Maximum acceptable toxicant concentration MATC

The chronic aquatic effects which relate silver speciation to adverse environmental effects were studied on rainbow trout eggs and fry. The maximum acceptable toxicant concentration (MATC) for silver nitrate, as total silver, was reported to be 90—170 ng/L (43). Using fathead minnow eggs and fry, the MATC, as total silver, for silver thiosulfate complexes was reported as 21—44 mg/L, and for silver sulfide as 11 mg/L, the maximum concentration tested (27). 

Table 2.5 Maximum Acceptable Toxicant Concentration (MATC) Values for Hexavalent and Trivalent Chromium to Aquatic Life Based on Life Cycle or Partial Life Cycle Exposures... 

The maximum acceptable toxicant concentration (MATC) values calculated for mirex and various freshwater species were ... 

Maximum acceptable toxicant concentration (MATC) valnes for hexavalent and trivalent chromium to aquatic life based on life cycle or partial life cycle exposures... 

The NOEC and the LOEC are the usual calculations reported from chronic toxicity tests. The NOEC is the highest concentration in which the measured effect is not statistically different from that of the control. The LOEC is the lowest concentration at which a statistically significant effect occurred. These concentrations are based on the most sensitive effect parameters, that is, hatchability, growth, and reproduction. The statistical procedure for these calculations combines the use of analysis of variance techniques and multiple comparison tests. In some cases, the maximum acceptable toxic concentration (MATC) is reported from chronic toxicity results. The MATC is a concentration [x) that is within the range of the NOEC and LOEC NOEC a < LOEC. The first-effect concentration can be expressed as the geometric mean of the two terms. 

Maximum acceptable toxicant concentration. MATC is the geometric mean of the LOEC and NOEC and is a commonly used expression of chronic aquatic toxicity Maximum exposure limit... 

Risk assessors also work with benchmarks that characterize the potential risk to the environment. The predicted no effect concentration (PNEC), in the terminology used in the European Union, is the concentration of a substance below which adverse effects will most likely not occur during long-term or short-term exposure. PNECs may be derived for aquatic organisms, terrestrial organisms, or the bacteria in a sewage treatment plant, for example, and are typically presented in units of mass per volume or mass. The US EPA has utilized similar parameters, the maximum acceptable toxicant concentration (MATC), and, as discussed further in Chapter 3, the concern concentration. 

Maximum acceptable toxicant concentration values (MATC) for toxaphene and aquatic organisms, based on exposure for the entire or most of the life cycle... 

Table 27.3 Maximum Acceptable Toxicant Concentration Values (MATC) for Toxaphene and Aquatic Organisms, Based on Exposure for the Entire or Most of the Life Cycle (Concentrations are in micrograms of toxaphene per liter [ppb].)... 

MATC = Maximum acceptable toxicant concentration. Lower value in each MATC pair indicates highest concentration tested producing no measurable effect on growth, survival, reproduction, and metabolism during chronic exposure higher value indicates lowest concentration tested producing a measurable effect. 

According to earlier reports 184), reproduction in invertebrate animals was affected by nickel concentrations significantly lower than those required to reduce egg production or survival of developmental stages of fish. This conclusion was based largely on results obtained for Daphnia 12) and the fathead minnow (756). As noted previously, Pickering gave an MATC between 380 and 730 fig Ni/liter for the fathead minnow exposed in hard water, and he estimated the maximum acceptable toxicant concentration in soft water to be 68-132 )ug/liter. By comparison, Biesinger and Christensen (72) observed 50 and 16% reproductive impairment in Daphnia at nickel concentrations of 95 and 30 tg/liter. 

All tests were flow-through unless otherwise specified. MATC, maximum acceptable toxicant concentration. 

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