(April 18, 2016, 11:22 AM EDT) -- TRENTON, N.J. — NL Industries Inc., which is one of the defendants in a lead contamination lawsuit brought by environmental groups, on April 8 filed a brief in New Jersey federal court, contending that the testimony of the plaintiffs’ expert witness should be precluded because his opinion is “not reliable” (Raritan Baykeeper Inc., et al. v. NL Industries Inc., et al., No. 09-4117, D. N.J.)....