturous soul-searching.

"Bitter Harvest" chronicles, among other matters, the true television coming-of-age of Ron Howard, who began his public odyssey years ago as a child actor ("The Andy Griffith Show"), had the good sense to abandon the desperation of "Happy Days" last year, and here comes across as adult, emphatic, almost strapping, and totally dedicated to his role as an embattled farmer.

The film falls neatly into two genres: the based-on-fact but after-the-fact soulful expose, and the man-against-the-system idea which has become one of the most abiding themes of contemporary TV movies. Richard Friedenberg's script could be broken down into an outline that has been used time and time again -- introduction of the crisis, realization of the crisis by the afflicted, the hopeless phase, the turning point wherein the hero decides to fight back, the fight itself, the vindication -- yet, impressively, it works.

Howard plays farmer Ned Devries who, with his "city girl" Kate (the very natural Tarah Nutter), has taken over Dad's farm, raising dairy cattle. vIn an early, show-stopping scene, the couple assist in the delivery of a calf. iBut the calf becomes inexplicably ill, cows begin to keel over in the meadow, and even the young couple's own baby develops a mysterious skin rash.

Before the film is over, Devries will be ignored and rebuffed by state agriculture officials and forced to take action on his own. A neighbor, played by Art Carney, in an unfortunately dolorous state, is also stricken by effects of the virulent chemical. The mother will be warned not to nurse her baby because the PBB has found its way into her own system.

Even on physical terms, Howard's performance is Olympic-caliber. He not only helps deliver calves, he struggles hopelessly to rouse a comatose cow, he gives mouth-to-mouth to a calf born dead, he uncovers a flock of farm rats killed by the chemical (and later dumps them, each in its own Baggie-coffin, on the conference table at the agriculture department), and he stands up to beefy, hardened bureaucrats.

As an actor and as a producer-director ("Skyward," earlier this season on NBC), Ron Howard seems determined to make a contribution to television, and with "Bitter Harvest," he and others in the case, director Roger Young and executive producer Charles Fries, have made one. This is a television movie with no phony happy ending and no artificial preservatives.

"Freedom" belongs to a faded genre -- sagas of Troubled Youth Finding Its Way -- but revives the form in very serious and occasionally commanding style. Young Libby, the girl played by Winningham, comes from an affluent but split household. Mom is a cold cod played by the always off-putting Jennifer Warren. The girl wants to move out on her own, on the grounds that she and her mother cannot get along.

Ah, but they really do love each other, it evolves -- after the youngster has toured parts of the land with a traveling carnival and had a mild affair with one of its rowdies (Peter Horton). She returns home on the day of her mother's second wedding. "We've punished each other long enough, haven't we, Libby?" Mom says and adds, later, teary-eyed, "I'm here for you. I'm only me. Take what you need."

Why do these mother-daughter fandangos degenerate into that kind of arch feelspeak? At least "Freedom" is better than the lugubrious "Strangers" on CBS last season. After watching it for a while, though, your eyebrows begin to ache. The weight of the world can get awfully arduous. Winningham, though, keeps the film watchable. She's more than just beautiful now, having evolved from the ingratiating pudge-o of "Amber Waves"; she's fascinating in her way, and not given to actor's tricks. Her responses always seem genuine, and she dignifies writer Barbara Turner's dialogue by breathing life even into the more unwieldy pronouncements.

Joseph Sargent, the director, breaks up the whimpering with such touches as a carnival-dismantling montage to "Orange Blossom Special." But the critical music of the film consists of a score written by Janis Ian and sung winningly by Winningham; the songs lift the film out of self-pitying doldrums more than once.Other merciful distractions include an appearance by venerable J. Pat O'Malley, who has aged very handsomely. As the owner of the carnival, he topples over in his lawn chair one day and dies, and the carnival crew salutes him by giving his casket one last ride on the Ferris wheel.

One last ride on the Ferris wheel is something to look forward to, all right.